Contraindication
A contraindication is a situation in which a product should not be used because the risk clearly outweighs any possible benefit, such as use by people of a particular age, sex or condition, or alongside another therapy.
What it means in practice
US prescription labeling rules give the term its formal shape. The Contraindications section of a drug label must describe any situations in which the drug should not be used because the risk of use clearly outweighs any possible therapeutic benefit [2]. Those situations include people who, because of their particular age, sex, concomitant therapy, disease state or other condition, have a substantial risk of being harmed [2]. The rule asks for known hazards, not theoretical possibilities, and if no contraindications are known the section must say "None" [2].
The same rule keeps contraindications apart from warnings and precautions, a summary that includes information affecting decisions about whether to prescribe a drug and the patient monitoring that is critical to safe use [2]. In plain terms, a contraindication is a stop sign and a warning is a caution.
These labeling requirements apply only to prescription drug products [2]. For herbs and dietary supplements, a 2012 systematic review collected 152 documented contraindications; the most frequent involved gastrointestinal (16.4%), neurological (14.5%) and renal or genitourinary (12.5%) conditions [1]. Flaxseed, echinacea and yohimbe had the largest number of documented contraindications [1].
Why it matters when reading nootropics research
Check who issued a contraindication before weighing it. NootropicsWork counts a regulator's contraindication toward a compound's safety flag when it is specific to that compound. A generic label caution for a whole category of products, such as advice to consult a practitioner during pregnancy, does not count.
A contraindication describes a defined group, not everyone: one listed for people taking a particular medicine says nothing about people who are not. The labeling rule's test, known hazards rather than theoretical possibilities [2], is a useful one to apply to any contraindication a reader meets in a herb database or on a product listing.
References
- Tsai HH, Lin HW, Simon Pickard A, et al. Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review. Int J Clin Pract. 2012.
- U.S. Office of the Federal Register (eCFR). 21 CFR 201.57 Specific requirements on content and format of labeling for human prescription drug and biological products. eCFR up to date as of 2026-11-09.