Dr. Matthew Innes · Board-Certified Dermatologist · TheFrugalDerm.com

Patch Testing
What to Know & What to Expect

A systematic approach to identifying what's causing your skin reaction — for good

Nurse line: 801-776-7129  ·  After hours (Dr. Innes): 801-414-8443  ·  Website: thefrugalderm.com

What Is Patch Testing?

Allergic contact dermatitis is a form of eczema caused by something coming into contact with your skin — fragrances, preservatives, metals, and thousands of other chemicals can trigger it. Without patch testing, identifying the culprit is often a guessing game.

Patch testing allows us to pinpoint exactly what you are allergic to. Once we know, we can remove specific allergens from your environment and routine — with the goal of curing your rash, not just treating it.

✓ Positive Reactions

Dr. Innes will give you a personalized "safe list" of products that do not contain your identified allergens — so you can shop with confidence.

No Reactions

Also useful — it means your eczema is very likely not allergic in nature, and we'll pursue a different treatment path.

⚠ What Patch Testing Does Not Test For

We patch test to contact allergens only — things that physically touch your skin. We do not test for food allergies, pet allergies, or environmental allergens (pollen, dust, mold). Those cause different types of reactions, not contact dermatitis.

Insurance & Cost

Patch testing is generally a covered service. To confirm your coverage, call your insurance company and provide these codes:

Codes to Give Your Insurance Company
Diagnosis Code
L23.9
Allergic contact dermatitis, unspecified
CPT Code
95044 × 90
We typically apply 90 patches per session

Ask if patch testing is a covered service, whether you've met your deductible, and what your estimated out-of-pocket cost will be.

⚠ No-Show & Same-Day Cancellation Fee: $50

Preparing the patches is time- and labor-intensive for our nursing staff. If you need to cancel or reschedule, please let us know in advance. Text or call 801-776-7129.

The Process — Three Steps Over One Week

Patch testing requires two office visits plus one at-home step in between. Plan your schedule around these three fixed days:

1
Thursday — Office Visit
Patches Applied
Dr. Innes' team tapes the patch panels to your back. 90 allergens are included — there will be a significant amount of tape on your back for 48 hours. The patches must maintain solid, uninterrupted contact with your skin the entire time.
2
Saturday — At Home
Remove & Re-Mark
After approximately 48 hours, you remove the patches at home with the help of a family member or friend. You will also re-mark the patch sites on your skin. Specific instructions for this step are given at your Thursday appointment.
3
Monday — Office Visit
Reading & Results
Dr. Innes evaluates your reactions and reviews the results with you. If you have positive reactions, you leave with a personalized safe list of products that don't contain your identified allergens.

Before Your Appointment

☀️
Sun Exposure — 1 Week Before
Avoid sun exposure to your back for 1 week before your Thursday appointment. Tanned or sunburned skin interferes with accurate readings.
💊
Medicated Creams — 1 Week Before
Stop using steroids, tacrolimus, or other medicated creams on your back for 1 week before testing. You may continue using them on other areas of your body.
💉
Immune-Suppressing Medications
If you take prednisone, dupilumab, methotrexate, cyclosporine, or any similar medication, let Dr. Innes know before your appointment. These can suppress reactions and cause false negatives. You may need to taper before testing.

While the Patches Are On — 48 Hours

The most important rule: keep your back dry, still, and cool. Three things cause patches to detach:

💧
Water
🏃
Sweat & Movement
🔥
Heat

Keeping Your Back Dry

Your back must stay completely dry the entire 48 hours. Options for bathing:

🧽
Sponge bathe (avoid your back)
🚿
Wash hair in the sink or lean forward
🚿
Shower front only, keep back out of water
🛁
Shallow bath not reaching your back

After the patches are removed Saturday, water may run over your back — but do not scrub or use soap on the patch sites.

Avoiding Sweat & Physical Activity

  • Avoid vigorous exercise and strenuous activity for the full 48 hours
  • If your job involves significant physical activity or sweating, you will need to take time off or arrange lighter duties during the testing period
  • We can provide a physician's note for light duty if needed — just ask

Managing Itching

💡 Itching Is Often a Good Sign

Itching under the patches is expected and often means you're having a positive reaction — which is exactly what we're looking for. You may take antihistamines (Claritin, Zyrtec, Allegra, or Benadryl) to manage itch while the patches are on.

If itching becomes intolerable or you develop burning or pain under the patches, text Dr. Innes at 801-776-7129.

🚨 Rare Emergency — Know What to Do

If you experience swelling of the lips, tongue, or throat or difficulty breathing, remove the patches from your back immediately and call 911. This type of systemic allergic reaction is extremely rare, but it requires immediate emergency care.

What If the Tape Comes Off?

If a patch panel detaches, that portion of the test may need to be repeated — another round of patch placement. Only re-tape it if you are sure you are re-applying the squares exactly where they were before. Text us at 801-776-7129 and we'll advise you on next steps.


When to Contact Us

💬 Routine Questions & Scheduling

Text 801-776-7129 during business hours.

⚠ Intolerable Symptoms While Patches Are On

Text Dr. Innes directly: 801-414-8443

🚨 Emergency — Swelling of Lips, Tongue, Throat or Difficulty Breathing

Remove patches immediately and call 911.