People react to medications differently and all medications have the potential to cause an adverse reaction. Most people will have an adverse reaction at some point in their lives.
Allergic reactions
A drug allergy results when the immune system over-reacts to a particular medicine. Many different drugs, including those over the counter or different herbal supplements, can cause an allergic reaction. The most common symptoms are hives, rash or fever. Drug allergies can also cause difficulty breathing and problems with the liver, kidneys, muscles and joints or blood counts.
Allergic reactions can be more common if you:
- Previously had a reaction to the same or similar drug.
- Have a medical condition that weakens the immune system such as EBV or HIV.
- Have other allergies.
Non-allergic reactions
Most drug reactions though are not true allergic reactions. They are often due to unwanted side effects and can be more common if the dose is incorrect or if it interacts poorly with another medicine. Allergic and non-allergic reactions can sometimes look very similar. If severe, any adverse reaction can be life-threatening and should be discussed with your doctor.
Non-allergic reactions can be more common if you:
- Are taking many medicines.
- Have inherited traits that increase susceptibility to certain toxic effects of drugs.
- Have a medical condition that effects the ability to absorb or process drugs.
Common allergic and non-allergic reactions
- Penicillin and sulfa antibiotics. Can cause hives or other rash. Severe reactions can cause difficulty breathing or drop in blood pressure.
- Aspirin and other over the counter pain medicines. Can cause hives or difficulty breathing.
- ACE inhibitors (a type of blood pressure medicine). Can cause severe face, tongue and/or throat swelling.
- X-ray contrast. Can cause hives, difficulty breathing or drop in blood pressure.
What do you do if you suspect an adverse drug reaction?
- Let your doctor know right away if you think you are having an adverse reaction.
- Write down all your medications and how long you’ve been taking them.
- Write down when your symptoms began and how long they lasted.
- If possible, bring your medications to your doctor’s visit.
- Don’t forget to include any over-the-counter medicines, herbal supplements, vitamins and alternative therapies.
Call 911 if you are having an adverse drug reaction which is causing problems with your breathing or blood pressure. These reactions can be life-threatening.
When to see an allergist
If you think you have had a severe allergic reaction to a medicine, are allergic to a medicine that you need or are having reactions to multiple medicines, you should see an allergist. You can find out what medicines you really need to avoid. If you need to take a medicine to which you are allergic, your allergist may be able to help you take it in a safe way.
