Drug Allergy

Drug Allergy

Everyone reacts to medications differently. Certain medications have known side effects that can be common in many patients. Certain medications have known but rare side effects that are reported by few patients. Allergic reactions occur when your immune system sees a drug as foreign and reacts by making antibodies called IgE. This kind of allergic reaction can lead to life-threatening anaphylaxis. Other adverse reactions to medications are immune mediated but not related to IgE. These are often reactions that affect the skin. All medications have the potential to cause side effects, but only about 5 to 10% of adverse reactions to drugs are allergic. Always call your doctor if you have side effects that concern you, or you suspect a drug allergy has occurred. If your symptoms are severe, seek medical help immediately.

Non-Allergic Reactions

Non-allergic reactions are much more common than drug allergic reactions. These reactions are usually predictable based on the properties of the drugs involved. Symptoms of non-allergic drug reactions vary, depending on the type of medication. People being treated with chemotherapy often suffer from vomiting and hair loss. Certain antibiotics irritate the intestines, which can cause stomach cramps and diarrhea.

Non-Allergic Reactions

Antibiotics are the most common cause of anaphylaxis. While it is reasonable to initially consider a medication allergy when a person experiences certain symptoms while taking the medication, it is also important to have a proper diagnosis. Given the resistance to antibiotics of certain bacteria, there are recent guidelines recommending testing for antibiotic allergy in patient previously labeled with a penicillin allergy. Ninety (90%) percent of patients labeled with a penicillin allergy, once tested and challenged, will no longer be allergic to penicillin!

A few facts about drug allergy from the American Academy of Allergy, Asthma and Immunology:

90% of people with a history of penicillin allergy who are tested to Penicillin will have negative skin testing, pass the oral challenge stage, and be able to utilize penicillin products when needed

Look out for the most severe form of delayed drug reactions that not only cause rashes but may also involve other organs including the liver, kidneys, lungs, and heart. Blisters may be a sign of serious drug reactions called Stevens-Johnson Syndrome and Toxic epidermal necrolysis (TEN), where the surfaces of your eye, lips, mouth and genital region may be eroded. This needs immediate medical attention.

Not all drug allergic reactions involve a specific immune reaction. Some people experience flushing, itching or a drop in blood pressure from intravenous dyes used in x-rays or CT scans. If you take angiotensin converting enzyme (ACE) inhibitors for high blood pressure, you may develop a cough or facial and tongue swelling.

Some people are sensitive to aspirin, ibuprofen or other non-steroidal anti-inflammatory drugs (NSAIDs). One type of aspirin or NSAID sensitivity may cause a stuffy nose, wheezing and difficulty breathing. This is most common in adults with asthma and in people with nasal polyps (benign growths). Other reactions to NSAIDs can result in hives or in rare instances, severe reactions can result in shock.

Contrary to popular myth, a family history of a reaction to a specific drug typically does not increase your chance of reacting to the same drug.

If you have a history of reactions to different medications, or if you have a serious reaction to a drug, an allergist / immunologist, often referred to as an allergist, has specialized training to diagnose the problem and help you develop a plan to protect you in the future.

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