Don’t use it during pregnancy and breast feeding because there is not enough reliable information about the safety of taking Reishi during this time. And also Reishi might increase the risk of bleeding in some people with bleeding disorders. If you have a condition called thrombocytopenia, don’t use Reishi as well. Reishi also seems to be able to lower blood pressure. this is a concern that it might make low blood pressure worse and could interfere with treatment, so don’t use it, if your blood pressure is too low. Taking Reishi might increase the risk of bleeding during surgery, so stop using Reishi at least two weeks before scheduled surgery.