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Allergies to medications

Many medications can cause adverse side effects, and certain medications can trigger allergic reactions. In an allergic reaction the immune system mistakenly responds to a medication by creating an immune response against it. The immune system recognises the medication as a harmful substance and the body produces certain chemicals such as large amounts of histamine in an attempt to expel the medication from the body.

What are the symptoms of a medication allergy?

Symptoms can range from mild to life-threatening. Even in people who aren't allergic, many medications can cause irritation such as an upset stomach. But during an allergic reaction the release of histamine can cause symptoms like hives, skin rash, itchy skin or eyes, congestion and swelling in the mouth and throat.

A more severe reaction may include difficulty breathing, blueness of the skin, dizziness, fainting, anxiety, confusion, rapid pulse, nausea, diarrhoea and abdominal problems.

Which medications most often cause an allergic reaction?

The most common medication associated with allergies is penicillin. Other antibiotics similar to penicillin can also trigger allergic reactions.

Other medications commonly found to cause reactions include sulfa medications, barbiturates, anticonvulsants, insulin and iodine (found in many X-ray contrast dyes).

How are medication allergies diagnosed?

A doctor diagnoses a medication allergy by carefully reviewing your medical history and symptoms. If your doctor suspects that you are allergic to an antibiotic such as penicillin, he or she may do a skin test to confirm it. However skin testing does not work for all medications, and in some cases it could be dangerous. If you have had a severe, life-threatening reaction to a particular medication, your doctor will simply rule out that medication as a treatment option for you. Conducting an allergy test to determine if the initial reaction was a 'true' allergic response isn't worth the risk.

How are medication allergies treated?

The primary goal when treating medication allergies is symptom relief. Symptoms such as rash, hives and itching can often be controlled with antihistamines, and occasionally corticosteroids.

For coughing and lung congestion medications called bronchodilators may be prescribed to widen the airways. For more serious anaphylactic symptoms - life-threatening reactions including difficulty breathing or loss of consciousness - adrenaline (or epinephrine) may be given.

If you are severely allergic to certain antibiotics, there are alternative antibiotics your doctor can prescribe.

How can I be prepared?

If you have a medication allergy, you should always inform a doctor before undergoing any type of treatment, as well as your dentist. It is also a good idea to wear a MedicAlert bracelet or pendant, or carry a card that identifies your medication allergy. In cases of emergency it can save your life.

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WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on December 07, 2016

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