Safety and Effectiveness Rating

SAFETY

For each natural medicine monograph in the Database you get an evidence-based Safety Rating. These are PRACTICAL ratings that are STANDARDIZED throughout Natural Medicines.

You will see that different routes of administration of a product often get different safety ratings. For example, camphor is rated "LIKELY SAFE" when used topically, but it is rated "UNSAFE" when used orally.

Questions often come up about using products during pregnancy or lactation, or in children. If there are safety considerations that apply specifically to children, a special mention in the safety field will address the concern. Every listing also includes a Safety Rating for pregnancy and lactation.

Our team meticulously analyzes the medical literature to assign the Safety Ratings. Each rating is assigned according to specific criteria:

LIKELY SAFE:
This product has a very high level of reliable clinical evidence showing its safe use when used appropriately. Products rated Likely Safe are generally considered appropriate to recommend.

To achieve this Safety Rating a product is supported by all of the following:

  • Safety data is available from multiple (2+) randomized clinical trials or meta-analysis or large-scale post-marketing surveillance including several hundred patients (level of evidence = A). Or the product has undergone a safety review consistent with or equivalent to passing a review by the Food and Drug Administration (FDA), Health Canada, or similarly rigorous approval process.
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Studies adequately measure and report safety and adverse outcomes data and consistently show no significant serious adverse effects without valid evidence to the contrary.

POSSIBLY SAFE:
This product has some clinical evidence showing its safe use when used appropriately; however, the evidence is limited by quantity, quality, or contradictory findings. Products rated "Possibly Safe" appear to be safe, but do not have enough high-quality evidence to recommend for most people.

To achieve this Safety Rating a product is supported by all of the following:

  • Safety data is available from one or more randomized clinical trials, meta-analysis (level of evidence = A or B), case series, two or more population based or epidemiological studies (level of evidence = B), or limited post-marketing surveillance data.
  • Studies have a low to moderate risk of bias and moderate to high level of validity by meeting or partially meeting assessment criteria (quality rating A or B).
  • Studies adequately measure and report safety and adverse outcomes data and show no significant serious adverse effects without substantial evidence to the contrary. Some contrary evidence may exist; however, valid evidence supporting safety outweighs contrary evidence.

POSSIBLY UNSAFE:
This product has some clinical evidence showing safety concerns or significant adverse outcomes; however, the evidence is limited by quantity, quality, or contradictory findings. People should be advised NOT to take products with a "Possibly Unsafe" rating.

To achieve this Safety Rating a product is supported by all of the following:

  • Safety data is available from one or more randomized clinical trials, meta-analysis (level of evidence = A or B), two or more population based or epidemiological studies (level of evidence = B), or limited post-marketing surveillance data. Or multiple, reliable case reports show a potential causal relationship between a product and serious adverse outcome.
  • Studies have a low to moderate risk of bias and moderate to high level of validity by meeting or partially meeting assessment criteria (quality rating A or B).
  • Studies adequately measure and report safety and adverse outcomes data and show significant serious adverse effects without substantial evidence to the contrary. Some contrary evidence may exist; however, valid evidence supporting potential safety concerns outweigh contrary evidence.

LIKELY UNSAFE:
This product has a very high level of reliable clinical evidence showing safety concerns or significant adverse outcomes. People should be discouraged from taking products with a "Likely Unsafe" rating.

To achieve this Safety Rating a product is supported by all of the following:

  • Safety data is available from multiple (2+) randomized clinical trials, meta-analysis, or large-scale post-marketing surveillance including several hundred patients (level of evidence = A).
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Studies adequately measure and report safety and adverse outcomes data and consistently show significant serious adverse effects without valid evidence to the contrary.

UNSAFE:
This product has a very high level of reliable clinical evidence showing safety concerns or significant adverse outcomes. People should be discouraged from taking products with an Unsafe rating.

To achieve this Safety Rating a product is supported by all of the following:

  • Safety data is available from multiple (2+) randomized clinical trials, meta-analysis, or large-scale post-marketing surveillance including several hundred to several thousand patients (level of evidence = A).
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Studies adequately measure and report safety and adverse outcomes data and consistently show significant serious adverse effects without valid evidence to the contrary.

INSUFFICIENT EVIDENCE:
There is not enough reliable scientific evidence to provide a Safety Rating.

