Skip to content

Coming soon. The store is not open yet.

Menu
Full Measure

Ingredient guide

Cordyceps side effects: what trials and case reports show

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

Trials of cordyceps at 1 to 4 g a day reported few side effects, and NIH's LiverTox rates it an unlikely cause of liver injury. Rare problems on record are one liver case after five years of daily use and lead from contaminated powder. Safety in pregnancy and breastfeeding has not been studied.1,2,3,4

Key facts

  • In a 3-month study of 49 adults taking 1.05 g a day of a related species, liver and kidney blood tests did not change.2
  • Only 3 of 14 mushroom trials in athletes mentioned adverse events at all.5
  • Contaminated cordyceps powder in two cases from Taiwan held up to 20,000 ppm of lead.4
  • A cordyceps immune trial excluded women who were pregnant or breastfeeding.6

What the trials reported

Trials of 1 to 4 g a day reported few side effects. In a 3-month study of 1.05 g a day of a related species, liver and kidney blood tests did not change and no one reported side effects.2,6,7

In the immune trials there were no significant adverse reactions with 1.5 g a day for 4 weeks, and no serious adverse events with 1.68 g a day for 8 weeks. The drink trial found no change in safety blood tests, including liver enzymes and creatinine, over 8 weeks.6,7,8

In a 2025 review of 14 trials of mushroom supplements in athletes, only 3 mentioned adverse events, so mild complaints may have gone unrecorded.5

Liver

LiverTox finds no link between cordyceps and raised liver enzymes or sudden liver injury in people, and rates it an unlikely cause of liver injury.1

Rare: hepatoportal sclerosis, a disorder of the small veins in the liver, in an 81-year-old woman who had taken a cordyceps tablet daily for 5 years. Doctors judged cordyceps a possible cause, and she improved after stopping.3

The doctors judged that link possible, not proven, and it came after five years of daily use. If you have liver disease, ask your doctor before starting cordyceps.3

Kidneys

Kidney blood tests did not change in the 3-month safety study of a related species or in the 8-week drink trial in healthy adults. If you have kidney disease, ask your doctor before taking cordyceps.2,8

Contamination

Lead poisoning from contaminated cordyceps powder: two cases in Taiwan, where the powder held up to 20,000 ppm of lead. Blood lead returned to normal after they stopped taking it.4

One of the two people had lost appetite and showed signs of lead poisoning, and was treated to remove the lead. The other had no symptoms and recovered after simply stopping the powder.4

Blood thinners, blood sugar and the immune system

No official source we checked lists a medicine that interacts with cordyceps. Three cautions come from other research instead:1

  • Bleeding: cordycepin and a Cordyceps militaris extract reduced platelet clumping in laboratory and animal tests, though the extract did not change standard clotting times. Ask first if you take a blood thinner or antiplatelet medicine, or before surgery.9,10
  • Blood sugar: a Cordyceps militaris polysaccharide lowered blood sugar in mice, while a drink trial in healthy adults found no change. Ask first if you take insulin or another medicine that lowers blood sugar.8,11
  • Immune system: cordyceps raised natural killer cell activity in small trials. Ask first if you take medicines that suppress the immune system, for example after a transplant, or have an autoimmune condition.6,7

Pregnancy and breastfeeding

We found no human study of cordyceps in pregnancy or breastfeeding. In a 2026 laboratory study, cordycepin reduced the ability of human placental cells to invade tissue, a step the placenta needs to form normally. That was in cells, not in pregnant women, but it is one more reason to avoid cordyceps in pregnancy unless your doctor agrees.12

Side effects in men and women, and mood

None of the trials we read reported side effects specific to men or to women. In young men, a training supplement containing cordyceps and rhodiola did not change hormone levels over 14 weeks.13

We found no trial that reported anxiety as a side effect, but most trials did not track side effects closely. If you feel anxious or restless after starting cordyceps, stop it and talk to your doctor.5

How much is too much

No upper limit is set. Most trials used 1 to 4 g a day, and a 2026 review of Cordyceps militaris trials, some testing mixtures, lists amounts up to 12 g a day for 1 to 16 weeks. A safety study of a related species ran 3 months at 1.05 g a day. NIH's LiverTox rates cordyceps an unlikely cause of liver injury.1,2,14,15,16

Questions people ask

Is cordyceps safe for humans?

In trials of up to a few months, adults taking 1 to 4 g a day reported few side effects, and LiverTox rates cordyceps an unlikely cause of liver injury. It has not been studied in pregnancy, breastfeeding or children.1,2,15

Is cordyceps safe to eat?

