(FORTUNE Magazine) – A bewildering choice confronts anyone with a garden variety pain like a headache, a stomachache, or a sprained ankle. Are you better off taking aspirin, Motrin IB, Advil, Nuprin, Tylenol, or one of the more than 50 other colorfully packaged mild analgesics that decorate drugstore shelves like so many bright flowers? Answer: It depends on the type of pain and on which drugs work best for you. In some ways those medications differ from one another about as much as Japanese compact cars do. But there are subtle differences, so their effectiveness varies from one person to another. All the drugs mentioned except Tylenol (generic name: acetominophen) fall into the nonsteroidal anti- inflammatory category, which means that they work not only against pain but also against swelling -- in arthritis, for example. (Tylenol is a mild painkiller but does not act against inflammation.) ''If you sprain an ankle, it doesn't matter what you take,'' says Gary J. Bennett, a neurophysiologist and pain researcher at the National Institutes of Health. ''But if you have arthritis, it does matter, because chronic intake of aspirin could give you ulcers. So take something that's coated or buffered to reduce the acidity of aspirin.'' For tension headaches, aspirinlike drugs work fine. There's good news for the 11 million migraine sufferers in the U.S.: The FDA has finally approved Glaxo's Imitrex, which has been used successfully in 25 countries since 1991. The widely praised drug selectively constricts blood vessels in the brain and helps more than 70% of patients within an hour -- something no other antimigraine medication has achieved. If pain continues more than a week or so, you should consult your doctor. If he can't help, consider a private pain control clinic manned by a range of specialists. Such clinics treat people with ailments ranging from chronic headaches to backaches -- often with great success. Says Kenneth E. Shandell, a neurologist who runs the Pain Treatment Centers in San Diego: ''The key is prompt evaluation and effective analysis of a person's condition. When you identify the problem and treat it, the symptoms go away. Given the sophisticated options now available, almost no one has to live with intractable pain anymore.''