CBD safety: what to know first
Summaries of FDA and NIH guidance. This is not medical advice. Talk with your health care provider before you start.
Possible side effects
FDA lists drowsiness, trouble sleeping, diarrhea, reduced appetite, stomach upset, irritability and agitation. NIH lists reduced alertness, mood changes, decreased appetite and diarrhea. FDA says these usually improve when use is reduced or stopped.
Liver injury
Both FDA and NIH say CBD may cause liver injury. FDA says it appeared in people not taking other drugs and worries it could go unnoticed without blood tests.
Medication interactions
FDA says CBD can raise or lower the effects of other medicines, and advises caution when combining it with herbs or supplements. Tell every provider and pharmacist about all medicines and supplements you take, including CBD.
Product quality
FDA says many tested products contained less CBD than labeled and is investigating contaminants including pesticides, heavy metals and THC. NIH says products may contain more or less CBD than their labels state.
If a product contains THC
VA's National Center for PTSD says today's cannabis is much more potent than in past decades, that extracts can contain up to 90% THC, and that edibles act more slowly, which can lead to taking too much.
What isn't known
FDA says it doesn't know the effects of long-term daily use, how much is too much, the combined effect of using several products, or the effects in children and during pregnancy and breastfeeding. Animal studies found male reproductive effects, and their relevance to people is unclear.
The law is changing
FDA says adding CBD to food or selling it as a dietary supplement is illegal under federal law. Hemp rules are also shifting: a federal limit of 0.4 mg total THC per container was delayed to December 11, 2026, and some states act sooner. Check your state's rules before you buy. Source for the delay: a law-firm summary, not a government site.
Sources: FDA: What You Need to Know (and What We're Working to Find Out) About Products Containing Cannabis or Cannabis-Derived Compounds, Including CBD; NIH NCCIH: Cannabis (Marijuana) and Cannabinoids: What You Need To Know (2019); VA National Center for PTSD: Cannabis Use and PTSD Among Veterans (updated Sept. 3, 2025); Foley Hoag: A temporary reprieve for hemp-THC products (Sept. 2026).