Cordyceps: the Himalayan stamina mushroom

Cordyceps is a genus of fungi. It is not a plant, and it does not look like a mushroom in the usual cap and stalk sense. Mycologists count several hundred species, with estimates running from about 400 to more than 750 depending on how they are classified. Most live as parasites on insects and other arthropods.

The best known is the Chinese caterpillar fungus. It grows on the Tibetan plateau and in the Himalayas of Nepal, Bhutan and northern India, usually above 3,000 metres. Its spores infect ghost moth caterpillars living in the soil. Over winter the fungus fills the larva's body, and in spring a thin brown stalk pushes up through the ground from the caterpillar's head. Harvesters dig up the stalk with the mummified larva still attached.

That life cycle gave it its names. In Tibetan it is yartsa gunbu, meaning "summer grass, winter worm". In Chinese it is dong chong xia cao, which means much the same. Western sellers sometimes call it "Himalayan Viagra", a nickname that owes more to marketing than to evidence.

A related genus, Ophiocordyceps, includes the zombie ant fungus that inspired the TV series The Last of Us. None of these fungi can infect people, and the cordyceps sold in supplements is grown in labs on grain or in liquid broth rather than on insects.

Three names turn up on labels, and they are different things.

• Cordyceps sinensis (Ophiocordyceps sinensis). The wild caterpillar fungus. DNA work led taxonomists to move it into the genus Ophiocordyceps in 2007, though most labels still say Cordyceps sinensis. Wild stock is scarce. Top grades sell for tens of thousands of pounds a kilo, which is why it is often compared with gold by weight, and the IUCN Red List assesses the species as Vulnerable because of overharvesting, habitat loss and climate change.
• Cs-4. A strain isolated from wild caterpillar fungus in China in the 1980s and grown by fermentation. It has since been identified as a separate fungus, Paecilomyces hepiali (also listed as Samsoniella hepiali). Many of the older exercise trials used Cs-4, and in China a Cs-4 product has been approved for hospital use.
• Cordyceps militaris. An orange, club shaped species that is easy to grow on rice or in broth and is naturally richer in cordycepin. It is sold widely abroad, but it is listed as a novel food in the EU and Great Britain (more on that below).

Almost all the "Cordyceps sinensis" on sale today is cultivated mycelium, or mycelium grown on grain, rather than wild fruiting body. That is normal, but it means two products with the same name on the front can contain quite different material.

You will find cordyceps as loose powder, capsules, tablets, liquid extracts, mushroom coffee blends and gummies.

Researchers have picked out several groups of compounds that might explain what cordyceps does in lab studies.

• Cordycepin (3'-deoxyadenosine). A close chemical cousin of adenosine, which is one of the building blocks of ATP, the molecule cells use to carry energy. Cordyceps militaris contains much more cordycepin than cultivated sinensis.
• Adenosine and other nucleosides. Often used as quality markers when a manufacturer tests a batch.
• Polysaccharides, including beta glucans. Long sugar chains found in most functional mushrooms and the focus of most immune research in cells and animals.
• Sterols such as ergosterol. The fungal version of cholesterol, which turns into vitamin D2 under UV light.
• Protein, amino acids, polyphenols and minerals. Present in modest amounts, as in other edible fungi.

The level of each compound changes with species, strain, growing medium and whether a product uses fruiting body or mycelium. A lab result for purified cordycepin in a dish tells you very little about what a spoonful of powder does in a person.

The first detailed written record comes from Tibet. A fifteenth century text by the physician Zurkhar Nyamnyi Dorje, usually translated as An Ocean of Aphrodisiacal Qualities, describes yartsa gunbu as a tonic. Chinese herbal texts took it up later, and by the Qing dynasty it was a prized and costly remedy.

In traditional Chinese medicine it was used for tiredness, weakness after illness, coughs, kidney complaints and low sex drive. It was often cooked into soup with duck or chicken, or steeped in rice wine. Himalayan herders tell a story about yaks growing livelier after grazing where the fungus grew, and that tale is still repeated as the reason people first tried it.

Cordyceps reached Western newspapers in 1993, when a group of Chinese women runners broke several world records at their National Games. Their coach said the squad drank a tonic that included caterpillar fungus. Later reporting raised doping allegations about that team, so the episode tells us little about the fungus, but it fixed cordyceps' reputation as a stamina aid.

The wild harvest is now a major source of cash income for families on the Tibetan plateau and in Nepal. Cultivated cordyceps, meanwhile, is sold around the world, and it is popular with people who want a morning routine that does not depend on coffee.

Exercise is where cordyceps has the most human research, and the results point in both directions.

