context: Reishi mushrooms are among several medicinal mushrooms that have been used for hundreds of years, mainly in Asian countries, for treatment of infections. More recently, they have also been used in the treatment of pulmonary diseases and cancer. Medicinal mushrooms have been approved adjuncts to standard cancer treatments in Japan and China for more than 30 years and have an extensive clinical history of safe use as single agents or combined with chemotherapy. The reishi mushroom is also known as lingzhi. Reishi mushroom has been used to help enhance the immune system, reduce stress, improve sleep, and lessen fatigue. People also take reishi mushroom for health conditions such as: High blood pressure High cholesterol Cardiovascular disease Liver or kidney disease Respiratory diseases (such as asthma) Viral infections (such as the flu) HIV/ AIDS Cancer and support during chemotherapy Pain during and after a shingles outbreak Building strength and stamina Fatigue There is some scientific evidence of its effectiveness, including lab research and some small human studies. Researchers are beginning to look at the chemical makeup of this mushroom to better understand how and whether it really works for each of these conditions. Doses may depend upon factors that include: Your age Condition for which the mushroom is being prescribed Form of the mushroom Your overall health But each of these is a typical oral daily dose: 1.5 to 9 grams of crude dried mushroom 1 to 1.5 grams of reishi powder 1 milliliter of reishi solution (tincture) Reishi mushroom is cultivated and sold as a food, but it may be tough and bitter. When taken for health reasons, it is usually dried or taken as an extract, such as in the form of: Liquid Capsule Powder Side effects. When used over three to six months, reishi mushroom can cause an allergic reaction associated with dryness in your: Mouth Throat Nasal passages It can also cause: Dizziness Itchiness Rash Headaches Stomach upset Nosebleed Bloody stools Risks. Taking reishi mushroom may be riskier if you have low blood pressure or are taking therapy to raise your blood pressure, are taking diabetes medications, or have immune system disorders or medications. Higher doses of reishi mushroom might make bleeding more likely in people who have a very low platelet count. Also, avoid using reishi mushroom if you are pregnant or breastfeeding, because there hasn't been enough study on its safety in these circumstances. Interactions. Reishi mushroom may increase the risk of bleeding. Talk to your doctor before taking reishi mushroom if you are using anticoagulant or antiplatelet drugs such as: Aspirin Nonsteroidal anti-inflammatory drugs ( NSAIDs) Warfarin Heparin Reishi mushroom may also interact with high blood pressure medications. Also discuss possible interactions if you are taking other herbs or supplements that may prevent normal blood clotting or lower blood pressure. Ginkgo and fish oil are two examples. Tell your doctor about any supplements you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with medications or foods. He or she can let you know if the supplement might raise your risk. The U. S. Food and Drug Administration ( FDA) does regulate dietary supplements; however, it treats them like foods rather than medications. Unlike drug manufacturers, the makers of supplements don't have to show their products are safe or effective before selling them on the market.