Green Mate by Jarrow Formulas

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Arrhythmia. Although there has been interest in using oral yerba mate for arrhythmia, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Athletic performance. It is unclear if oral yerba mate is beneficial for improving athletic performance. Details: A small clinical study shows that taking yerba mate 5 grams orally daily for 5 days prior to a cycling exercise shortens time to completion by 2% and modestly improves absolute power when compared with placebo in trained athletes (96471).
• Cognitive function. It is unclear if oral yerba mate is beneficial for improving cognitive function. Details: Preliminary clinical research shows that drinking a single beverage containing one tablespoon of yerba mate does not improve vigilance, working memory, reaction time, or accuracy when compared with decaffeinated coffee controls in healthy females ages 17-35 years (86712).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral yerba mate for CFS, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Depression. Although there has been interest in using oral yerba mate for depression, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Diabetes. It is unclear if oral yerba mate is beneficial in patients with diabetes. Details: Preliminary clinical research shows that drinking yerba mate tea, prepared by steeping 6.6 grams of leaves for 10 minutes in 330 mL of boiling water, three times daily for 60 days decreases fasting blood glucose by up to 17% and glycated hemoglobin (HbA1c) by 0.85% when compared with baseline in patients with type 2 diabetes (86693). The validity of these findings is limited by the lack of a comparator group.
• Dyslipidemia. It is unclear if oral yerba mate is beneficial in patients with dyslipidemia. Details: A meta-analysis of 7 small, mostly low to moderate quality clinical studies in adults shows that taking yerba mate orally does not reduce levels of total, low-density lipoprotein (LDL) cholesterol, or triglycerides or improve high-density lipoprotein (HDL) cholesterol when compared with placebo or dietary intervention (111738). However, the validity of this study is limited by the heterogeneity of the included studies which enrolled patients with varying conditions and used various forms and doses of yerba mate. Other clinical research in patients with dyslipidemia or hypercholesterolemia shows that drinking 330 mL of tea containing yerba mate 20 mg/mL three times daily for 40 days reduces LDL cholesterol levels by 9% and increases HDL cholesterol levels by 4% when compared with baseline. The effects of yerba mate were similar between patients on low- to moderate-intensity statin therapy and those not taking statins. Drinking yerba mate tea did not affect triglyceride levels (86657).
• Fatigue. Although there has been interest in using oral yerba mate for fatigue, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Headache. Although there has been interest in using oral yerba mate for headache, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Heart failure. Although there has been interest in using oral yerba mate for heart failure, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Impaired glucose tolerance (Prediabetes). It is unclear if oral yerba mate is beneficial in patients with prediabetes. Details: Clinical research shows that drinking yerba mate tea, prepared by steeping 6.6 grams of leaves for 10 minutes in 330 mL of boiling water, three times daily for 60 days reduces glycated hemoglobin (HbA1C) by 0.4%, but not fasting blood glucose levels, when compared with baseline in patients with prediabetes (86693). The validity of these findings is limited by the lack of a comparator group.
• Joint pain. Although there has been interest in using oral yerba mate for joint pain, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Kidney stones (nephrolithiasis). Although there has been interest in using oral yerba mate for nephrolithiasis, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Mental alertness. Although there has been interest in using oral yerba mate for mental alertness, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Muscle strength. It is unclear if oral yerba mate improves muscle strength. Details: A small clinical crossover study in males shows that consuming a beverage containing 3 grams of yerba mate (Matte Leão, Valinhos Brazil) 1-hour prior to bench press and leg press strength training does not improve muscle strength when compared with placebo (111739).
• Obesity. It is unclear if oral yerba mate is beneficial in patients with obesity. Details: Although some observational research in healthy patients has found that high consumption of yerba mate is associated with increased weight (99322), most preliminary clinical research in adults with obesity shows that consuming yerba mate might improve some parameters (11866,92152,96470). Two, small, randomized controlled trials in obese Korean adults shows that taking yerba mate 3 grams daily, in 2-3 divided doses, for 6-12 weeks does not reduce weight, body mass index, or lipid levels when compared with placebo. Taking yerba mate modestly improved other measures, such as fat mass, waist-hip ratio, and waist circumference when compared with baseline, but these results were not consistent between trials and the studies may have been inadequately powered to detect a difference between groups (92152,96470).
• Osteoporosis. It is unclear if oral yerba mate is beneficial in patients with osteoporosis. Details: In an observational study, consumption of at least 1 liter of yerba mate tea daily for a minimum of 4 years was associated with higher lumbar spine and femoral neck bone densities, with increases of 9.7% and 6.2%, respectively (17184). In contrast, a small case-control study found no association between yerba mate consumption and markers of bone resorption and formation in postmenopausal adults, regardless of the duration of yerba mate consumption (96468). Neither study identified an association between fracture rates; however, these studies may have been inadequately powered to detect a difference between groups (17184,96468).
• Parkinson Disease. It is unclear if oral yerba mate is beneficial in preventing Parkinson disease. Details: A small observational study has found that high consumption of yerba mate tea is associated with 59% to 63% lower odds of being diagnosed with Parkinson disease when compared with no consumption of yerba mate (106860).
• Urinary tract infections (UTIs). Although there has been interest in using oral yerba mate for UTIs, there is insufficient reliable information about the clinical effects of yerba mate for this purpose. More evidence is needed to rate yerba mate for these uses.

