How to Prepare for Your Allergy Testing Appointment

December 1, 2025
Health & Wellness

Expert Advice from Michael D’Netto, M.D.

If you’re experiencing unexplained sneezing, rashes, or breathing issues, allergy testing can help identify the cause—and lead to lasting relief. At WinnMed in Decorah, Michael D’Netto, M.D., a Mayo Clinic Health System board-certified Allergist and Immunologist, offers comprehensive allergy evaluations to pinpoint triggers and personalize treatment.

Here’s how to prepare for your appointment to ensure the most accurate results:

1. Stop Taking Antihistamines

Antihistamines can interfere with skin test results. Dr. D’Netto recommends stopping:

  • Over-the-counter antihistamines (like loratadine, cetirizine, or diphenhydramine) at least 5 days before testing
  • Some prescription medications may also need to be paused—check with your provider first 

“Stopping antihistamines before testing is crucial,” says Dr. D’Netto. “They can block the skin’s reaction and lead to false negative results. However if these medications cannot be stopped, blood testing, which is not impacted by antihistamines, can be considered.” 

2. Noting to East or Drink, Except Water

At least two hours prior to the appointment, Dr. D’Netto recommends nothing to eat or drink – except water – so the allergy testing is performed on a largely empty stomach.

3. No Vigorous Activity

Vigorous exercise can alter the body’s reaction and interfere with test results. Avoid vigorous activity for at least one hour prior to testing.  

4. Bring a Symptom Diary

Note when your symptoms occur, what you were exposed to, and any patterns you’ve noticed. This helps guide which allergens to test.

5. List All Medications

Bring a list of all medications and supplements you’re taking. Some may need to be adjusted before testing.

6. Wear Comfortable Clothing

Wear short sleeves or loose-fitting clothes to allow easy access to your arms or back for testing.

What to Expect

Dr. D’Netto will review your medical history, perform a physical exam, and conduct skin or blood tests based on your symptoms. Allergy skin test results are available the same day.

“Allergy testing is safe, quick, and incredibly helpful,” Dr. D’Netto adds. “It’s the first step toward feeling better and taking control of your health.”

Make an appointment

Dr. D’Netto is accepting new patients at WinnMed in Decorah.  Call WinnMed at 563-382-2911 or request an appointment online through WinnMed’s online portal, MyChart.

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