Medication Allergies

An allergy to medication occurs when the body considers the medication as an allergen (invader) and an immunological response occurs to fight it off. It can also be referred to as a “medication hypersensitivity”. The degree of severity can vary significantly for any given individual.

Common medication allergy symptoms are an itchy skin or rash, hives, swelling, trouble breathing due to swollen airways and/or bronchospasm (spasm narrowing the airways), a drop in blood pressure and fainting.

Medication allergies can be divided into immediate and delayed reactions, according to the World Allergy Organisation (WAO). An immediate reaction occurs typically within an hour following the administration of the medication. There can be a slight delay in the start of the symptoms if the medication is taken per mouth with food, slowing the absorption. If medication is given via infusion, the reaction can occur within seconds. The symptoms’ severity can increase if the medication is continued (for instance when someone is receiving the medication via an infusion) and it can result in a life-threatening reaction, called anaphylaxis. It can happen even though in the past, no symptoms were experienced with the same medication.

A delayed reaction presents a few days after initiating new medication and presents as a skin rash that may or may not be itchy. The skin rash usually involves most of the skin (trunk, back and extremities). This delayed reaction is typically not serious. In very rare cases a skin reaction due to a medication allergy can result in Stevens-Johnson syndrome, a life-threatening condition that needs urgent medical attention and will present with a rash and other systemic symptom. In case of a delayed reaction, a “medication challenge test” can be considered where a small dose of the medication is given and assessed for a repeat reaction, this is usually recommended for medication where alternatives are scarce.

An acute/immediate reaction might result in hospitalisation. The first important step is to stop administering the medication causing the reaction. Call an ambulance if the person has difficulty in breathing, is feeling severely lightheaded, faints or has swelling of their face, lips, and throat. The person will be treated in the ambulance on their way to hospital with oxygen, adrenaline, antihistamines, cortisone, and medication to relax the airway (bronchi). Intravenous fluids will assist to increase the blood pressure if low, and to give easy access to medication administering to treat severe symptoms. If the medication causing the allergy is crucial, an allergy skin test can be performed to determine whether the patient is indeed allergic to the active pharmaceutical ingredient and which alternatives will be safe for the individual in future.

Several risk factors were identified for developing a medication allergy: the female gender, previous medication allergies, recurrent exposure to medications, genes, and diseases like HIV and leukemia. Neuromuscular blocking agents used in anesthesia, cause more immediate reactions in females than in men and a certain antibiotic, Gemifloxacin, elicited an allergy in 30% of women versus only 3% in men in the same age population, the reason for this difference is not well-defined. In diseases like HIV and leukemia, the person has abnormal immune response, the former due to an inflammatory milieu enhancing allergies and the latter due to abnormal lymphocytes.

If your allergy is confirmed, be sure to know that you might also have a sensitivity to other medication in the same class, therefore, it is good to know all the possible brand names with the active ingredient that you are sensitive to as you might be at risk of being allergic to those too. In some cases, people will have an allergic reaction to the inactive ingredients (excipients) in the medication, that means that the active ingredient is not the culprit but something else added to it to form the tablet/capsule. In such cases, one brand name might then not elicit an allergic reaction, but another might. It is advisable to wear a bracelet with your allergy information and to inform your loved ones which medications are a problem.

Article: Dr. Janet Strauss is the Chief Operations Officer at Medwell SA – The Home Health Care Specialists.
For more information visit www.medwell.co.za