Drug Allergies and senior health

Some people have allergic reactions to certain medicines. When a drug enters the body, the immune system can mistakenly treat it as a threat and create antibodies (called IgE antibodies) against it. If you take the drug again, these antibodies trigger the release of histamine, which the body uses to try to expel the drug.

• Symptoms of drug allergies
• Common drugs that cause allergies
• Diagnosing drug allergies
• Treatment options
• Talking with your doctor

Symptoms of drug allergies

Allergic reactions can range from mild to severe. Many drugs cause minor side effects like an upset stomach, but a true allergic reaction triggers histamine release, which can cause hives, rash, itching, congestion, and swelling in the mouth or throat.

Severe reactions may include difficulty breathing, bluish skin, dizziness, fainting, confusion, rapid heartbeat, nausea, diarrhea, and abdominal pain.

Common drugs that cause allergies

Penicillin is the most common drug allergy. Other antibiotics in the penicillin family can also trigger reactions. Sulfa drugs, barbiturates, anticonvulsants, insulin, local anesthetics like lidocaine, and iodine (found in some X-ray contrast dyes) are also frequent culprits.

Diagnosing drug allergies

Your doctor diagnoses a drug allergy by reviewing your medical history and symptoms. For penicillin allergies, a skin test can confirm the diagnosis. However, skin tests don't work for all drugs and can be risky for some.

If you've had a severe, life-threatening reaction to a drug, your doctor will simply avoid prescribing it. Testing whether the initial reaction was a "true" allergy isn't worth the risk.

Treatment options

Treatment focuses on relieving symptoms. Rash, hives, and itching usually respond to antihistamines, sometimes with corticosteroids added. Bronchodilators can help with coughing and lung congestion by opening the airways. For severe anaphylactic reactions—difficulty breathing or loss of consciousness—epinephrine (adrenaline) is injected or inhaled immediately.

Desensitization is sometimes used for penicillin allergy. This involves injecting tiny amounts of penicillin in gradually increasing doses so your immune system learns to tolerate it.

If you're allergic to certain antibiotics, your doctor can prescribe alternatives.

Talking with your doctor

Always tell your healthcare provider about drug allergies before any treatment, including dental work. Wear a MedicAlert bracelet or carry an allergy card. In an emergency, this information could be lifesaving.