Comfrey can be used internally ONLY after cleansing the liver and bowels.
If an individual has been taking prescription drugs or drinking, etc., (making the liver 'dirty') it is not safe to use comfrey internally.
The liver must be cleaned up, along with the bowels. It is important to keep the bowels cleaned out so the waste from the liver has someplace to go (out the bowels instead of backing up in the body).