The wild fungus and its caterpillar have been used in traditional Chinese medicine for centuries, and farmed Cordyceps militaris has been given to people as a drink in trials. Most supplements are lab-grown mycelium rather than the wild fungus, so buy from a seller who names the species and form.1,8,17

Who should not take cordyceps?

Anyone who is allergic to mushrooms or molds. People who are pregnant, breastfeeding or under 18, or who take a blood thinner, insulin or immune-suppressing medicine, or who have liver disease, should ask a doctor first.3,9,11

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line

Sources

  1. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Cordyceps. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases. Last update July 23, 2026. Opened 2026-10-01.
  2. Tsai YS, Hsu JH, Lin DP, et al. Safety assessment of HEA-enriched Cordyceps cicadae mycelium: a randomized clinical trial. J Am Coll Nutr. 2021;40(2):127-132. Opened 2026-10-07.
  3. Kaur B, Vipani A, Trivedi H, et al. Traditional Chinese medicine, Cordyceps, related to hepatoportal sclerosis. ACG Case Rep J. 2023;10(12):e01206. Opened 2026-10-07.
  4. Wu TN, Yang KC, Wang CM, et al. Lead poisoning caused by contaminated Cordyceps, a Chinese herbal medicine: two case reports. Sci Total Environ. 1996;182(1-3):193-195. Opened 2026-10-07.
  5. Shu MY, Zhang XC, Zuo L, Jiang FL, Liang J, Li F. Effects of fungal supplementation on endurance, immune function, and hematological profiles in adult athletes: a systematic review and meta-analysis. Front Nutr. 2025;12:1670416. Opened 2026-10-07.
  6. Jung SJ, Jung ES, Choi EK, Sin HS, Ha KC, Chae SW. Immunomodulatory effects of a mycelium extract of Cordyceps (Paecilomyces hepiali; CBG-CS-2): a randomized and double-blind clinical trial. BMC Complement Altern Med. 2019;19(1):77. Opened 2026-10-07.
  7. Kang HJ, Baik HW, Kim SJ, et al. Cordyceps militaris enhances cell-mediated immunity in healthy Korean men. J Med Food. 2015;18(10):1164-1172. Opened 2026-10-07.
  8. Ontawong A, Pengnet S, Thim-Uam A, et al. A randomized controlled clinical trial examining the effects of Cordyceps militaris beverage on the immune response in healthy adults. Sci Rep. 2024;14(1):7994. Opened 2026-10-07.
  9. Cho HJ, Cho JY, Rhee MH, Park HJ. Cordycepin (3'-deoxyadenosine) inhibits human platelet aggregation in a cyclic AMP- and cyclic GMP-dependent manner. Eur J Pharmacol. 2007;558(1-3):43-51. Opened 2026-10-07.
  10. Choi E, Oh J, Sung GH. Antithrombotic and antiplatelet effects of Cordyceps militaris. Mycobiology. 2020;48(3):228-232. Opened 2026-10-07.
  11. Sun H, Yu X, Li T, Zhu Z. Structure and hypoglycemic activity of a novel exopolysaccharide of Cordyceps militaris. Int J Biol Macromol. 2021;166:496-508. Opened 2026-10-07.
  12. Guo M, Luo S, Bi B, et al. Cordycepin inhibits human extravillous trophoblast invasion by suppressing snail-mediated MMP2 expression. Tissue Cell. 2026;100:103381. Opened 2026-10-07.
  13. Kreipke VC, Moffatt RJ, Tanner CJ, Ormsbee MJ. Effects of concurrent training and a multi-ingredient performance supplement containing Rhodiola rosea and Cordyceps sinensis on body composition, performance, and health in active men. J Diet Suppl. 2021;18(6):597-613. Opened 2026-10-07.
  14. Chen S, Li Z, Krochmal R, Abrazado M, Kim W, Cooper CB. Effect of Cs-4 (Cordyceps sinensis) on exercise performance in healthy older subjects: a double-blind, placebo-controlled trial. J Altern Complement Med. 2010;16(5):585-590. Opened 2026-10-07.
  15. Hirsch KR, Smith-Ryan AE, Roelofs EJ, Trexler ET, Mock MG. Cordyceps militaris improves tolerance to high-intensity exercise after acute and chronic supplementation. J Diet Suppl. 2017;14(1):42-53. Opened 2026-10-07.
  16. Jędrejko M, Jędrejko K, Granda D, Kała K, Pokrywka A, Muszyńska B. Current evidence of ergogenic and post-exercise recovery effects of dietary supplementation with Cordyceps militaris in humans: a narrative review. Nutrients. 2026;18(5):781. Opened 2026-10-07.
  17. Paterson RR. Cordyceps: a traditional Chinese medicine and another fungal therapeutic biofactory? Phytochemistry. 2008;69(7):1469-1495. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.