EFFECTIVENESS

Effectiveness Ratings are assigned for specific indications. A product might be rated “Possibly Effective” for one condition, but be rated “Likely Ineffective” for another condition, depending on the evidence.

The evidence-based criteria for Effectiveness Ratings is as follows:

EFFECTIVE:
This product has a very high level of reliable clinical evidence supporting its use for a specific indication. Products rated Effective are generally considered appropriate to recommend.

To achieve this Effectiveness Rating a product is supported by all of the following:

  • Evidence consistent with or equivalent to passing a review by the Food and Drug Administration (FDA), Health Canada, or similarly rigorous approval process.
  • Evidence from multiple (2+) randomized clinical trials or meta-analysis including several hundred to several thousand patients (level of evidence = A).
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Evidence consistently shows POSITIVE outcomes for a given indication without valid evidence to the contrary.

LIKELY EFFECTIVE:
This product has a very high level of reliable clinical evidence supporting its use for a specific indication. Products rated "Likely Effective" are generally considered appropriate to recommend.

To achieve this Effectiveness Rating a product is supported by all of the following:

  • Evidence from multiple (2+) randomized clinical trials or meta-analysis including several hundred patients (level of evidence = A).
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Evidence consistently shows POSITIVE outcomes for a given indication without significant valid evidence to the contrary.

POSSIBLY EFFECTIVE:
This product has some clinical evidence supporting its use for a specific indication; however, the evidence is limited by quantity, quality, or contradictory findings. Products rated "Possibly Effective" might be beneficial, but do not have enough high-quality evidence to recommend for most people.

To achieve this Effectiveness Rating a product is supported by all of the following:

  • One or more randomized clinical trials or meta-analysis (level of evidence = A or B) or two or more population based or epidemiological studies (level of evidence = B).
  • Studies have a low to moderate risk of bias and moderate to high level of validity by meeting or partially meeting assessment criteria (quality rating A or B).
  • Evidence shows POSITIVE outcomes for a given indication without substantial valid evidence to the contrary. Some contrary evidence may exist; however, valid positive evidence outweighs contrary evidence.

POSSIBLY INEFFECTIVE:
This product has some clinical evidence showing ineffectiveness for a specific indication; however, the evidence is limited by quantity, quality, or contradictory findings. People should be advised NOT to take products with a "Possibly Ineffective" rating.

To achieve this Effectiveness Rating a product is supported by all of the following:

  • One or more randomized clinical trials or meta-analysis (level of evidence = A or B) or two or more population based or epidemiological studies (level of evidence = B).
  • Studies have a low to moderate risk of bias and moderate to high level of validity by meeting or partially meeting assessment criteria (quality rating A or B).
  • Evidence shows NEGATIVE outcomes for a given indication without substantial valid evidence to the contrary. Some contrary evidence may exist; however, valid positive evidence outweighs contrary evidence.

LIKELY INEFFECTIVE:
This product has a very high level of reliable clinical evidence showing ineffectiveness for its use for a specific indication. People should be discouraged from taking products with a "Likely Ineffective" rating.

To achieve this Effectiveness Rating a product is supported by all of the following:

  • Evidence from multiple (2+) randomized clinical trials or meta-analysis including several hundred patients (level of evidence = A).
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Evidence consistently shows NEGATIVE outcomes for a given indication without significant valid evidence to the contrary.

INEFFECTIVE:
This product has a very high level of reliable clinical evidence showing ineffectiveness for its use for a specific indication. People should be discouraged from taking products with an "Ineffective" rating.

To achieve this Effectiveness Rating a product is supported by all of the following:

  • Evidence from multiple (2+) randomized clinical trials or meta-analysis including several hundred to several thousand patients (level of evidence = A).
  • Studies have a low risk of bias and high level of validity by meeting stringent assessment criteria (quality rating = A).
  • Evidence consistently shows NEGATIVE outcomes for a given indication without valid evidence to the contrary.

INSUFFICIENT EVIDENCE:
There is not enough reliable scientific evidence to provide an Effectiveness Rating.

 

It is important to keep in mind that different studies often use different product extracts or formulations. Results from studies using specific product formulations can only be applied to that one formulation of the product and cannot be extrapolated to other extracts or product formulations. In some cases, different study results are found when different product formulas are used.