Quick answer

Cordyceps is a group of fungi that grow on insects; supplements use farmed Cordyceps militaris or lab-grown mycelium. Small trials of 1 to 4 g a day found mixed effects on exercise tests and on immune cell activity, so the evidence is graded early. NIH's LiverTox says no claimed benefit has been shown convincingly.^1,2,3,4,5

Key facts

Typical cordyceps products are taken at 0.5 to 4 g a day.¹
The wild caterpillar fungus has been harvested so heavily that it is scarce, and most products are grown instead.^1,6,7
In trained cyclists, 3 g a day for 5 weeks changed no performance measure.⁵
NIH's LiverTox rates cordyceps an unlikely cause of liver injury.¹

What cordyceps is

Cordyceps is the common name for several fungi that live on insects, chiefly Ophiocordyceps sinensis and Cordyceps militaris.¹

It has been part of traditional Chinese medicine for centuries, where LiverTox notes it was used for fatigue and ageing among other complaints. Research in healthy people has mostly looked at two things: exercise capacity and the immune system.^1,6,8

NIH's LiverTox says none of cordyceps' claimed benefits has been shown convincingly in human trials.¹

What cordyceps does to insects

The fungus that makes ants climb plants and clamp their jaws onto a leaf or twig before they die is a different group of species, Ophiocordyceps unilateralis. It fills the ant's jaw muscles but not its brain, and each species tends to attack particular kinds of ant.^9,10

That is the fungus behind the zombie stories. The species sold as supplements are not collected from insects at all: they are grown in laboratories or farmed.^1,3,10

What the studies in people found

Two effects have enough human research to show, and both are graded early. The trials were small, often used blends, and disagree with each other, so the grade reflects how little is settled rather than the size of any effect.

May support aerobic exercise capacity at 1 to 4 g a day taken for several weeks; results disagree, including in trained athletes*^2,3,5,8,11

Early evidence

In 20 adults aged 50 to 75, a cultured cordyceps mycelium (Cs-4) at 333 mg three times a day for 12 weeks raised two exercise thresholds by 8.5% and 10.5%, with no change in maximal oxygen uptake. In 28 young adults, 4 g a day of a mushroom blend containing Cordyceps militaris made no difference after 1 week; in the 10 who continued for 3 weeks, maximal oxygen uptake rose compared with placebo. In 22 trained male cyclists, 3 g a day for 5 weeks changed nothing measured. A 2025 meta-analysis of two or three small trials found borderline gains, and a 2026 review called the Cordyceps militaris trials inconsistent.

Amount studied: About 1 to 4 g a day for 3 to 12 weeks

May raise natural killer cell activity, one measure of immune function, in healthy adults; whether this means fewer illnesses was not tested*^4,12,13

Early evidence

In 79 healthy Korean men, 1.5 g a day of Cordyceps militaris for 4 weeks raised natural killer cell activity and lymphocyte growth more than placebo. In 79 healthy adults, 1.68 g a day of a cordyceps mycelium extract (Paecilomyces hepiali) for 8 weeks raised natural killer cell activity by about 39% compared with placebo. In a 40-person trial of a Cordyceps militaris drink, activity rose in men by 4 weeks against their starting level and, compared with placebo, in women by 8 weeks. The trials were small and short, and none counted illnesses.

Amount studied: 1.5 to 1.7 g a day for 4 to 8 weeks

Natural killer cell activity is measured in a blood sample in the laboratory, and these trials used it as a marker of immune function. A higher reading is not the same as falling ill less often, and none of the trials counted illnesses.^4,12,13

Wild, lab-grown and farmed cordyceps

Ophiocordyceps sinensis, formerly Cordyceps sinensis, grows on caterpillars in the Himalayan region. The fungus and the dead caterpillar together have been used in traditional Chinese medicine for centuries, and heavy harvesting has made the wild fungus scarce and costly.^1,6,7

Most products sold as Cordyceps sinensis are not the wild fungus but a mycelium grown in the laboratory, such as the strain Cs-4. Some of these strains, such as Paecilomyces hepiali, are a related fungus first isolated from wild cordyceps.^1,12

Cordyceps militaris is a related species that is grown commercially and costs less than wild Ophiocordyceps sinensis. It contains cordycepin: one mycelium powder used in a trial held 1,373 mg per 100 g.^3,8,13

Several trials tested cordyceps mixed with rhodiola or with other mushrooms, so their results cannot be credited to cordyceps alone. Three such trials, in cyclists and in students, found no change in exercise results.^14,15,16

These are different materials. A label that says only cordyceps, or Cordyceps sinensis mycelium, does not tell you which strain was grown or how much cordycepin the powder holds.^1,13

How much people take

Most commercial cordyceps products are a laboratory-grown mycelium, taken at 0.5 to 4 g a day.¹

In the trials we read, exercise studies used about 1 to 4 g a day for 1 to 12 weeks, and immune studies about 1.5 to 1.7 g a day for 4 to 8 weeks. The dosage guide sets out each one.^2,3,4,12

What's in ours

Mushroom Complex contains 266 mg of Cordyceps sinensis mycelium powder a day, roughly a quarter of the smallest daily amount in the trials we read, alongside nine other mushrooms. We make no claim for it.²

Side effects, and who should ask first

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.^4,12,17

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.¹⁸

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.¹⁹

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.^1,2,3,11,17

Ask your doctor first if you are pregnant or breastfeeding, or under 18
Ask first if you take a blood thinner or antiplatelet medicine, or have surgery planned: cordycepin slowed platelet clumping in laboratory tests^20,21
Ask first if you take insulin or another medicine that lowers blood sugar: a cordyceps polysaccharide lowered it in mice²²
Ask first if you take medicines that suppress the immune system, for example after a transplant^4,12
Ask first if you have liver disease, and do not take it if you are allergic to mushrooms or molds¹⁸

No official source we checked lists a medicine that interacts with cordyceps, and none of the DailyMed labels we read for common blood thinners and antidepressants mentions it. The cautions above rest on laboratory, animal and small human studies, which is why they say to ask first.

Questions people ask

What does cordyceps do to the body?

In small trials it changed some exercise test results and the activity of natural killer cells, with findings that often disagree. LiverTox's view is that no claimed benefit has been shown convincingly in people.^1,2,4

What does cordyceps do for men?

Nothing specific to men has been shown. Several exercise trials enrolled only men, including trained cyclists who saw no change on 3 g a day, and a 14-week trial of a cordyceps and rhodiola product in young men found no change in hormone levels.^5,23

Is cordyceps a mushroom?

It is a fungus that is sold alongside mushrooms, but in the wild it grows on insects. Supplement makers grow the mycelium in laboratories or farm Cordyceps militaris instead.^1,3

Is cordyceps safe?

In trials lasting up to a few months it caused few side effects, and LiverTox rates it an unlikely cause of liver injury. Rare problems include one liver case after five years of daily use and lead poisoning from contaminated powder, so ask your doctor first if you have liver disease.^1,18,19

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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