Eczema, Psoriasis, and Seborrheic Dermatitis: What Are Their Differences, and Which One Do You Have?
It's not uncommon to head into winter dreading the itchy, flaky skin that often accompanies cold, dry weather. However, for over 31 million Americans living with eczema, 8 million Americans living with psoriasis, and 50 million Americans with seborrheic dermatitis, that itch continues year round. These ailments are undoubtedly common—which is why it makes sense that you might wonder if you're battling one. But how can you tell which one? Since they all make you itch, differentiating their symptoms can be a challenge. Luckily, Dr. Vivian Shi, dermatologist and speaker for the National Eczema Association, outlines the symptoms of each.
Commonly known as atopic dermatitis, eczema is "the itch that rashes," says Dr. Shi, meaning that an itching sensation often occurs first followed by a visible rash that develops after scratching. Eczema lesions are typically pink and scaly on pale skin tones, or a purple-to-brown color on darker skin tones, with accentuated skin lines. These patches get infected easily. Common eczema locations are the eyelids, neck, front of the elbows, and back of the knees. Eczema patients tend to have a higher risk of getting other allergic conditions, such as food allergies, asthma, and hay fever.
Psoriasis lesions are well-demarcated circular or oval-shaped thick plaques, with thick, silvery scales. Psoriasis can occasionally be itchy. A phenomenon commonly seen with psoriasis is koebnerization, explains Dr. Shi, where previously normal skin can develop psoriasis after trauma, such as scratching, site of surgery, or a cut. Psoriasis can affect any part of the body, but most commonly affects skin over the elbows and knees—and can be accompanied by nail psoriasis and psoriatic arthritis (a type of inflammation that can cause permanent joint destruction and disability).
Commonly known as dandruff, seborrheic dermatitis can be accompanied by varying degrees of skin inflammation and itching. This condition presents as a pink, scaly rash with a greasy-looking scale, explains Dr. Shi. It tends to develop in areas with high density of oil glands, such as the scalp, face, ears, and center of the chest and can occur on the scalp of infants (this is commonly known as cradle cap). Seborrheic dermatitis is thought to be due to yeast overgrowth on the skin, which ultimately causes the inflammation.
Getting the Right Diagnosis
As with any medical condition, seeking a proper diagnosis is critical to developing the right treatment plan. "The first and the most important part of caring for your skin condition is to get the right diagnosis," says Dr. Shi. "Various skin rashes can often look similar and have very different treatment approaches. For example, some over-the-counter psoriasis treatments work by reducing skin thickness and scaling, and if used incorrectly on eczema skin, can actually cause an eczema flare."
Dr. Shi says, "More often than not, people with these conditions may require a prescription strength medication. Therefore, it's better to see a dermatologist to confirm the correct diagnosis and get an individualized treatment plan." As each of the three conditions will fluctuate in severity over time, a treatment plan may require different approaches.