Mushroom Supplements: Functional Mushroom Research and Guides

Functional mushrooms are edible or traditionally used fungi such as lion's mane, reishi, cordyceps, chaga, turkey tail and shiitake, sold as powders, capsules, gummies and drinks for compounds such as beta-glucans. They are not psychoactive. In the United States they are sold as foods or dietary supplements, not as approved medicines.

The evidence is mixed and mostly early. Human trials of lion's mane, reishi and cordyceps are generally small and short, and results often have not been replicated. Product quality also varies: independent testing has found products with less of the claimed compounds than expected, or the wrong species. Our reviews report trial sizes and what remains unknown.

Published human trials report few side effects, mostly mild digestive complaints, but most enrolled fewer than 50 people for a few months. More serious signals come from case reports, including contact dermatitis and one case of drug-induced lung injury. The record looks unremarkable so far, but it is too thin to rule out uncommon harms.

Amanita muscaria is not a federally controlled substance, unlike psilocybin mushrooms, which are Schedule I. However, FDA said in December 2024 that Amanita muscaria and its constituents are not GRAS and are not authorised for use in conventional food, and it advises people not to eat foods containing them. Some states add their own restrictions.

Check that the label names the species in Latin, states whether it uses fruiting body or mycelium, and gives a measured figure for compounds such as beta-glucans. Ask for a batch certificate of analysis covering heavy metals and microbes. Treat any product claiming to treat or cure a disease as a red flag.