For example, many people are allergic to penicillin and may die if administered this drug. Physicians prescribe medicines for particular people and very specific problems. If the person is seeing more than one physician for medicines, the physicians should be in contact with each other, because medicines may interact in ways that are harmful. Many pharmacists offer advice and cautions about drug interactions for their clients. Nature of Drug Effects Drugs are powerful and at times, unpredictable.
Some drugs slow people down and some speed people up.
A drug that affected someone one way last year may affect her or him differently this year. Effects of any drug depend on people s age, weight, gender, medical history, and the setting where the drug is used. Sometimes people take two or more drugs at the same time. The effects of this may be an unexpected tripling or quadrupling of the power of the drugs involved. People take drugs to feel better, to feel different, to help them cope, to socialize, etc.