The most common reishi mushroom side effects reported include upset stomach, dizziness, and skin rashes during the first ten to 20 days of intake. It has been suggested that these side effects are due to the accumulated toxins in the body being excreted or "pushed out." For most users, the side effects of reishi mushrooms are almost always temporary. Existing conditions such as pregnancy, low blood pressure, and anemia may increase the risk of more serious side effects.
In most people, the use of reishi mushroom is completely safe. The only side effects experienced are mild and temporary, with the benefits reportedly outweighing the disadvantages. It is recommended that a person begin slowly with small doses of about 1 teaspoon (5 ml) of reishi per day either in capsule, dried herb, or tea form. From this point, the daily amount can be gradually increased up to as much as 10 teaspoons (50 ml) throughout the day. The correct dose is different for each person, so it may be beneficial to speak with a holistic medical professional before attempting to find the perfect dose.
Most common reishi mushroom side effects are referred to as detox symptoms. As toxins within the body are stirred up and expelled at a more rapid rate than normal, it is suggested, certain symptoms may occur. Nausea, diarrhea, and general upset stomach are very common to experience within the first couple of weeks, depending on how long the "cleaning up" process may take. Sometimes the reishi mushroom can also affect the skin, creating a rash which may be itchy. Drinking lots of water and cleansing juices like cranberry may help combat internal symptoms, and topical treatments such as coconut oil and aloe vera gel may help alleviate external symptoms.
Studies have not been very conclusive about the side effects of these mushrooms during pregnancy or breast feeding. As some serious side effects such as lowered blood pressure or increased chances of bleeding have been reported, it may be safe to not use the herb while pregnant or breast feeding. Someone who already has low blood pressure may also wish to avoid reishi mushrooms, as their use may further complicate the condition. Any conditions in which the blood does not clot properly may also need to be seriously considered before a person begins using reishi mushrooms. Blood which does not clot the way it should may not clot at all when high doses of reishi are being used.
In most cases, the most common reishi mushroom side effects are usually nothing to worry about in a relatively healthy individual. Reishi mushrooms have been shown to boost the immune system, fight heart disease, and even calm stress and nerves. This herb should not be taken with certain medications, however, such as those for diabetes. When in doubt, it is usually recommended that a person speak with her doctor before beginning holistic treatment. The reishi mushroom side effects and severity are different in each person, depending on the person's health and dose taken.