(Read more about YERBA MATE)

POSSIBLY SAFE ...when used orally and appropriately, short-term (11866). Yerba mate has been safely used in doses of 3 grams daily for up to 12 weeks (92152,96469,96470).

POSSIBLY UNSAFE ...when yerba mate is used orally in large amounts or for prolonged periods of time. Drinking approximately 1-2 liters, or 4-8 cups, of yerba mate daily is associated with an increased risk of cancer, including esophageal, stomach, kidney, bladder, cervical, prostate, lung, renal cell, and possibly laryngeal and mouth cancer (1528,1529,1530,1531,11863,11864,92150). Yerba mate also contains caffeine. Acute use of high doses of caffeine (more than 400 mg per day), which is found in more than 8-10 cups of yerba mate, has been associated with significant adverse effects such as tachyarrhythmia and sleep disturbances (11832). Drinking yerba mate in amounts greater than 12-15 cups daily (about 600 mg caffeine) short-term or long-term can also cause caffeinism with symptoms of anxiety possibly progressing to delirium and agitation. Chronic use of caffeine, especially in large amounts, can sometimes produce tolerance, habituation, and psychological dependence (3719). Abrupt discontinuance of caffeine can cause physical withdrawal symptoms (11733). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as yerba mate, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

CHILDREN: POSSIBLY UNSAFE
when used orally. Yerba mate is associated with an increased risk of cancer, including esophageal, kidney, bladder, cervical, prostate, lung, and possibly mouth and laryngeal cancer (1528,1529,1530,1531,11863,11864,92150).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Yerba mate is associated with an increased risk of cancer, including esophageal, kidney, bladder, cervical, prostate, lung, renal cell, and possibly mouth and laryngeal cancer (1528,1529,1530,1531,11863,11864,92150,86595,86614,86700,86701). However, teratogenic studies have not been performed. Yerba mate also contains caffeine. Caffeine crosses the placenta, producing fetal blood concentrations similar to parental levels. According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, most healthy pregnant patients can safely consume caffeine in doses up to 300 mg daily without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations (11733,98806). It is generally recommended to avoid consuming more than 300 mg of caffeine daily, or around 6-7 cups of yerba mate daily, when pregnant (2708). High doses of caffeine throughout pregnancy have resulted in symptoms of caffeine withdrawal in newborn infants (9891,86618). Caffeine in doses of greater than 300 mg daily has also been associated with spontaneous abortion, premature delivery, and low birth weight (2709,2711), although one retrospective study found that consuming yerba mate tea during pregnancy was not associated with preterm or small for gestational age births (13113). However, this study did not consider the amount of yerba mate or caffeine consumed, only the frequency of consumption. Some research has found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years (109846).

LACTATION: POSSIBLY UNSAFE
when used orally. Yerba mate is associated with an increased risk of cancer, including esophageal, kidney, bladder, cervical, prostate, lung, renal cell, and possibly mouth and laryngeal cancer (1528,1529,1530,1531,11863,11864,92150). Whether carcinogenic constituents of yerba mate are transferred via breast milk is unknown. Yerba mate contains caffeine. Consumption of yerba mate might cause irritability and increased bowel activity in nursing infants (6026).