The theory is that cordycepin and adenosine might affect how cells make ATP, and that cordyceps might change how the body uses oxygen. Rodent studies report longer swimming times and slightly higher grip strength. Human trials give a mixed picture:

• Chen and colleagues, 2010. 20 healthy adults aged 50 to 75 took 333mg of Cs-4 three times a day, or a placebo, for 12 weeks. In the Cs-4 group the metabolic threshold (the point where lactate starts to build up) rose by 10.5% and the ventilatory threshold by 8.5%. The placebo group showed no significant change. Maximal oxygen uptake, or VO2 max, did not change in either group.
• Hirsch and colleagues, 2017. 28 young adults took 4g a day of a mushroom blend containing Cordyceps militaris, or a placebo. After one week there were no significant differences. Ten people carried on for three weeks, and in that small group VO2 max and time to exhaustion rose compared with placebo. Because the product was a blend, the result cannot be pinned on cordyceps alone.
• Dewi and colleagues, 2024. 14 young adults took 1g of Cordyceps sinensis or a placebo before hard interval cycling, then swapped. Muscle biopsies showed less damage related cell build up and earlier arrival of stem cells after the cordyceps dose. The trial measured tissue markers, not performance.
• Parcell and colleagues, 2004. 22 trained male cyclists took 3g a day of Cs-4 for five weeks. Aerobic capacity and time trial results were no different from placebo.
• Earnest and colleagues, 2004. 17 amateur cyclists took a commercial formula of Cs-4 and Rhodiola rosea for two weeks. No performance measure changed compared with placebo. A smaller trial by Colson and colleagues in 2005, with 8 men on a similar blend, found no difference in muscle oxygen levels either.

Set side by side, the positive trials were in untrained or older adults and the null trials were mostly in trained cyclists. All were small, several tested blends, and none tested a gummy.

Most immune research on cordyceps is in cells and mice, where its polysaccharides change the activity of macrophages and natural killer (NK) cells. A few human trials have measured immune markers in healthy adults:

• Kang and colleagues, 2015. 79 healthy Korean men took 1.5g a day of Cordyceps militaris or a placebo for four weeks. NK cell activity, lymphocyte proliferation and two signalling proteins, IL-2 and interferon gamma, rose more in the cordyceps group. No significant side effects were reported.
• Jung and colleagues, 2019. 79 healthy adults took 1.68g a day of a cordyceps mycelium extract (Paecilomyces hepiali) or a placebo for eight weeks. NK cell activity rose by about 39% from baseline relative to placebo.
• Ontawong and colleagues, 2024. 40 healthy Thai adults drank a fermented Cordyceps militaris drink or a placebo for eight weeks. NK activity rose in some subgroups, and liver, kidney and blood safety tests stayed normal.

All three trials measured markers in blood. None tracked whether people caught fewer colds or recovered faster, and a higher NK reading is not the same thing as a lower risk of illness. In the UK a supplement can only make an immunity claim if it is authorised, and no such claim is authorised for cordyceps.

Many articles list a long run of cordyceps benefits. Here is where each one actually stands.

• Kidney health. A 2014 Cochrane review pooled 22 Chinese trials with 1,746 people who had chronic kidney disease. Adding cordyceps to standard treatment was linked with lower serum creatinine and less protein in the urine, but the reviewers judged the evidence low quality and said firm conclusions were not possible. This was a hospital setting and is no reason to self-treat.
• Blood sugar and cholesterol. Mouse and rat studies report lower blood glucose and lower blood fats. There are no good human trials.
• Heart rhythm and blood pressure. Adenosine affects heart rate, and animal studies have looked at heart enlargement and triglycerides. Chinese clinical trials in people with arrhythmias have been reviewed, but they are small and were not testing supplements.
• Inflammation, asthma and allergy. In cell cultures, cordyceps extracts lowered inflammatory proteins, and animal work has looked at arthritis and airway inflammation. Human data are thin.
• Ageing, skin and antioxidants. Cordyceps contains antioxidant compounds, and lab and animal work has looked at oxidative stress and collagen. Antioxidant activity in a test tube does not show an anti-ageing effect in people.
• Stress. Some sellers call cordyceps an adaptogen that raises corticosteroid output and resilience to stress. That idea rests on animal work, and no controlled human trial has tested it.
• Sex drive and testosterone. This is the oldest traditional use. The evidence comes mainly from animal studies and a few small, older human reports. No reliable trial shows a change in libido, sperm or testosterone.
• Viruses, bones and fatigue. Cordycepin has been screened against viruses, including in COVID-19 lab research, and animal studies have looked at bone loss and tiredness. None of this has been shown in people.

Pulling the human research together gives a short list of things we can say with some confidence.

• Small randomised trials in healthy adults have given 1g to 4g a day for up to 12 weeks, with few reported side effects.
• Two trials in untrained or older adults found changes in exercise measures such as ventilatory threshold, and one found faster muscle repair markers after a single 1g dose.
• Three trials in healthy adults found higher NK cell activity after four to eight weeks.

And a longer list of things the research does not show:

• That cordyceps changes performance in trained athletes. Three trials in cyclists found no difference.
• That any lab change translates into fewer infections, energy people can feel, a higher sex drive or a longer life.
• Which form works best. Trials used Cs-4, militaris, sinensis powder, mycelium extracts and multi ingredient blends, and a result from one cannot be carried over to another.
• Safety over periods longer than about three months.

Most trials tested a single commercial product, and few have been repeated by independent groups. Larger, longer studies in ordinary adults are the missing piece.

