Drug Allergy: Diagnosis and Treatment

Reviewed by Christine B. Cho, MD

How Are Medication/Drug Allergies Diagnosed?

Every diagnosis begins with a detailed medical history and physical examination. The doctor will ask lots of questions about the nature of the reaction, such as if the person had taken the medication or a similar medication before, how long the person was on the medication, timing of the dose, onset of symptoms and the nature and evolution of the symptoms. Since the medication allergy may be genetic, expect some questions about other family members who may be allergic.

Depending upon the findings of the initial evaluation, the following tests may be necessary:

  • Allergy skin testing may be performed to check for presence of allergic antibodies to selected drug allergens. Patch skin testing can also be performed.

  • Blood testing is occasionally indicated.

  • Sometimes a challenge to the suspected drug is necessary to confirm the diagnosis. If indicated, drug challenges are coordinated with safety as the highest priority.

 

What Is the Treatment for Medication/Drug Allergy?

The best way to treat drug allergy is to avoid the medication and other medications in its class, since there is no cure for allergy. Antihistamines and steroids can be used to alleviate symptoms, but once a drug allergy is determined, the medication should be avoided.

In very rare cases, it may be required to ‘treat through’ a medication allergy. That is, the drug may be required despite the reaction. This can be dangerous and is only used as a last resort. A person may be pre-treated with steroids or antihistamines in such cases. In addition, if a person requires a drug/medication to which he/she is allergic, drug desensitization can be performed in a hospital setting.

A person is given gradually increasing doses of the medication either by mouth or by IV under constant monitoring until they can tolerate a full dose. It is very important to remember that desensitization works only for that particular course of the medicine, so if it is discontinued, the person once again becomes allergic and needs to be desensitized each time the medicine is administered.

 

What Is the Role of National Jewish Health?

Board certified allergists at National Jewish Health evaluate and treat a number of allergic conditions. Patients seen in our Outpatient Clinic, Day Program, or Pediatric Inpatient Service for evaluation of possible medication reactions undergo a comprehensive evaluation including a thorough history and physical examination.
Depending upon the findings of the initial evaluation, the following tests may be necessary: allergy skin testing, laboratory testing and blood work. Occasionally, a challenge to the suspected drug is necessary to confirm the diagnosis. If indicated, drug challenges are coordinated with safety as the highest priority. National Jewish Health has a state-of-the-art challenge facility with extensive experience and an excellent record in the performance of medication challenges. If you would like to schedule an appointment for evaluation of possible drug allergy, please contact our LUNG LINE at 1.800.222.LUNG (5864).

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