(Read more about YERBA MATE)

ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Yerba mate contains caffeine. Some evidence shows that caffeine is a competitive inhibitor of adenosine and can reduce the vasodilatory effects of adenosine in humans (38172). However, other research shows that caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine (11771). Still, some researchers recommend that methylxanthines, such as caffeine, as well as methylxanthine-containing products, should be stopped 24 hours prior to pharmacological stress tests (11770). However, methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

ALCOHOL (Ethanol) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of alcohol and yerba mate might increase levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Alcohol reduces caffeine metabolism. Concomitant use of alcohol can increase caffeine serum concentrations and the risk of caffeine adverse effects (6370,24693).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Yerba mate contains caffeine. Caffeine is reported to have antiplatelet activity. Theoretically, it might increase the risk of bleeding when used concomitantly with these agents (8028,8029); however, this interaction has not been reported in humans.

ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, taking yerba mate with antidiabetes drugs might interfere with blood glucose control.  Details Yerba mate contains caffeine. Reports claim that caffeine might increase or decrease blood sugar (6024,8646).

BENZODIAZEPINES Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the efficacy of benzodiazepines.  Details Yerba mate contains caffeine. Caffeine can antagonize the anxiolytic effects of benzodiazepines (24951,24952,24953,24954,24955).

BETA-ADRENERGIC AGONISTS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the cardiac inotropic effects of beta-agonists, especially if taken in large amounts.  Details Yerba mate contains caffeine. Caffeine can increase cardiac inotropic effects of beta-agonists (15).

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might reduce the effects of carbamazepine and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can lower the anticonvulsant effects of carbamazepine and can induce seizures when taken in doses above 400 mg/kg (23561). Human research has shown that taking caffeine 300 mg in three divided doses along with carbamazepine 200 mg reduces the bioavailability of carbamazepine by 32% and prolongs the plasma half-life of carbamazepine two-fold in healthy individuals (23562).

CIMETIDINE (Tagamet) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Likely •  Level of Evidence = B Theoretically, cimetidine might increase the levels and adverse effects of the caffeine contained in yerba mate.  Details Yerba mate contains caffeine. Cimetidine decreases caffeine clearance by 31% to 42% (11736,24700).

CLOZAPINE (Clozaril) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Yerba mate contains caffeine. Caffeine might increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg per day inhibit clozapine metabolism (5051). Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Although researchers speculate that caffeine might inhibit CYP1A2, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to an interaction between clozapine and caffeine (13741).

CONTRACEPTIVE DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, contraceptive drugs might increase the levels and adverse effects of the caffeine contained in yerba mate.  Details Yerba mate contains caffeine. Contraceptive drugs decrease the rate of caffeine clearance by 40% to 65% (2714,11737).

CYTOCHROME P450 1A2 (CYP1A2) INHIBITORS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of CYP1A2 inhibitors and yerba mate might increase levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Caffeine is metabolized by CYP1A2. Theoretically, drugs that inhibit CYP1A2 may decrease the rate of caffeine clearance and increase caffeine levels (5051,11741).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, yerba mate might increase the levels and clinical effects of CYP3A4 substrates.  Details In vitro research shows that yerba mate extract inhibits CYP3A4 enzymes (105811). Theoretically, taking yerba mate may increase levels and adverse effects of CYP3A4 substrates.

DIPYRIDAMOLE (Persantine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, the caffeine in yerba mate might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Yerba mate contains caffeine. Caffeine inhibits dipyridamole-induced vasodilation (11770,11772). Still, some researchers recommend that methylxanthines, such as caffeine, as well as methylxanthine-containing products, should be stopped 24 hours prior to pharmacological stress (11770). Methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

DISULFIRAM (Antabuse) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, disulfiram might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Disulfiram decreases the rate of caffeine clearance (15,11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the risk of hypokalemia when used concomitantly with other diuretics.  Details Yerba mate contains caffeine. Caffeine, especially in excessive amounts, can reduce potassium levels due to stimulation of the sodium-potassium pump (23579,37905,37953,38003,38034). Diuretics can also cause lower potassium levels.