There is no official dose. The amounts used in human trials give a rough guide:

• 1g as a single dose before exercise (Dewi, 2024)
• 1g a day split into three doses (Chen, 2010)
• 1.5g to 1.68g a day in the immune trials
• 3g to 4g a day in the cyclist and blend trials

Reviews often quote 1,000mg to 4,000mg a day, and some European brands suggest about 1,200mg of powder a day, split across meals and taken with plenty of water. Concentrated extracts are measured differently. A 10:1 extract uses ten grams of raw mushroom to make one gram of extract, so the milligram figure on an extract label cannot be compared directly with a powder.

Most people take cordyceps in the morning or before exercise, in keeping with its traditional link with stamina. Taking it with food may be gentler on the stomach. The trials that found changes ran for one to twelve weeks, so a few weeks of daily use is a fair test. Stick to the dose on the label and avoid stacking several cordyceps products at once.

Cordyceps was well tolerated in the published trials. Reported side effects are mild and uncommon:

• upset stomach, nausea, bloating or diarrhoea
• dry mouth
• loss of appetite
• skin rash

Allergic reactions are possible, particularly in people allergic to moulds or other fungi. Stop taking it and get medical attention straight away if you notice swelling of the lips, tongue or throat, wheezing or difficulty breathing. In the UK, call 999 for a severe reaction.

Speak to a GP or pharmacist before taking cordyceps if you:

• are pregnant, trying to conceive or breastfeeding, as there is no safety data
• take blood thinners such as warfarin, apixaban, clopidogrel or daily aspirin, or have a bleeding disorder, because cordyceps may slow blood clotting and add to their effect
• take diabetes medicines, including insulin or metformin, because it lowered blood sugar in mouse and rat studies and could add to their effect
• take immunosuppressants such as ciclosporin, tacrolimus or long term steroids, for example after a transplant
• have an autoimmune condition such as rheumatoid arthritis, lupus or multiple sclerosis, since cordyceps may increase immune activity
• have surgery coming up (stop at least two weeks before and tell your surgeon)
• are buying for a child

Purity matters as well. In 2016 China's food and drug regulator warned that tested samples of wild caterpillar fungus contained arsenic well above its limit for health foods, so buy from a seller who can show batch testing for heavy metals. If you think a supplement has caused a side effect, you can report it to the MHRA through the Yellow Card scheme.

Cordyceps is sold in the UK as a food supplement, which means it is regulated as a food rather than a medicine. A few UK points are worth knowing.

• Claims. Food can only carry health claims that appear on the Great Britain nutrition and health claims register. No claim for cordyceps is on that register, so a UK seller cannot lawfully promise energy, stamina or immunity from it.
• Novel food status. The Novel Food Catalogue lists the mycelium and fruiting body of Cordyceps sinensis as not novel for use in food supplements. Cordyceps militaris is listed as novel, and the Food Standards Agency treats it as needing authorisation before it can be sold as food in Great Britain.
• NHS guidance. The NHS has no page on cordyceps, so its general advice on supplements applies: check with a GP or pharmacist first if you take regular medicines or have a long term condition.
• Sport. Cordyceps is not on the World Anti-Doping Agency prohibited list. UK Anti-Doping still warns that any supplement can be contaminated, so athletes in tested sport should choose batch tested products, such as those certified by Informed Sport.
• Where it is sold. Health food chains, pharmacies, online specialists and mushroom coffee brands all sell cordyceps, as powders, capsules, tinctures, drinks and gummies.

When you compare products, look for:

• the species named on the label (sinensis, Cs-4 or militaris)
• whether it is fruiting body, mycelium or mycelium on grain
• the amount per serving and, for extracts, the ratio
• a full ingredient list and a UK business address
• evidence of third party testing for heavy metals and microbes
• a company that describes studies accurately and avoids countdown timers or miracle promises

Starshroooms contain whole Cordyceps sinensis powder alongside five other mushrooms (Lion's Mane 2:1, Reishi 20:1, Chaga 10:1, Maitake 10:1 and Tremella) and full spectrum Panax Ginseng. Because the cordyceps is a whole mushroom powder rather than a concentrated extract, it has no extract ratio on the label.

Each two gummy serving also contains 12mg of pantothenic acid (vitamin B5, 200% of the NRV) and 100µg of iodine (67% of the NRV). Unlike cordyceps, these nutrients have authorised health claims:

• pantothenic acid contributes to the reduction of tiredness and fatigue
• pantothenic acid contributes to normal mental performance
• iodine contributes to normal cognitive function

The gummies are blackcurrant flavoured, vegan, set with fruit pectin, and free from caffeine and gelatine. Most people take two with breakfast. A 60 gummy pack costs £24.99 and lasts a month, and a 10 gummy trial pack is £4.99. The studies on this page looked at cordyceps on its own, in different forms and amounts, and none of them tested our gummies.

For the other ingredients, read our guides to Lion's Mane, Reishi, Chaga, Maitake, Tremella and Panax Ginseng, see every study we cite on the research page, or browse all our mushroom gummies.