Drug and Medication Side Effects

Along with its intended results, a drug may cause a number of unwanted side effects. These effects can happen when you start a new medication, decrease or increase the dose of a medication, or when you stop using a medication.

Doctor talking with older patient
Blend Images - REB Images / Brand X Pictures / Getty Images 

A side effect that occurs in one percent or more of people taking a specific medication is considered by medical researchers to be caused by that medication. Examples of common drug side effects include nausea, vomiting, fatigue, dizziness, dry mouth, headache, itching, and muscle aches and pains.

Some side effects may be severe and require medical attention, while others may be mild and of little concern. Severe or annoying side effects are one of the main reasons why people stop taking their medications.

If you are having worrisome side effects, your doctor may want to change your dose, try a different medication in the same drug class, or recommend some type of dietary or lifestyle change.

Do All Medications Have Side Effects?

All medications used for treating any type of health condition can cause side effects. However, many people who take a drug or combine drugs have no side effects or minor side effects.

Your likelihood of having side effects from your medications may be related to your age, weight, sex, and overall health. Additionally, ethnicity and race or the severity of your disease may increase the possibility of side effects. These factors may determine if you experience side effects from your medications, the severity of your side effects, and their duration.

Calling the Doctor About a Side Effect

It is important for you to be familiar with the potential side effects of your medications and what you should do if you have signs of them. Also, it is essential that you let your doctor know if you are having side effects. Although many side effects are minor and not harmful, they can be a sign of danger or an indication that your drug is not working properly.

Call your doctor if you notice any of these side effects:

  • Abdominal pain
  • Blurred vision
  • Constipation
  • Diarrhea
  • Dizziness
  • Headaches
  • Loss of appetite
  • Memory loss
  • Palpitations
  • Problems with coordination
  • Ringing in the ears
  • Skin rashes or hives
  • Swelling of hands or feet
  • Syncope (loss of consciousness or fainting)

If any side effects worry you, always call your healthcare provider!

Since some side effects may not make you feel ill, your doctor may want you to have regular laboratory tests to detect any problems early. For example, if you are taking a statin drug for high cholesterol, such as Lipitor (Atorvastatin), your doctor most likely will recommend that you have a liver function test before you start the drug, 12 weeks after you start therapy, and periodically thereafter.

Should I Stop Taking My Medication If I Have a Side Effect?

Do not stop taking your medications without talking to your physician first. If you think you are having a serious side effect that is of immediate danger to your health, call 911 or go to your local emergency room.

All drugs have benefits and risks. The risk is the chance of a serious side effect from your medication. These risks can be less serious, such as a mild stomach ache. They can interfere with the quality of your life, such as causing sexual problems. Or, they are potentially life-threatening, such as liver damage. With guidance from your health care provider, you will need to balance the risks and benefits of any treatment.

What Should I Ask My Doctor and Pharmacist About Drug Side Effects?

  • What are the possible side effects of this drug?
  • Which side effects am I most likely to have?
  • How soon will the side effects start?
  • How long will the side effects last?
  • Will the side effects go away by themselves?
  • Can I do anything to prevent the side effects?
  • Do I need to have any tests to monitor for side effects?
  • Are there any dangerous side effects I should know about?
  • What should I do if I have a side effect?
  • If I have a side effect, are there other drugs I can take?

Finding Information About My Drug’s Side Effects

Your local pharmacy: When you have a prescription filled, your pharmacist should give you a printout that provides you with information about your drug, including possible side effects. If your medication has specific warnings about potentially dangerous side effects, your pharmacist must give you a medication guide required by the U.S. Food and Drug Administration (FDA) to assure that you are aware of any known serious side effects.

If you are not given a drug fact sheet or a medication guide, ask your pharmacist. And, if you have any questions about your medications, ask the expert, your pharmacist!

The National Institutes of Health provide DailyMed. This drug guide has in-depth information on several thousand prescription and over-the-counter medications. Each drug profile in the guide includes facts about side effects that you should report to your healthcare provider as soon as possible as well as side effects that usually do not require medical attention.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. Food and Drug Administration. Finding and learning about side effects (adverse reactions). Updated July 19, 2018.

  2. Smith Marsh DE. Severity of adverse drug reactions. Merck Manual. Updated September 2018.

  3. National Institute on Aging. Safe use of medication for older adults. Updated June 26, 2019.