Drug Allergies - Topic Overview
What is a drug allergy?
A drug allergy happens
when you have a harmful reaction to a medicine you use. Your body's
immune system fights back by setting off an
allergic reaction. Most drug allergies are mild, and
the symptoms go away within a few days after you stop using the medicine. But
some drug allergies can be very serious.
Some drug allergies go
away with time. But after you have an allergic reaction to a drug, you will
probably always be allergic to that drug. You can also be allergic to other
drugs that are like it.
A drug allergy is one type of harmful, or
adverse, drug reaction. There are other kinds of adverse drug reactions. Symptoms and treatments of different kinds of adverse
reactions vary. So your doctor will want to find out if you have a true drug
allergy or if you have another type of bad reaction that isn't as
What are the symptoms?
The symptoms of a drug
allergy can range from mild to very serious. Most of the time they appear within 1 to 72 hours. They include:
- Hives or welts,
a rash or blisters. These are the most common symptoms of drug
allergies. See a picture of
skin reactions caused by drug allergies .
- Coughing, wheezing, a
runny nose, and trouble breathing.
- A fever.
skin conditions that makes your skin blister and peel. These include
toxic epidermal necrolysis and Stevens-Johnson Syndrome.
- Anaphylaxis, which is the most
dangerous reaction. It can be deadly, and you will need emergency treatment.
Symptoms include hives all over your body, trouble breathing, swelling of the throat or mouth, and/or feeling very lightheaded. These usually appear within 1 hour
after you take the medicine. Without emergency care, you could die.
What medicines commonly cause an allergic reaction?
Any medicine can cause an allergic reaction. A few of the most common
If you are allergic to one medicine, you may be allergic
to others like it. For example, if you are allergic to penicillin, there is a chance that you may also
be allergic to similar medicines, such as amoxicillin.