September 2019

Prescriptions vs Supplements: Fish Oil, CBD, Vitamin K

Several natural medicines are available in both prescription and supplement forms. Some patients might not understand the difference and assume they can use cheaper supplements in place of the prescription drug version. It’s important to dispel this myth since using supplement forms in place of prescription drugs can lead to improper care. Which ingredients should you keep your eye on?

Fish oil is one of the most popular dietary supplements. While patients take fish oil supplements for a variety of reasons, there are several prescription preparations available for specific conditions. Lovaza, Omtryg, and Epanova are all approved by the FDA to lower triglyceride levels in adults with severe hypertriglyceridemia. While taking fish oil supplements might also benefit these patients, up to 12 capsules of fish oil supplements daily might be needed to produce the same effects as the drugs.

Similarly, Vascepa, a prescription form of eicosapentaenoic acid (EPA), is also FDA approved for lowering triglyceride levels. But there’s no evidence that taking EPA supplements will have the same effect. Amarin, the makers of Vascepa, recently filed a citizen petition stating that it should not be legal for synthetic forms of EPA to be sold in dietary supplements, noting that the line between dietary supplements and prescription drugs is continuing to blur.

CBD is another hot and controversial ingredient in the supplement world. Although a prescription CBD product (Epidiolex) is FDA-approved for treating specific seizure disorders in children, it’s unclear if CBD supplements will offer this or other benefits. Furthermore, it’s currently illegal under federal law for CBD to be marketed as a food or dietary supplement. CBD products other than Epidiolex don't have to be tested for safety, efficacy, or quality. Many of these products will not contain the amount of CBD claimed on the label and could include contaminants, such as THC.

Several other ingredients, including vitamin K, are also available in both supplement and prescription forms. When prescribing any of these ingredients in drug form, make sure to discuss the differences with patients. Supplements are not regulated or standardized in the same way as prescription products. This means that you know what you're getting when you take a prescription medication - you don't have this same level of assurance with a supplement. And the dose and concentration of a supplement may not even come close to the prescription version of the same ingredient. For more details, review the effectiveness sections of these monographs where we clearly distinguish when research is only supportive of prescription drug forms, not supplements.

The information in this brief report is intended for informational purposes only, and is meant to help users better understand health concerns. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions. Copyright © 2024 NatMed. Commercial distribution or reproduction prohibited. NatMed is the leading provider of high-quality, evidence-based, clinically-relevant information on natural medicine, dietary supplements, herbs, vitamins, minerals, functional foods, diets, complementary practices, CAM modalities, exercises and medical conditions. Monograph sections include interactions with herbs, drugs, foods and labs, contraindications, depletions, dosing, toxicology, adverse effects, pregnancy and lactation data, synonyms, safety and effectiveness.