Skip to content
My WebMD Sign In, Sign Up

Information and Resources

Drug Side Effects Explained

From the homely aspirin to the most sophisticated prescription drug 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 taken internally involves the gastrointestinal system. Nearly any drug can cause nausea or an upset stomach, though it may only happen to a handful of users. For drugs used externally, skin irritation is a common complaint.

Drug Side Effects: Types

Side effects fall into several categories:

Allergic reactions can happen with any drug and can range from itching and rash all the way up to a life-threatening anaphylactic reaction.

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

Some drugs have barely noticeable side effects when dosed properly. For example, Warfarin (Coumadin, Jantoven), used to prevent blood clots, is usually well tolerated, but serious internal bleeding can occur.

Side effects may only pop up when certain drugs are mixed with certain other things. These might also be considered drug interactions. Drinking alcohol with narcotic painkillers has caused an alarming increase in accidental overdose deaths. Drinking grapefruit juice can affect the blood levels of several drugs, including the heart drug Digoxin.

To find more about a drug's side effects, information about them is available on the label of over-the-counter drug products and on package inserts or printed materials dispensed with prescription drugs. Because the inserts include such a long list of possible bad effects, it is very helpful to also talk to your pharmacist or doctor if you have any questions regarding a drug's side effects.

 

Drug Side Effects: The FDA's Role

Before a drug can come on the market it must be approved by the FDA. The New Drug Applications (NDAs) submitted by pharmaceutical companies contain, first and foremost, clinical evidence that the drug has the therapeutic effect it’s supposed to have and is safe. This proof comes from testing of the drug, first in animals and then in humans. Once the basic questions of safety and efficacy are settled, the FDA will approve the drug if it deems that its benefits outweigh its risks.

Still, sometimes not everything is known about a drug’s side effects until after it 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 adverse effects they may be seeing in ''the real world.'' Sometimes these reports are numerous and/or serious enough for the FDA to take regulatory action, such as adding warnings to a drug’s label. One example of that involves 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.

WebMD Medical Reference

Hot Topics

Health Solutions From Our Sponsors

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

hands on abdomen
Can you catch one?
Woman sitting in front of UV lights
Is yours working?
woman using breath spray
What's causing yours?
womans hand on abdomen
Are you ready for baby?
MS Overview
Recognizing symptoms.
bowl of yogurt with heart shape
Eat for a healthy heart.
woman doing pushups
To help you get fit.
Colored x-ray of tooth decay
Know what to look for.
Woman sitting with child
Do you know the symptoms?
mosquito
Stings, bites, burns, and more.
Allentown, PA
Are you living in one?
Thyroid exam
See how much you know.

Women's Health Newsletter

Find out what women really need.