There is evidence to suggest that Cordyceps may be useful as a performance enhancer, improving endurance, stamina and overall fitness. Cordyceps is given, traditionally, for a variety of respiratory problems. These include upper respiratory infections, bronchitis and asthma. The herbal remedy may increase the overall oxygen absorption abilities of the body, thereby improving oxygenation. Cordyceps may assist with the treatment of hepatitis B by increasing serum gamma globulin levels and bolstering the immune system. Cordyceps may also have antibiotic properties. Cordyceps is commonly used to improve liver and kidney function. Those with kidney and liver problems may benefit from using Cordyceps as a part of a treatment plan. Cordyceps may have tumor-reducing properties. The supplement may stimulate an auto-immune response that reduces tumor size.