The contraindicators can be anything from a rash or headache, to death. The list is usually quite long with all medicines. This is the stuff that can happen that we do not want to happen. Some side effects are rare, some are common. Some are very mild and just a mere nuisance, some can put you in the ground.
Medicines can be VERY dangerous.
There is risk in all cures. Especially the farther one moves away from what is naturally in the earth. To illustrate what I mean, drugs and their side effects are listed below from THE PILL BOOK and The U.S. Pharmacopoeia. According to surveys of chain drug stores, mail order, and drug wholesalers, these are the 10 most prescribed drugs in America. Each of the medicines are listed with their most common classification or use followed by the side effects.