Information about side effects can be obtained by asking your physician or pharmacist or consulting a reliable reference. Some drugs need be taken only until symptoms stop, while others should be taken for a period specified in advance. For example, pain relievers can be stopped when your pain goes away, but antibiotics are typically prescribed for 7 to 14 days to eradicate germs that remain even though symptoms of the infection have disappeared. In some cases it will be advisable to make up the dose to maintain an adequate blood level of a medication. In other cases it will not matter, and doubling the dose will increase the likelihood of side effects.
Some doctors provide instruction sheets on common prescription drugs.
A package insert may be available from the pharmacist who fills the prescription, but these tend to be overly technical. Excellent reference books are available, and comprehensive information will soon be available on the Web sites of online pharmacies. Generic drugs usually cost less and are just as potent as name brands. Some doctors routinely prescribe them, but others either think they are inferior or simply do not bother. With a few medicines for serious diseases there may be a medical reason to avoid a generic drug.