EPHEDRINE Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the risk for stimulant adverse effects when used concomitantly with ephedrine.  Details Use of ephedrine with caffeine can increase the risk of stimulatory adverse effects. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death (1275,6486,10307).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, estrogens might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Estrogen inhibits caffeine metabolism (2714).

ETHOSUXIMIDE (Zarontin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of ethosuximide and increase the risk for convulsion.  Details Yerba mate contains caffeine. Animal research shows that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide (23560). However, this effect has not been reported in humans.

FELBAMATE (Felbatol) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of felbamate and increase the risk for convulsion.  Details Yerba mate contains caffeine. Animal research shows that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate (23563). However, this effect has not been reported in humans.

FLUCONAZOLE (Diflucan) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, fluconazole might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Fluconazole decreases caffeine clearance by approximately 25% (11022,24978).

FLUTAMIDE (Eulexin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of flutamide.  Details Yerba mate contains caffeine. In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide (23553). However, this effect has not been reported in humans.

FLUVOXAMINE (Luvox) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, fluvoxamine might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Fluvoxamine reduces caffeine metabolism (6370,38287).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt withdrawal of the caffeine in yerba mate might increase serum lithium levels.  Details Yerba mate contains caffeine, which has diuretic activity. When abruptly discontinued, it might alter the clearance of lithium (609). There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal (609,610).

METFORMIN (Glucophage) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, metformin might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Animal research suggests that metformin can reduce caffeine metabolism (23571). However, this effect has not been reported in humans.

METHOXSALEN (Oxsoralen) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, methoxsalen might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Methoxsalen reduces caffeine metabolism (23572).

MEXILETINE (Mexitil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, mexiletine might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Mexiletine decreases caffeine elimination by approximately 50% (1260,11741,24981).

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, use of yerba mate with midazolam might increase midazolam metabolite levels and adverse effects.  Details In vitro research shows that yerba mate extract containing 6.75% chlorogenic acid significantly inhibits the metabolism of midazolam via inhibition of cytochrome P450 3A4 (CYP3A4)(105811).

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase risk of a hypertensive crisis when used concomitantly with MAOIs.  Details Yerba mate contains caffeine. Caffeine has been shown to inhibit monoamine oxidase (MAO) A and B in laboratory studies (37724,37877,37912,38108). Concomitant intake of large amounts of caffeine with MAOIs might precipitate a hypertensive crisis (15). In a case report, a patient that consumed 10-12 cups of caffeinated coffee and took the MAOI tranylcypromine presented with severe hypertension (91086). Hypertension was resolved after the patient switched to drinking decaffeinated coffee.

NICOTINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase risk of hypertension when used concomitantly with nicotine.  Details Yerba mate contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly (2719,36549).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might decrease the effects of pentobarbital.  Details The caffeine in yerba mate might negate the hypnotic effects of pentobarbital (13742).

PHENOBARBITAL (Luminal) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of phenobarbital and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital (23558,23561). However, the exact mechanism of this interaction is unclear.

PHENYLPROPANOLAMINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, phenylpropanolamine might increase the risk of hypertension as well as the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure (11738). Phenylpropanolamine also seems to increase caffeine serum levels (13743).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might reduce the effects of phenytoin and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenytoin (23561). The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.

PIOGLITAZONE (Actos) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and clinical effects of pioglitazone.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can modestly increase the maximum concentration, area under the curve, and half-life of pioglitazone, and also reduce its clearance. This increased the antidiabetic effects of pioglitazone (108812). However, the exact mechanism of this interaction is unclear.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, quinolone antibiotics might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting cytochrome P450 1A2 (CYP1A2) enzyme (606,607,608,23554,23555,23556).

RILUZOLE (Rilutek) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of riluzole and yerba mate might increase levels and adverse effects of both riluzole and the caffeine in yerba mate.  Details Yerba mate contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce the metabolism of one or both agents (11739).

STIMULANT DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Theoretically, concomitant use of stimulant drugs and yerba mate might increase stimulant adverse effects.  Details Yerba mate contains caffeine. Due to the CNS stimulant effects of the caffeine, concomitant use can increase the risk of adverse effects (11832).

