Patch Testing: What to Expect

What is Patch Testing?
Patch testing is a diagnostic skin test performed in-office to identify substances (allergens) that may be causing your rash, known as allergic contact dermatitis. Common triggers include jewelry, perfumes, cleaning products, latex, and poison ivy. This test does not identify food allergies.

What is Allergic Contact Dermatitis?
Allergic contact dermatitis occurs when your immune system reacts to specific substances on your skin, causing areas of inflammation. These allergens do not cause rashes in most people, but in some individuals, they trigger persistent symptoms such as scaly, itchy rashes, hives, or blisters. The most effective treatment is identifying and avoiding the allergen, which patch testing helps to achieve.

How Does Patch Testing Work?
Patch testing involves placing small patches containing potential allergens on your back. The process takes 5 days:

• Monday: Patches are applied and marked. These remain on your back for 48 hours. Avoid getting them wet, sweating excessively, or exposing them to sunlight.

• Wednesday: Patches are removed, and the skin is evaluated or photographed. You may shower afterward.

• Friday: A second evaluation determines initial reactions.

• Monday (Optional): A follow-up may check for late reactions.

Is it Painful?
Patch testing is painless. However, positive reactions may cause mild irritation, itching, or blisters, which are temporary and treatable.

How to Prepare for Patch Testing

To ensure accurate results, please follow these guidelines:

• Medications and Topicals to Stop:

  • Stop using topical steroids, tacrolimus (Protopic), or pimecrolimus (Elidel) 1 week before testing.

  • Avoid oral steroids like Prednisone (>10 mg/day) 10 days before testing or taper as directed.

  • Do not receive intramuscular steroid injections 3 weeks prior.

• Other Preparations:

  • Avoid sun exposure or UV therapy on the test area for 2 weeks prior.

  • Arrive with a clean, rash-free back with no lotions, creams, or sunblock applied.

Test Results and Follow-Up

• Interpretation: Results are graded from negative (no reaction) to extreme (strong reaction). Strong reactions may cause blisters or ulcers, which are treatable.

• Next Steps: You’ll receive personalized guidance on avoiding allergens and alternative product recommendations. As members of the American Contact Dermatitis Society, we access a database to provide a detailed list of safe products tailored to your test results.

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Billing and Insurance

Patch testing is considered a procedure and may involve significant out-of-pocket costs, depending on your insurance plan.

• Self-Pay Rate: $850 for all four visits (Monday, Wednesday, Friday, and the following Monday).

• Billing Codes: 99214 and 95044 x 65.

We recommend contacting your insurance provider to confirm coverage and out-of-pocket expenses. If insurance denies coverage, you are responsible for the total cost.

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Summary of Your Schedule

• Monday: Patches applied (do not get wet).

• Wednesday: Patches removed, evaluation or photographs taken (you may shower afterward).

• Friday: Preliminary interpretation and consultation.

• Monday (Optional): Final evaluation for late reactions.

riday (to read results). There are even some late reactions on the following Monday which may be relevant​