Drug challenge in the allergy clinic (1308)

What is a drug challenge?

This procedure is done to see if a patient can take a medicine that caused a reaction in the past.

When is a drug challenge done?

• When medicine is needed to treat a condition.
• If history suggests a penicillin allergy and recent allergy testing was negative.

Why is it done in the clinic?

• There is a risk for allergic reaction. The clinic has supplies and staff to treat a reaction.

What happens during a clinic drug challenge?

• Questions will be asked and an exam will be done.
• There will be a breathing test if the patient has asthma or breathing problems.
• The patient will take a small amount of the medicine. If there is no reaction after 20 to 30 minutes, a larger amount will be given. This is often done in 1 to 3 steps.
• The patient will stay to be watched for up to 1 hour after the last dose.
• A clinic drug challenge normally lasts about 2 to 3 hours.

How do I prepare for a drug challenge?

• The clinic will often supply the medicine.
• If you are able, stop all antihistamines for 3 days before the challenge.
  Common names include: Benadryl® (diphenhydramine), Zyrtec® (cetirizine), Claritin© (loratadine), Allegra® (fexofenadine), Xyzal® (levocetirizine), Clarinex® (desloratadine), Vistaril®/Atarax® (hydroxyzine). Be careful if taking cold medicine. They can also contain antihistamines. If you are unable to stop your antihistamines, please let your provider know you are still taking them.
• Keep taking all other medicines. Do not stop asthma medicines.
• Bring activities or a book to read. You may also bring a drink.

Who should not have a drug challenge?

A drug challenge should not be done:

• If there is a history of serious or life-threatening reaction to the drug.
• When you are sick or have coughing, wheezing or breathing problems. Albuterol may be used for exercise or activity within 3 days of the challenge. Call the clinic if it has been used in the last 3 days. The patient may need to reschedule. This is done for the patient’s safety.
• If the patient is taking beta blocker medicines for high blood pressure, migraine headaches, or eye drops for glaucoma. Common names are: Propranolol, Metoprolol, Atenolol, Timolol or Betaxolol.

What are the risks?

Mild reactions may happen during or after the challenge. They include:

Rash, a few hives, eczema that gets worse, diarrhea, sneezing, stuffy nose, runny nose, a change in behavior or a headache.

Serious reactions do not happen often, but can be very serious. They can lead to death if not treated. Tell the nurse right away if you have any of the following:

• Hives. Rash, swelling or itching of more than one part of the body.
• Swelling. Any part of the body, inside or out. This includes the mouth, tongue or throat. It can be one or many parts of the body.
• Breathing problems. Shortness of breath, coughing, wheezing or chest feeling tight.
• Other. Constant sneezing, feeling dizzy, stomach ache, nausea or just not “feeling right.”
• Anaphylactic shock is the most serious allergic reaction. It can be a combination of any of the above symptoms and can be life threatening. It can happen in a few minutes or up to 24 hours after the medicine has been given. It is important to watch for anaphylaxis, but it is does not happen often.

Call 9-1-1 if any of these symptoms happen after leaving the clinic!

What happens if a reaction happens?

• If the patient has a reaction, the challenge is stopped.
• Continue to avoid that medicine and to talk with the doctor.
• If there is a serious or anaphylactic reaction, emergency medicine will be given right away. The medicine is called epinephrine and comes in an Epinephrine Auto-injector.
• By signing the consent form, permission has been given to do a drug challenge and treat any reactions.

What happens after a clinic drug challenge?

• Watch for a delayed reaction.
• If there is a reaction at home take medicine to treat the reaction. Go to the emergency room if needed. Call the Allergy Clinic.
• If there is a reaction to the medicine, the patient will need to continue to avoid it. Some medicines are part of a larger family or class of drugs and all related medicines may also need to be avoided.
• If there is no reaction during the challenge, the medicine can be used as directed by your provider. The medicine will be taken off of the patient’s allergy list.