TERBINAFINE (Lamisil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, terbinafine might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Terbinafine decreases the rate of caffeine clearance by 19% (11740).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of theophylline.  Details Yerba mate contains caffeine. Caffeine decreases theophylline clearance by 23% to 29% (11741).

TIAGABINE (Gabitril) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of tiagabine.  Details Yerba mate contains caffeine. Animal research suggests that chronic caffeine administration can increase the serum concentrations of tiagabine. However, concomitant use does not seem to reduce the antiepileptic effects of tiagabine (23561).

TICLOPIDINE (Ticlid) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, ticlopidine might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. In vitro research shows that ticlopidine can inhibit caffeine metabolism (23557). However, this effect has not been reported in humans.

VALPROATE Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of valproate and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of valproate (23558,23561). However, the exact mechanism of this interaction is unclear.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, verapamil might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Verapamil increases plasma caffeine concentrations by 25% (11741).

(Read more about YERBA MATE)

General ...When used orally in high doses or long-term, yerba mate may be unsafe.
Most Common Adverse Effects:
Orally: Many of the adverse effects of yerba mate can be attributed to its caffeine content, such as diuresis, gastric irritation, insomnia, nausea, nervousness, restlessness, tachycardia, tachypnea, and tremors.
Serious Adverse Effects (Rare):
Orally: Cancer, hyperglycemia, ketosis, metabolic acidosis, sinus tachycardia. These adverse effects are more common with high doses or long-term use.

Cardiovascular ...Orally, yerba mate may cause cardiovascular-related adverse effects due to its caffeine content. High doses of mate providing 250 mg of caffeine can increase blood pressure. However, this doesn't seem to occur in people who habitually consume caffeine products (2722). Also, epidemiological research suggests that there is no association of caffeine consumption with incidence of hypertension (13739).
Due to its caffeine content, yerba mate may cause other adverse cardiovascular effects when used orally. These effects include tachycardia, quickened respiration, chest pain, premature heartbeat, arrhythmia, and hypertension (11832,11838,13735). Large doses of caffeine can also cause massive catecholamine release and subsequent sinus tachycardia (13734). There is also one report of venous occlusive disease associated with excessive, long-term mate consumption (5614).
Epidemiological research has found that regular caffeine intake of up to 400 mg per day, or approximately 8-10 cups of yerba mate, is not associated with an increased incidence of atrial fibrillation (38018,38076,91028,91034,97451,97453), atherosclerosis (38033), cardiac ectopy (91127), stroke (37804), ventricular arrhythmia (95948,97453), and cardiovascular disease in general (37805,98806).
Combining caffeine beverages such as yerba mate with ephedra may theoretically increase the risk of adverse cardiovascular events. There is one report of ischemic stroke in an athlete who consumed ephedra 40-60 mg, creatine monohydrate 6 grams, caffeine 400-600 mg, and a variety of other supplements daily for six weeks (1275).

Endocrine ...Yerba mate contains caffeine. Orally, large doses of caffeine can cause massive catecholamine release and subsequent metabolic acidosis, hyperglycemia, and ketosis (13734). Some evidence shows caffeine is associated with fibrocystic breast disease, breast cancer, and endometriosis in females. However, this is controversial since findings are conflicting (8043). Restricting caffeine in females with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain (8996). A population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages and the incidence of invasive breast cancer in models adjusted for demographic, lifestyle, and reproductive factors (108806). Also, a dose-response analysis of 2 low-quality observational studies has found that high consumption of caffeine is not associated with an increased risk of breast cancer (108807).

Gastrointestinal ...Orally, drinking yerba mate infusions has been associated with nausea and irritation of the stomach or oral mucosa in a small number of patients in one clinical study (86657). Yerba mate contains caffeine. Orally, caffeine can cause gastric irritation, nausea, and vomiting (11832,11838,13735). Caffeine-containing beverages can stimulate gastric secretion in humans, which may potentiate ulcer symptoms (36404). Some believe that long-term use of caffeine can cause withdrawal symptoms following discontinuation of use. However, the existence of caffeine withdrawal is controversial. Some researchers think that if it exists, it appears to be of little clinical significance (2723,11839). Gastrointestinal withdrawal symptoms such as nausea and vomiting have been described. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects. Clinically significant gastrointestinal symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Hematologic ...Yerba mate contains caffeine. Orally, caffeine can cause hypokalemia (11832,11838,13735).

