Drug allergies are a type of adverse drug reaction, but only around 5-10 percent of drug reactions are true drug allergies. Your immune system overreacts to a medication (or its breakdown products) and this reaction generates your symptoms. Drug allergies may happen with over-the-counter or prescription medications you take, and even your herbal supplements may be culprits.
Non-allergic drug reactions are side effects that do not involve your immune system. They can be quite bothersome and are often confused with drug allergies. Allergic drug reactions usually begin right after you take the medication, but you may develop a drug allergy after taking a medication for several weeks, even when you’ve had no reaction to it in the past.
The most severe drug allergy symptom is whole-body inflammation, a condition called anaphylaxis that may be life-threatening. If you develop anaphylaxis, you must immediately contact emergency services and use an epinephrine (adrenaline) auto-injector, if available.
Symptoms of Drug Allergies:
- Hives (urticaria)
- Facial swelling
- Shortness of breath, cough, wheezing
- Runny nose
- Itchy, watery eyes
- Vomiting or diarrhea
Causes of Drug Allergies:
A drug allergy happens when your immune system incorrectly identifies a drug as a harmful intruder, like a bacteria or virus. Your body then develop an antibody against that medication. These antibodies may develop after the first or after several doses.
The next time you take the drug, your antibodies mark the drug for destruction by your immune cells. Chemicals released by this immune cascade cause your drug allergy symptoms, especially histamine release.
Some of the most common offenders in drug allergies include aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen/Advil and naproxen/Aleve. Others are antibiotics such as penicillin, x-ray dyes, chemotherapy drugs and, only very rarely, vaccines can cause drug allergies.
Treatment Options for Drug Allergies:
- Medications – medications can help control your drug allergy symptoms, such as antihistamines like diphenhydramine/Benadryl and cetirizine/Zyrtec, and corticosteroids like prednisone. We also prescribe an epinephrine (adrenaline) auto-injector that will give you quick relief during an attack.
- Grades challenges – if a diagnosis of a drug allergy is unknown and one of our providers feels that you are at low risk for a reaction, they may recommend a graded challenge. With this procedure you receive a small amount of the drug initially and then gradually increase to the desired dosage. If you tolerate the therapeutic dosage, you are not considered allergic to that drug.
- Drug desensitization – In many cases, allergic sensitivity can be reduced by starting with a very small dose and gradually increasing dosage over time. This technique is done under close medical supervision at our allergy clinic.
Our specialists will work closely with you to help diagnose and treat your drug allergies. Research shows that drug allergies are often misdiagnosed and can limit use of the most effective medication available to you.