Drugs Used for Off-Label Purposes

Doctors can prescribe drugs for other than the use they were approved for by the FDA. It seems to be up to each physician how they prescribe these and are often encouraged by drug reps/companies to do so (larger profits). Most, if not all, drugs come with side effects and it's wise to look into these and discuss them with your doctor.
The FDA approves drugs which they feel can do more good than harm but based on clinical trials for the use they were concocted for.

Look carefully to see if the drugs you are taking are off-label (being used to treat something other than it was intended for) You can check your drugs here.

You can also check to see if your doctor or teaching hospital has received money or something of value from a drug company here and may be inclined to offer drugs that they are rewarded for prescribing.

Always ask your doctor what the prescription is for, what are the side effects, is it FDA approved for the diagnosis and are there alternatives.