Drug Allergy
What is it?
A drug allergy occurs when you have a physical reaction
to a certain drug that you have taken.
Who gets it?
Anyone can develop a drug allergy. You can become
allergic to medications that you have taken with no
reaction in the past. People with a family history of drug
allergies are more likely to have drug allergies.
What causes it?
An allergic reaction occurs when the immune system
produces antibodies and other disease fighting cells in
response to an allergen, in this case a specific drug. The
antibodies release chemicals that actually injure the
surrounding cells and cause the physical symptoms of an
allergic reaction. Certain antibodies release histamines,
which affect the skin, mucous membrane, mucous gland, and
smooth muscle cells. Life-threatening allergic reactions
can occur without any previous symptoms of allergy. Drugs
in the penicillin family are a common cause of drug
allergies.
What are the symptoms?
Most drug allergies cause symptoms such as itching,
skin rash, and hives, which occur soon after taking
the drug. However, people with severe drug allergies can
experience a dangerous condition called anaphylaxis.
Symptoms include sudden anxiety and weakness, difficulty
breathing, tightness in the chest, very low blood
pressure, loss of consciousness, and shock. Anaphylactic
shock can occur within minutes and result in death. A
patient in anaphylactic shock needs immediate medical
treatment. Some children develop a rash called a toxic
rash when taking ampicillin or amoxicillin. This rash
looks like small pink spots on the back, chest, and
abdomen. This type of rash is not an allergic reaction to
the drug.
How is it diagnosed?
There are few diagnostic tests for drug allergies. Drug
allergies are diagnosed according to the types of symptoms
that occur while a drug is being taken. A definite
diagnosis can usually be made if symptoms stop when the
drug is stopped.
What is the treatment?
If you think you have had a reaction to a medication,
you should contact your doctor. He or she will tell you
whether to stop taking the drug. Usually, the reaction
stops when the medication is out of your system. If your
symptoms include itching or swelling, your doctor may give
you medication to help with these symptoms. Anaphylactic
shock is treated with an injection of epinephrine, a
hormone that stimulates the heart and relaxes the airways.
Self-care tips
If you have known drug allergies, make sure you wear a
Medic-Alert bracelet so medical personnel are aware of
your condition in case you need emergency treatment. Make
sure your doctors and pharmacist are aware of your drug
allergies. Keep in mind that people who are allergic to a
certain drug, such as penicillin, will be allergic to all
drugs in that family.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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