Lion's Mane Side Effects and Allergy Reports
Side effects and allergy reports for lion's mane as read in trials and case reports: mild stomach upset, rare skin, breathing and anaphylaxis reports, and when to ask for help.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Get urgent help (911 in the US) for trouble breathing, swelling of the face or throat, or fainting after eating a mushroom or taking a mushroom product. See severe allergic reactions to natural products. Do not stop or change a prescribed medicine yourself; ask the prescriber or pharmacist.
In the human trials we read, lion's mane (Hericium erinaceus (Bull.) Pers.) was usually reported as well tolerated, with mild digestive complaints the most common. A small number of serious or allergic reports exist, all individual cases. "Well tolerated in small, short trials" is not the same as "proven safe for everyone": trials are small and often exclude people with other illnesses. Evidence label: reported reactions (case reports and trial side effects).
What was reported
| Reaction | What the source says | Kind of evidence |
|---|---|---|
| Stomach discomfort, diarrhea | A systematic review lists stomach discomfort, headache and allergic reactions as possible, though "commonly unreported".[1] In a 16-week trial, mild stomach discomfort and diarrhea occurred in 7 people on lion's mane and 6 on placebo.[1] | Trials; mild |
| Abdominal discomfort, nausea, skin rash | In a 49-week trial of erinacine A-enriched mycelium capsules, four people dropped out for these reasons.[2] A cancer center's lion's mane page also lists them.[3] | Trial |
| Severe breathing illness | A 63-year-old man developed acute respiratory distress syndrome; a lymphocyte stimulation test reacted strongly to the lion's mane extract he had taken, and he recovered with steroid treatment under mechanical ventilation. The authors called it the first report suggesting a causal link.[4] | Single case report |
| Anaphylaxis | An ALS review group noted one anaphylactic case after a patient ate fresh lion's mane mushroom.[5] | Single case, fresh mushroom |
| Skin allergy | A report titled as occupational allergic contact dermatitis from the mushroom exists.[6] | Single case; workplace exposure |
| Menstrual change | One trial listed epimenorrhea (more frequent periods) in its side-effect table.[1] | Trial; unclear |
Respiratory allergy or asthma from spores or powders: Proper evidence not found for lion's mane specifically. We searched PubMed for Hericium with asthma, hypersensitivity and anaphylaxis and found only the cases above. For mushroom allergy in general, see mushroom allergy and food intolerance.
What animal toxicity tests found
In rats, one study of lion's mane and turkey tail powders found no subchronic toxicity at doses up to 2000 mg/kg body weight a day, and no genotoxicity. Two authors were employed by the ingredient company.[7] Animal results do not show safety in people.
Who should ask a clinician or pharmacist first
- Mushroom allergy or past reactions to mushrooms, or asthma or lung disease, since the serious reports above involved breathing and allergy.
- Medicines: documented interactions: Proper evidence not found in the sources we read; this is not proof of safety. Ask a pharmacist; see how interactions work.
- Pregnancy, breastfeeding, children: Proper evidence not found for lion's mane supplements in the sources we read. See lion's mane in pregnancy, breastfeeding and children.
- Before surgery or with a bleeding or blood-sugar condition: tell the surgical team about every supplement. Specific lion's mane bleeding data were not found in the sources we read.
- Liver or kidney disease: no lion's mane liver or kidney reports were found in the sources we read, which is not proof of safety.
Quality matters
Products differ in species, part (fruiting body or mycelium on grain) and fillers, and a label may not match the contents. See quality testing and certifications.
If you think a product caused a problem
Stop using the product and talk to a clinician, and report it: side effects, allergic reactions and reporting.
Related
Lion's mane guide | Mushroom supplement side effects by type
Frequently asked questions
What are the most common side effects of lion's mane?
Mild stomach discomfort, diarrhea and headache were reported in some trials, though a review said they are commonly unreported.[1]
Can lion's mane cause an allergic reaction?
Yes, individual reports exist: one anaphylaxis case after fresh mushroom[5] and one lung illness with a positive lymphocyte test.[4]
Is lion's mane safe for long-term use?
Proper evidence not found for multi-year human safety. The longest trial in our sources ran 49 weeks.[2]
Can I take lion's mane with my medicines?
No interaction data were found in the sources we read, which is not proof of safety. Ask a pharmacist.
Should I stop lion's mane if I get a rash?
Stop the product, ask a clinician, and seek urgent help if breathing or swallowing is affected.[2]