Cordyceps is a fungus that lives on certain caterpillars in the high mountain regions of China. Natural cordyceps is hard to get and may be expensive. Most supplements are made with cordyceps grown in a laboratory.

Cordyceps is most commonly used for kidney disorders and male sexual problems. It is also used after a kidney transplant. It is also used for liver problems, improving athletic performance, and many other conditions.
 
Cordyceps might improve immunity by stimulating cells and specific chemicals in the immune system. It may also have activity against cancer cells and may shrink tumor size, particularly with lung or skin cancers.