Drug Allergy
What is Drug Allergy?
A drug allergy occurs when the immune system mistakenly identifies a medication as harmful, leading to an allergic reaction. This response can vary in severity and may cause a range of symptoms. It’s important to note that a drug allergy is different from a drug intolerance, which typically involves non-immune-related side effects. In cases of true drug allergies, the immune system generates an inappropriate response, which can sometimes be life-threatening. Drug allergies can develop at any age, even after many previous doses of the same medication without issues. Understanding this condition is crucial for preventing future allergic reactions and ensuring effective treatment.
What causes a drug allergy?
A drug allergy is essentially an immune system error where your body mistakenly identifies a medication as a harmful foreign invader, like a virus or bacteria. This usually happens after an initial “sensitization” exposure, during which your immune system produces specific antibodies (often IgE) or sensitizes T cells against the drug. Upon subsequent exposure to the same drug, these immune components rapidly react, releasing chemicals like histamine that cause the various allergy symptoms, ranging from mild skin rashes and itching to severe, life-threatening anaphylaxis. Many drugs are small molecules that become “haptens” by binding to larger body proteins, forming a complex that the immune system then recognizes as foreign, or they act as “prohaptens” that are metabolized into reactive forms before binding to proteins. In some cases, drugs can also directly interact with immune receptors, leading to an allergic response without prior sensitization.
Which medications cause allergies?
Many medications can cause an allergy, but the most common include:
- Penicillin and other similar antibiotics
- Nonsteroidal anti-inflammatory drugs (ibuprofen, aspirin, naproxen)
- Anti-seizure drugs
- ACE inhibitors
- Monoclonal antibodies
- Chemotherapy medicines
If you have an allergy to one drug, you have a higher risk of being allergic to other medications.
What symptoms develop due to a drug allergy?
Since medications enter your bloodstream and travel throughout your body, they cause a range of allergy symptoms, such as:
- Sneezing
- Cough
- Hives
- Angioedema
- Skin rash
- Runny or congested nose
- Itchy, watery eyes
- Nausea and vomiting
- Diarrhea
- Headaches
Of all the symptoms, the most common is a skin rash.
How do specialists diagnose drug allergies?
A skin prick or intradermal skin test can accurately diagnose a few types of drugs. In many cases, your provider at Bellagio Family Medical, identifies drug allergies, including penicillin and other antibiotics, with a graded challenge test. During a challenge test, your provider gives you doses of the drug suspected of causing your allergic reaction while observing you for potential responses. The test begins with one tiny amount. If you don’t have an allergic reaction, you get another slightly higher dose. Your provider repeats this process until you reach the standard therapeutic dose. If you get to the therapeutic dose without reacting, you’re not allergic to that drug.
What if I have an allergy to a drug I need to take?
Penicillin and aspirin are two of the top drug allergies, and they’re medications people often need to keep taking for health reasons. A process called desensitization may give you the ability to keep taking your medication.
Desensitization involves taking frequent, small doses of the drug, increasing the amount each time. If you have any allergic reaction, your provider treats the symptoms and then continues the desensitization process. By the time you reach a therapeutic dose, you should be desensitized and can take the medication.
If you have an allergic reaction after taking medication, don’t wait to schedule an appointment at Bellagio Family Medical. Call or book online today to get a thorough check-up and expert care.
