Allergy Patch Testing

If you're experiencing ongoing skin irritation, rashes, or eczema that won't go away, you may be dealing with allergic contact dermatitis—a skin reaction caused by exposure to allergens in everyday products. At our San Francisco and Marin dermatology clinics, we offer advanced patch testing using the NA-C 80 panel, a comprehensive and highly accurate way to identify what's triggering your skin condition.

About Allergy Patch Testing

Patch testing is a non-invasive diagnostic method that helps pinpoint the specific allergens causing delayed skin reactions. Unlike food or environmental allergy tests, patch testing focuses on substances that come in direct contact with your skin, such as fragrances, preservatives, metals (like nickel), rubber, and other chemicals found in personal care products, clothing, or workplace materials. This type of testing is especially beneficial for individuals with chronic rashes, eczema, or sensitivities that haven’t responded to traditional treatments.

At our San Francisco and Marin dermatology offices, we use the NA-C 80, the most up-to-date testing series developed by the North American Contact Dermatitis Group. This panel includes 80 of the most common contact allergens in North America, significantly increasing the chances of identifying the exact cause of your skin reaction. During your patch test, these allergens are applied to your back using small adhesive patches. You’ll wear the patches for 48 hours, then return for two follow-up visits—usually at 48 and 72–96 hours—to assess your skin's reaction.

Benefits of Allergy Patch Testing

• Accurate identification of specific contact allergens causing skin irritation or rashes
• Personalized recommendations to help you avoid triggers in skincare, cosmetics, clothing, and more
• Non-invasive testing with minimal discomfort and no needles involved
• Targeted treatment plans that go beyond symptom management to address the root cause

Common Allergens Tested in the NA-C 80

The NA-C 80 panel screens for a wide variety of allergens found in everyday environments, personal care items, and occupational settings. Some of the most frequently identified allergens include:

• Fragrances – Found in perfumes, soaps, lotions, shampoos, and cleaning products. Fragrance mix I and II are commonly tested.
• Preservatives – Such as methylisothiazolinone (MI), formaldehyde, and parabens, used in cosmetics, moisturizers, and household products.
• Metals – Nickel sulfate is a top offender, often found in jewelry, eyeglass frames, belt buckles, and electronics. Cobalt and chromium are also common.
• Rubber Compounds – Including substances like thiurams and carbamates, found in gloves, shoes, and elastic materials.
• Hair Dye Ingredients – Such as para-phenylenediamine (PPD), which is often present in dark hair dyes.
• Topical Medications – Including neomycin and bacitracin, which are common ingredients in over-the-counter antibiotic ointments.
• Adhesives and Resins – Found in bandages, medical tapes, and even some athletic equipment.

Identifying these allergens can be life-changing for patients who have been struggling with unexplained or recurring skin conditions. Once your specific sensitivities are known, our dermatology team will help you avoid these triggers and find safe, skin-friendly alternatives.

The benefit of patch testing with the NA-C 80 is not just in getting a diagnosis, but in creating a clear, personalized plan to avoid future flare-ups. Once we identify your triggers, our dermatology team will guide you on how to avoid those allergens in your daily life—whether in skincare products, clothing materials, or occupational exposures. Many of our San Francisco and Marin patch testing patients report significant improvements in their skin after making targeted lifestyle changes based on their results.

If you’re tired of dealing with stubborn skin issues and want real answers, patch testing at our San Francisco and Marin dermatology clinics can help you uncover the cause and take control of your skin health. Contact us today to schedule your consultation.

Frequently Asked Questions

What is a patch test and how will it look like?

In this process, small amounts of 80 common allergens are applied to the back via patches for a few days. The skin’s reaction to these allergens is then monitored to determine any sensitivities or allergic reactions. While you have your patches on, you may experience itching.

How long do I have to wear the patches for?

The patches will be removed in 2 days, and a first reading will be made 20 minutes after the removal. You will then come back 2 or 5 days after the removal for a final read.

What should I consider during test time?

No prednisone 2 weeks prior to patch testing. No topical steroids or prolonged sun exposure on the back for 1 week prior to patch testing.

No excessive hair on the back. Patients may shave 1–2 days before. No lotions or emollients on test day.

Can I do anything about the itchiness?

Try not to scratch the test site. This is a sign of an irritant reaction. Antihistamines such as Zyrtec and Allegra are okay to take.

What are the benefits to patch testing?

Your dermatologist will tell you what you are allergic to, including what common household products to avoid.