Skip to Content


Reminder: It is important to take medications as prescribed. Consult your doctor before abruptly stopping your medications. Make sure to record any side effects or reactions you may be experiencing.


It is also important to be honest with your provider and make sure they are aware of any over the counter medications, medications prescribed from another provider, herbs, supplements, or other drugs you may be taking.

  1. Adverse Drug Reaction vs. Side Effect
  2. When to call your provider
  3. When to go to the Emergency Room

Adverse Drug Reaction (ADR) vs. Side Effect

What is an adverse drug reaction (ADR)?

  • An adverse drug reaction is an unexpected and unintended response to a medication that is different from its original use. This reaction directly causes harm at normal medication doses, and during normal medication use.
  • For example: An allergic reaction to Penicillin (antibiotic) may cause itching, swelling of the face and throat, difficulty breathing, or difficulty swallowing. This reaction is outside of what we would normally expect for the medication to cause. This is considered an adverse reaction.

What is a medication side effect?

  • A side effect is an expected and known secondary effect of a medication. The side effect is typically not the primary reason the drug was chosen but can occur in addition to the therapeutic effect of the medication.
  • For example: Penicillin (antibiotic) can be prescribed for an infection. A side effect to this medication might be mild diarrhea. Although, the medication is prescribed primarily to get rid of the infection, some expected side effects may occur that were not intended.


  • Keeping a log of your medication side effects.
    • Be sure to include:
      • Date
      • Time you took your medication
      • Time you are experiencing the side effect
      • Describe the side effect you are experiencing.

When to call your provider

  • If you’re experiencing:
    • Unusual changes in behavior or mood
    • Difficulty thinking or remembering
    • Hives
    • Rash
    • Nausea
    • Vomiting
    • Headache
    • Loss of appetite
    • Constipation
    • Changes in blood glucose levels up to 450

When to go to the emergency room

  • If you are experiencing an allergic reaction such as swelling of the face, lips, tongue, throat, difficulty breathing, or difficulty swallowing
  • If you’re pregnant and have vaginal bleeding or pelvic/abdominal pain
  • If you are experiencing:
    • Shortness of breath
    • Chest pain
    • Fainting
    • Blurred vision
    • Palpitations
    • Abdominal pain
    • Seizures
    • Change in mental status (confusion, hallucinations)
    • Uncontrollable bleeding
    • Thoughts of suicide or harming yourself
    • Significant changes in blood pressure with symptoms such as light headedness, dizziness, headache, blurred vision, chest pain, fatigue, confusion
    • Change in blood glucose level > 450 or < 50 and unable to stabilize blood sugar

If you experience other strange symptoms or anything out of the ordinary for you, consider it an emergency, and seek immediate medical attention.


Carolyn A. Bernstein, M. D. (2018, April 23). How to talk to your doctor about medication. Harvard Health. Retrieved November 23, 2021, from….

Parker, C. (2012, February 20). Talking to your doctor about drug side effects. Retrieved November 23, 2021, from….

Rehan, H. S., Chopra, D., & Kakkar, A. K. (2008, June 13). Physician's Guide to Pharmacovigilance: Terminology and Causality Assessment. European Journal of Internal Medicine. Retrieved November 23, 2021, from

Riedl, M. A., & Casillas, A. M. (2003, November 1). Adverse drug reactions: Types and treatment options. American Family Physician. Retrieved November 23, 2021, from

VHA Pharmacy Benefits Management Strategic Healthcare Group and the Medical Advisory Panel, VHA Pharmacy Benefits Management Strategic Healthcare Group, & Medical Advisory Panel. (2006, November). Adverse drug events, adverse drug reactions. U.S. Department of Veteran Affairs Pharmacy Benefits Management Services. Retrieved November 23, 2021, from….