What is Drug Allergy?

A drug allergy is an adverse reaction of the body’s immune system to a specific drug. Most people confuse it with Drug Reaction. However, drug reaction occurs when there is a reaction in between two drugs inside a human body and is related to the drug’s mode of action. But drug allergy is caused by the action of certain drugs on body.

Less than ten percent of drug reactions are allergic in nature. If you suffer from a known drug allergy, always inform the health care provider before you undergo any medical treatment. To avoid complications, wear a medical alert tag or carry the information about the drug allergy in your wallet. The following article explains drug allergy in detail.

Causes of drug allergy

A drug allergy develops when the immune system takes the drug to be harmful substance instead of a helpful remedy. The immune system then comes into action by releasing chemicals which causes allergic signs and symptoms.

Till date, it is not clear why only few develop drug allergies where as rest don’t. There may be inherited traits, environmental factors or the medications taken overtime which can be the causes for drug allergies.

  • Antibiotics – Penicillin, related antibiotics and antibiotics containing sulfonamides can cause drug allergies. These antibiotics even cause non-allergic reactions like diarrhea and nausea.
  • Vaccines – In rare cases, drug allergies develop after vaccination. Vaccine itself or even the ingredients in it like neomycin or egg can cause allergic reactions.
Symptoms of drug allergy

A drug allergy can be mild, moderate or severe. It may occur days or weeks after exposure to the drug and is fatal only in rare cases. A mild allergy causes rash, itching and localized hives. You may become sensitive to light and develop red, raised patches on the skin. A moderate allergy can cause swelling in the face, fall in blood pressure, breathlessness and erratic heartbeat. A severe allergy manifests itself in the form of anaphylaxis where the patient starts choking and the blood pressure falls rapidly. Anaphylaxis occurs within an hour of taking the drug.

A mild adverse drug reaction on the other hand results in vomiting, diarrhea, headache, insomnia or fatigue. A moderate drug reaction can cause excessive bleeding, puzzlement, and damage to the vital organs like kidney and liver and muscle wastage. Some people may be allergic to aspirin and NSAIDS and this causes an asthma attack, similar to an IgE induced allergic reaction.

Diagnosis of Drug Allergy

The physician diagnoses the allergy by examining the history of the medicinal use and by performing allergy testing. Allergy to penicillin can be detected by undergoing a skin test, while detecting other drug allergies may require a blood test. Once the allergy is diagnosed, you can go further with the treatment.

Treatment for Drug Allergy

The first thing to do when treating a drug allergy is to find out whether the allergic reaction is serious or mild. The most important step is to identify the drug causing the allergy and to avoid taking it in future.

  • For a mild allergy, you need to stop taking the drug immediately and take anti-histamine to stop the itching and rash. You can even use home remedies such as using cold compress on hives or taking anticongestants to treat stuffy nose.
  • Moderate allergy requires administration of corticosteroids, while the person needs an epinephrine injection in case of an anaphylaxis.
  • In case of a severe allergy, you must immediately rush to the emergency department of a hospital.

Desensitization therapy is another treatment method. Here, small doses of a particular drug are administered and gradually the dose amount is increased till the person develops resistance to that drug.

This is all about drug allergy which may be helpful to you.