It might be. If eczema isn't clearing even though you've been treating it faithfully, the rash may be something else, or eczema plus something else. Allergic contact dermatitis, psoriasis and fungal infections are common look-alikes, and each needs a different plan. A dermatologist starts by rechecking the diagnosis, then adjusts treatment, and may suggest patch testing if an allergy to something touching your skin seems likely.
Switching creams again rarely helps when the diagnosis is off. Here is what a dermatologist looks at, what patch testing involves, and how to prepare.
Why a second look at the diagnosis often comes first
Eczema (atopic dermatitis) is usually diagnosed by looking at the skin and asking about your health history. There is no single test that proves it. So a rash can be labeled eczema when it is actually something that looks similar.
When treatment isn't working, a dermatologist will usually consider a few possibilities:
- The rash is a different condition that needs a different treatment.
- There are two problems at once. For example, eczema plus an allergy to an ingredient in a cream, or eczema with an infection on top.
- A trigger is still present, such as a product, a work exposure or frequent handwashing.
- The plan needs adjusting, because the treatment isn't strong enough, isn't the right form for that area, or is hard to use as directed.
Sorting this out starts with a close exam and a careful history. If needed, a dermatologist may use simple tests, such as looking at a skin scraping under a microscope or, less often, taking a small skin sample (biopsy) to rule out other causes.
Look-alikes a dermatologist considers
Allergic contact dermatitis. This is an allergic reaction to something that touches your skin. According to the American Academy of Dermatology (AAD), fragrance and nickel are among the most common causes. The rash often appears hours to days after contact, which makes the cause hard to spot on your own. A useful clue is a rash that matches where something touches you: earlobes and wrists (jewelry, watches), the belly (belt buckles, jeans snaps), eyelids (makeup, hair products) or hands (gloves, cleaning products). Ingredients in moisturizers, and even in medicated creams, can be the cause.
Irritant contact dermatitis. This is not an allergy. It is damage from repeated contact with things like water, soap and cleaners, and it is common in people who wash their hands often or work with their hands in water.
Psoriasis. Psoriasis patches tend to be thicker, with sharper edges and more scale than eczema. On lighter skin they often look pink or red with silvery scale. On brown and Black skin they may look purple or dark brown with gray scale. Psoriasis often shows up on the elbows, knees, scalp and lower back, and it can cause pitted or thickened nails.
Fungal infection (ringworm or tinea). A fungal rash can be scaly and itchy, often with a raised edge that slowly spreads outward. Steroid creams used for eczema don't treat fungus, and they can change how a fungal rash looks, which makes it harder to recognize.
Other rashes. Scabies causes intense itch that is often worse at night and may affect others in your home. Seborrheic dermatitis causes greasy scale on the scalp, eyebrows and sides of the nose. Some types of eczema, such as coin-shaped (nummular) patches or small itchy blisters on the hands and feet (dyshidrotic eczema), may need a different approach than typical atopic dermatitis.
What patch testing is and when it's used
Patch testing helps find the cause of allergic contact dermatitis. It is usually done by dermatologists or allergists.
How it generally works:
- Small amounts of common allergens are placed under patches, usually on your back.
- You keep the patches on, and dry, usually for about 48 hours, avoiding heavy sweating and showers.
- You return so the patches can be removed and the skin checked.
- You return again a few days later for a second reading, because some allergic reactions take days to appear.
If something causes a reaction, you learn which ingredients to avoid and how to spot them on labels. Avoiding a confirmed trigger often helps the rash settle, though individual results vary.
Patch testing looks for delayed skin reactions. It is different from the skin-prick and blood tests used to check for food or pollen allergies.
Dermatologists may suggest patch testing when a rash keeps coming back, sits in a spot that points to something touching the skin, or doesn't respond to eczema treatment as expected. Before testing, the testing office will tell you what to avoid, such as sun on your back or certain creams on the test area. Don't stop a prescribed medicine unless the doctor who prescribed it tells you to.
Bay Ridge doesn't offer patch testing. Here is what it does instead.
Bay Ridge Dermatology, in Bay Ridge, Brooklyn, does not offer patch testing. What the practice does offer is a careful evaluation of a rash that hasn't improved, and treatment for the conditions most often behind it. As part of its medical dermatology care, the practice treats:
- Eczema and atopic dermatitis, in patients from infants through seniors
- Psoriasis
- Rashes
- Skin infections
The practice also offers the XTRAC excimer laser, an FDA-cleared laser used for psoriasis, vitiligo and atopic dermatitis. Whether any treatment fits you depends on your exam.
If your clinician thinks patch testing would help, ask at your visit about the next step for having it done. If you are looking for patch testing in Brooklyn on your own, keep in mind that not every dermatology office offers it, so call ahead and ask before you book. Some allergists offer patch testing too.
A product and exposure diary to bring to your visit
For about two weeks before your appointment, keep notes on:
- Every product on your skin and hair: cleanser, moisturizer, sunscreen, makeup, shampoo, conditioner, hair dye, deodorant, and the medicated creams you use.
- Household products: laundry detergent, fabric softener, dryer sheets, dish soap, cleaning sprays.
- Metals and materials: jewelry, watches, belts, glasses frames, gloves, new clothing or shoes.
- Work and hobbies: how often you wash your hands, chemicals you handle, gardening, crafts.
- Where and when the rash flares, with photos on bad days.
- Every treatment you've tried: the name, how often you used it, for how long, and what happened.
Bring the products themselves, or clear photos of their ingredient labels. Our page on what to expect at your visit covers the rest of what to bring.
When to see a dermatologist rather than switching products again
Book a visit if:
- The rash hasn't improved after a few weeks of consistent treatment, or keeps returning in the same place
- It is spreading or getting worse while you treat it
- Itch is disrupting your sleep, work or school
- It affects your face, eyelids, hands, feet or genitals
- It is ring-shaped, has a spreading edge, or others at home are itchy too
- You've used a steroid cream for a long time without lasting relief
Contact a doctor promptly for signs of infection, such as yellow or honey-colored crusts, pus, or spreading warmth and redness. Get medical care right away if you have a fever with the rash, or sudden clusters of painful blisters or sores, which can be a sign of a serious infection.
If you've been going in circles with a rash, a fresh look can help. You can book online or call (347) 497-4984, and bring your diary along.
This article is general information, not medical advice. For advice about your own skin, see a dermatologist.