From the homely aspirin to the most sophisticated prescription medicine on the market, all drugs come with side effects. Many are minor, some are just an inconvenience, a few are serious, and some are just plain strange.

Perhaps the most common set of side effects for drugs that work inside your body involves the gastrointestinal system. Nearly any drug can cause nausea or an upset stomach, though it may only happen to a handful of people. For drugs used on the outside, skin irritation is a common complaint.

An allergic reaction could happen with any drug. That can range from itching and rash all the way to a life-threatening anaphylactic reaction.

Some drugs can’t help but trigger side effects because of their chemical structure. The common allergy drug diphenhydramine (also known by the brand name Benadryl) is one. Though it eases allergy symptoms, it also blocks the chemical acetylcholine, and that leads to drowsiness and a host of other side effects, including dry mouth.

Some drugs have barely noticeable side effects at the right dose. Typically, warfarin (Coumadin, Jantoven), used to prevent blood clots, usually works well and isn't bothersome, but serious internal bleeding can happen in the wrong situation.

Still, sometimes testing doesn't reveal everything about a drug’s side effects, and they don't show up until after the medication enters the marketplace and more people start using it. That’s where MedWatch comes in. The FDA’s post-marketing surveillance program seeks voluntary input, mainly from health care professionals, on unwanted effects they see in ''the real world.'' Sometimes these reports are numerous or serious enough for the FDA to take regulatory action, such as adding warnings to a drug’s label.

This happened with the psoriasis drug Raptiva. The FDA required that the drug carry the agency's strongest warning, known as a black box warning, after it received reports of brain infections and meningitis in patients taking the drug. The drug was later taken off the market.

Drug companies are also required to report adverse events to the FDA. Failure to do so can lead to prosecution. In 1985, employees of two drug companies were fined or sentenced to community service for not reporting adverse events involving the blood pressure drug Selacryn and arthritis drug Oraflex. Both products were pulled from the market.

Media Contact: 
Allison Grey 
Journal Manager 
Journal of Clinical chemistry and Laboratory Medicine
Email: jcclm@molecularbiol.com