It isn’t known if Chaga is safe or what the possible side effects might be. However there are certain conditions, where you want to be extra careful. Chaga might cause the immune system to become more active, which could increase the symptoms of auto-immune diseases, like MS, lupus, RA and others. If you have one of these conditions, it’s best to avoid using Chaga. Don’t use it during pregnancy and breast feeding because there is not enough reliable information about the safety of taking Chaga during this time. And also taking Chaga might increase the risk of bleeding in people with bleeding disorders. Definitely stop using Chaga 2 weeks before any surgery because it might increase the risk of bleeding during and after surgery. You should also be careful if you have diabetes, because Chaga can lower your blood sugar levels, so monitor them carefully.