Drug Allergy

A drug allergy is the abnormal reaction of your immune system to a medication. Any medication: over-the-counter, prescription or herbal, can cause a drug allergy. However, certain medications are more likely to cause drug allergy. A drug allergy is not the same as a drug adverse reaction, which is a well known possible reaction that is listed on a drug label. A drug allergy is also different from drug toxicity which is caused by an overdose of medication.

What are symptoms of drug allergy?

Typically, drug allergy symptoms involve hives, rashes, fever, and itchy skin. More serious reactions may present with difficulty breathing, dizziness, wheezing, swelling, vomiting, diarrhea, and anaphylactic shock. Severe reactions require immediate medical attention and can lead to hospitalization or death. Other organs in the body such as liver and kidneys may be involved. While drug allergies generally occur after the first dose of drug is taken, they can occur even after drug usage has been discontinued.

What are common drugs that cause drug allergies?

Antibiotics such as Penicillin, Sulfa drugs, and Quinolones are commonly linked to drug allergies.  Pain relievers such as Aspirin, Advil, Ibuprofen, and Aleve can cause allergy symptoms, which include hives, angioedema, asthma, and nasal polyps. Cancer chemotherapeutic agents are also known to cause drug allergies. Local anesthetics used for dental procedures can cause hives. Patients with one type of drug allergy are predisposed to developing other drug allergies. There is a familial tendency to develop drug allergies and patients with other allergy problems are at higher risk of developing drug allergies.

How are drug allergies evaluated?

A history, or past recollection of allergy incidents, may help in the determination of a true drug allergy as opposed to an adverse or a toxic dose reaction. While adverse reactions and toxic dose reactions can be minimized by decreasing the drug dosage, a drug allergy cannot be avoided with continued use of the medication. In some cases, patients have been misinformed that they have an allergy to a drug, while in fact they merely suffer from symptoms that are not allergy related. A physical exam is important in determining the type of reaction the patient has suffered.

Laboratory tests help to evaluate the severity of allergic drug reactions. Allergy skin tests may help to determine if there is a true allergy. Penicillin skin tests with an oral drug challenge are used to determine if you have penicillin drug allergy. Patch testing can also be used to evaluate for drug allergies.

What can be done about drug allergies?

Avoiding the drug causing the allergy is extremely important as further usage can trigger more severe allergic reactions. It is important to use oral medications and or topical creams when treating the acute symptoms of drug allergy. Drug allergy reactions can persist even after discontinued drug usage.

If a drug needs to be used and a patient is allergic to it, a process known as desensitization can make a person non-allergic to the drug so they can safely take it. Drug desensitization protocols including Penicillin and Aspirin are available for patients who have allergies to these medications.  This process will allow patients to temporarily take these medications. Once the patient stops taking the medication, the patient becomes allergic to that drug again.