There are some people who should avoid ashwagandha. Dr. Lipman cautions, “Avoid if you’re pregnant, taking sedatives, or have severe gastric irritation or ulcers.” As noted before, those with elevated thyroid hormone levels should also use caution with ashwagandha.
To be classified as an adaptogen, an herb must meet three requirements: It must have a nonspecific effect on the body, it must promote and restore balance, and finally, it must be nontoxic and safe for long-term use. As such, ashwagandha is generally considered safe to consume. However, large doses have been reported to cause side effects such as upset stomach and diarrhea.