Immunologic ...Yerba mate contains caffeine. Orally, caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare (11315).

Musculoskeletal ...Yerba mate contains caffeine. Some epidemiological research suggests that caffeine may be associated with an increased risk of osteoporosis, but conflicting evidence exists. Caffeine can increase urinary excretion of calcium (2669,10202,11317). Females identified with a genetic variant of the vitamin D receptor appear to be at an increased risk for the detrimental effect of caffeine on bone mass (2669). However, moderate caffeine intake of less than 400 mg per day, or approximately 8-10 cups of yerba mate, does not seem to significantly increase osteoporosis risk in most postmenopausal adults with normal calcium intake (2669,6025,10202,11317,98806).

Some researchers believe that stopping regular use of caffeine may cause withdrawal symptoms such as muscle tension and muscle pains. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects (2723,11839). However, there is a case of withdrawal in a premature neonate following chronic parental drinking of yerba mate (86618). Symptoms included hypertonia in the limbs and brisk tendon reflexes. The authors indicated that high concentrations of caffeine and theobromine were found in the placenta, cord serum, neonatal urine, parental and neonatal hair, meconium, and breast milk. Although symptoms progressively disappeared at 84 hours of age, irritability was still occasionally present at discharge (24 days of age).

Neurologic/CNS ...Orally, drinking yerba mate infusions has been associated with insomnia in a small number of patients in one clinical study (86657). Yerba mate contains caffeine. Orally, caffeine can cause insomnia, nervousness, headache, anxiety, agitation, jitteriness, restlessness, ringing in the ears, tremors, delirium, and convulsions (11832,11838,13735). Caffeine may also exacerbate sleep disturbances in patients with acquired immunodeficiency syndrome (AIDS) (10204).
There is some concern that stopping regular use of caffeine may cause withdrawal symptoms such as headache, tiredness and fatigue, decreased energy, alertness, and attentiveness, drowsiness, decreased contentedness, depressed mood, difficulty concentrating, irritability, and lack of clear-headedness are typical of caffeine withdrawal (13738). Other symptoms such as delirium, nervousness, restlessness, and anxiety have been described. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects (2723,11839). However, there is a case of withdrawal in a premature neonate following chronic parental drinking of yerba mate (86618). Symptoms included jitteriness and irritability and a high-pitched cry. The authors indicated that high concentrations of caffeine and theobromine were found in the placenta, cord serum, neonatal urine, parental and neonatal hair, meconium, and breast milk. Although symptoms progressively disappeared at 84 hours of age, irritability was still occasionally present at discharge (24 days of age).

Oncologic ...Orally, the prolonged use of yerba mate or use of yerba mate in high doses (typically more than 1-2 liters daily) is associated with an increased risk of cancer, including mouth, esophageal, laryngeal, kidney, bladder, cervical, prostate, and lung cancer (1528,1529,1530,1531,11863,11864,92150,86595,86614,86700,86701). The effect seems to be cumulative and dose dependent. The risk of cancer with yerba mate use seems to increase if it is taken as a warm beverage. In 1991, the International Agency for Research on Cancer (IARC), reported that hot yerba mate drinking is a 2A agent, meaning it is probably carcinogenic for humans (92150). A statement published in 2016 stated there is no conclusive evidence for carcinogenicity when yerba mate is consumed at temperatures that are "not very hot" (95015). Drinking very hot beverages is believed to be a probable cause of esophageal cancer in humans (95015). Concomitant tobacco and alcohol use can increase risk 7-fold (11863).

Pulmonary/Respiratory ...Yerba mate contains caffeine. Orally, caffeine may cause tachypnea-induced respiratory alkalosis (11832,11838,13735). Some researchers think that stopping regular use of caffeine may cause withdrawal symptoms such as runny nose. However, this symptom may be from nonpharmacological factors related to knowledge and expectation of effects (2723,11839).

Renal ...Yerba mate contains caffeine. Orally, caffeine may cause diuresis (11832,11838,13735).

(Read more about YERBA MATE)