If you’re dusting flakes off your shoulders enough to instinctively avoid your black shirts, then you might think you have an especially stubborn case of dandruff. But there’s a chance you could actually have scalp psoriasis, a form of the chronic skin condition that extends to the scalp, hairline, and ears.
Scalp psoriasis has a lot in common with dandruff, also known as seborrheic dermatitis; the two conditions involve scaly or dry patches on the scalp as well as flakes. In fact, they’re so similar that “we sometimes even use the term ‘sebo-psoriasis’ to describe overlap between seborrheic dermatitis and psoriasis,” says Joseph Merola, MD, a board-certified dermatologist at UT Southwestern Medical Center. But that mistaken identity can keep you from using the right treatment and getting some relief. With that, here’s how to tell them apart.
Why psoriasis and dandruff get confused
Itchiness, flakes, inflammation: These are typical signs of both psoriasis and dandruff. But you can find subtle clues to tell them apart, since they can differ in their appearance, location, and severity. Let’s start with the causes: Scalp psoriasis is an autoimmune condition that leads to the overproduction of skin cells, which build up and create the telltale plaque on the skin. Dandruff, on the other hand, stems from an overgrowth of a yeast (which naturally lives on the scalp) that triggers inflammation.
First, scope out the flakes. You might see finer, looser flakes with dandruff, while psoriasis flakes are thicker. And if you (or a doctor) are able to look beyond your hair follicles, “scalp psoriasis usually causes a thicker, more stubborn scale that sticks to the scalp and sits over clearly defined red patches,” says Dr. Merola. There can also be hints beyond your dome: Scalp psoriasis often involves the eyebrows and nasolabial creases (a.k.a. the smile lines), whereas dandruff is usually confined to the scalp. “Psoriasis may also involve other areas such as the elbows, knees, nails, or skin folds, and a family history is often present,” says Dr. Merola.
And then there’s the intensity. Dandruff can be embarrassing and uncomfortable in its own right, but scalp psoriasis has the potential to be debilitating, as Mark Lebwohl, MD, a board-certified dermatologist at Mount Sinai, puts it. “Some patients will have such bad scalp psoriasis that it’s like having their head in a hard cap all day,” he says. Rather than being just itchy, it’s downright painful. And some people experience scalp psoriasis so severe and inflamed that they even lose their hair as a result.
How to address your scalp concerns
Both dandruff and mild cases of scalp psoriasis can improve if you use over-the-counter treatments found in the drugstore—namely, medicated shampoos. “Products containing ingredients like zinc pyrithione are generally safe, and may even help patients who have overlap between dandruff and psoriasis,” says Dr. Merola.
However, “if it’s not going away with simple, easy over-the-counter remedies like shampoos, you should be seen by a dermatologist,” says Dr. Lebwohl, who adds that if you wash your hair daily, then you should expect some improvement in a week. If your symptoms remain after, or they tend to be very painful, disrupt your sleep, or are accompanied by shedding, then make an appointment. A dermatologist can prescribe topical corticosteroids (which are the first-line treatment). And for severe cases, “we now also have highly effective oral and injectable medications that can increasingly get patients clear or almost clear when topical therapy is not enough,” says Dr. Merola.
Why it’s important to know the difference
If you’re treating the wrong thing, you might never get relief. “Psoriasis is often fixed, meaning it stays unless it’s very actively treated,” says Dr. Lebwohl. “It doesn’t just wax and wane.” Seborrheic dermatitis, on the other hand, can be cleared completely with the right shampoo.