Medication Allergy

Introduction

Medications can sometimes cause a variety of adverse reactions. Some of these could simply be known side effects, while others may be allergy. Medication allergies occur to a wide variety of medications including antibiotics (e,g. penicillin), aspirin/NSAIDS, radiocontrast media, antiepileptic drugs, anesthesia medications, anticancer drugs such as platins and taxanes, and biologic medications. Medication allergies can be very serious and even life-threatening. They may also limit treatment options, often necessitating the use of a medication with more side effects and less effectiveness. Recent studies show that most children who have a history of penicillin/amoxicillin allergy with only a skin rash are likely not allergic and can tolerate penicillin and related medications such as amoxicillin in the future.

Symptoms

Symptoms of medication allergy include hives, swelling, wheezing, throat closing, and shock (low blood pressure). The symptoms may occur early, immediately after administration, or hours to days later, depending on the medication and its route of administration. Occasionally, drug allergies can cause dysfunction of internal organs (e.g. liver damage with elevated liver enzymes), as well as extensive skin damage.

Diagnosis and management

Diagnosis and management of drug allergies is very challenging. Diagnostic skin tests from manufacturers are only available for penicillin. Skin tests, as well as blood allergy tests, are often not accurate. Sometimes reactions occur by non-allergic mechanisms, making allergy testing unhelpful (e.g. aspirin, ibuprofen, X-ray dye). In-office drug challenges remain the gold standard diagnostic tool to help confirm or rule out a drug allergy. Management includes avoidance, use of alternative agents, testing (often with samples of the medication that you have brought into the office), and rarely drug desensitization within the hospital. Patients may also benefit from obtaining a medic alert bracelet describing the allergies.