Although Cordyceps sinensis is often described as an herb, it’s actually a combination of a parasitic fungus and the larvae of a moth (a caterpillar). The fungus attacks the caterpillar and destroys it from within. The remaining structures of the caterpillar along with the fungus are dried and sold as cordyceps.

Cordyceps has a long history of use in China as a “tonic,” a substance said to generally strengthen the body, particularly following illness. It was also used to treat bronchitis, kidney failure, and tuberculosis.1

Cordyceps is widely marketed today as treatment for many conditions. However, there is no reliable scientific evidence that it actually provides any medical benefits.

Most research on cordyceps was done in China and is not up to modern scientific standards. In general, double-blind, placebo-controlled studies are the most reliable form of evidence. (For information on the reasons why, seeWhy Does This Database Rely on Double-blind Studies?) However, such studies have to be performed and reported according to certain standards. Although several double-blind studies have been reported on cordyceps, they all fall considerably short of the level necessary for scientific validity. These somewhat dubious double-blind trials hint that cordyceps might be helpful for reducinghigh cholesterol2 and improving male sexual function.3,4

Evidence is more negative than positive regarding whether cordyceps is helpful for enhancing sports performance.5-7

Weak evidence hints that cordyceps may modulate the immune system, which means that it stimulates some aspects of the immune system while suppressing others.8-13

On this basis, it has been tried in China as an aid in organ transplant surgery 14 and for the treatment of viral hepatitis15,16 and lupus.17,18

Highly preliminary test-tube and animal studies hint that cordyceps may help fight stress,19 control blood sugar levels (potentially making it useful in diabetes),20-22reduce cancer risk,23 lower high blood pressure,24 and help protect the kidney against damage caused by the drugs cyclosporin and gentamycin.25-27

Other test-tube studies hint that cordyceps may stimulate production of hormones, such as cortisone and testosterone.28-33 However, contrary to what some websites say, these studies are far too preliminary to indicate any therapeutic hormonal effect.