Got a rash? Don’t freak out. Before you reach for steroids or creams to cure it, keep in mind that treating unexpected skin irritation begins with a proper diagnosis. Unfortunately, because irritated skin often shares the same symptoms, it can be one of the hardest conditions to identify. Here, dermatologists break down four of the most frequently misdiagnosed skincare conditions—eczema, rosacea, psoriasis and dermatitis—and how to differentiate among them.

Psoriasis

Put simply, psoriasis is a condition in which your immune system gets angry at your skin and attacks it. The most common variation is plaque psoriasis, which appears as thick, raised plaques on the skin. These plaques are often silvery in nature—and very, very itchy. “Psoriasis usually shows up on or around the scalp, but is also common behind the ears, on the elbows, knees and lower back,” says Amy S. Ross, M.D., a board-certified dermatologist in Tampa, Fla.

If you’re dealing with a suspected case of psoriasis, it may be safer to see a dermatologist from the start. While a variety of topical treatments may help improve symptoms of psoriasis, it’s important to understand that your case is internal. Severe psoriasis may require treatment with powerful medications such as Trexall, Dithranol or Sandimmune that suppress your immune system.

Rosacea

Rosacea is most commonly identified by severe flushing of the skin—it can also cause acne-like bumps, hotness and, in extremely rare cases, swelling. These symptoms often come and go, depending on a person’s triggers, which can range from spicy foods to excess stress. According to Vanessa Coppola, a board-certified nurse practitioner and aesthetic specialist, the most telling indicator of rosacea versus other conditions is its location. “Rosacea is usually limited to the face and the eyes,” she says. “If you suspect rosacea, check to see if your face is flushed and if your capillaries are broken.”

If your inflammation is mild in nature, Naissan O. Wesley, M.D., a board-certified dermatologist in Beverly Hills, Calif., suggests using an antibiotic or lightweight moisturizer, combined with a skin-calming serum. Alternatively, you can also ask your doctor about laser treatment, blood pressure medication or electrodesiccation—use of a tiny needle that delivers electricity to the blood vessel to destroy it—for long-term results.

Dermatitis

There are two types of dermatitis, and in most cases, it’s likely that your dermatitis is a one-time thing, says Wesley. Allergic contact dermatitis, which manifests as itchy red patches and blisters, is caused by an allergic reaction to a material, such as jewelry metals, cosmetic products, fragrances and preservatives. Keep in mind that it can take several days after exposure for a rash to develop.

Similarly, irritant contact dermatitis occurs when a chemical substance (e.g., acids, alkalines, hair dyes, resins, etc.) irritates the skin’s outer layers. The rash is more painful than itchy, and is typically short-lived. The best way to identify—and eliminate—any form of dermatitis is to consider any new products or environments you have been exposed to recently. You may need to use some process of elimination, but this can help you find the incriminating culprit.

Eczema can occur at all ages and tends to run in families.

Eczema

Eczema can occur at all ages and tends to run in families, especially those prone to allergies and asthma. The condition often appears as dry, red and itchy skin that worsens with excessive itching. Affected areas may also become cracked, discolored, blistered, scaly and may weep clear fluid. Although eczema can crop up anywhere, Wesley suggests looking for markings on the crease of your wrists, elbows and knees, as well as reddening on the ankles, face and neck.

If you struggle with chronic eczema, Wesley advises against using harsh, overly drying cleansers, as these can worsen the condition. Instead, moisturize regularly with gentle, fragrance-free products that have the National Eczema Seal of Acceptance. “Maintaining the skin barrier with good moisturization is a key component in reducing and preventing symptoms,” she says.

When to see a dermatologist

“The duration of skin inflammation is often dependent on the individual,” says Wesley. “Stress, lifestyle, diet and types of treatments all play a role as to how severely and how long people suffer from these conditions.” The fact is, living with psoriasis, dermatitis, eczema and rosacea shouldn’t have to come with major disruptions.

In determining whether to seek professional medical treatment, it’s best to monitor your symptoms. If your particular skin condition begins to crust, ooze or grow rapidly in size—or it’s hindering your day-to-day activities—Coppola advises seeking out a dermatologist.

Wesley points to the duration of your condition as another indicator: “If a skin condition has been present for several months and is not resolving, or a new mole or growth has appeared, I would recommend seeking professional expertise sooner rather than later.”