If you are taking any of the following medications, you should not use echinacea without first talking to your healthcare provider:

Econazole echinacea may be useful in combination with econazole, an antifungal agent used to treat yeast infections (such as athlete's foot). When echinacea is used together with econazole, recurrence rates of these infections may be reduced.

Immunosuppressants Immunosuppressants refers to a group of medications that are used for two main purposes -- treat cancer and suppress the immune system following organ transplant so that the new organ is not rejected. Because echinacea can enhance immune function, people should not use the herb with immunosuppressive medications, especially when taken for organ transplant.

In terms of cancer treatment, a couple of test tube studies imply that echinacea may be useful when used in combination with cyclophosphamide, one medication in this class. Using echinacea with this or other chemotherapy agents that act as immunosuppressants, may allow the cancer-fighting medicines to kill the tumors while still protecting the immune system. If this theory proves to be correct then echinacea could possibly prevent many of the side effects of chemotherapy.