You can often tell the difference between psoriasis of the scalp and seborrheic dermatitis by the thickness of the scales that appear on your scalp. Psoriasis scales are typically thicker. Psoriasis is a multisystem inflammatory disease that is more challenging to treat than seborrheic dermatitis.

Having an itchy, flaky scalp is a common problem for many people. However, before you can figure out how to treat the condition, you must identify the cause.

Two conditions that can lead to an itchy scalp are psoriasis and seborrheic dermatitis. Although psoriasis and seborrheic dermatitis may seem similar, there are important differences between them:

  • Psoriasis is a chronic skin disease that can cause skin cells to grow so quickly that they accumulate on the surface of the skin. Patches of rough, scaly skin can appear anywhere on the body, including the scalp.
  • Seborrheic dermatitis is a chronic but manageable skin condition that can cause rough, scaly skin on the scalp and face. The noninflammatory variant of seborrheic dermatitis is dandruff. In babies, cradle cap is a common manifestation of seborrheic dermatitis, though it can also occur in other body areas, such as the groin or armpits.

Psoriasis tends to be pink or red with silvery scales on those with light skin tones. On medium skin tones, it can appear salmon-colored with silvery-white scales. On dark skin tones, psoriasis can appear violet with gray scales, or it can also appear darker brown and more subtle.

The patches can appear anywhere on the body, especially on the elbows and knees. They can also show up on the scalp. The patches can be itchy or tender to the touch.

Seborrheic dermatitis is usually found on the scalp, but it can sometimes appear elsewhere. It causes itchy patches of scaly skin that may look a little oily but can flake, especially if you scratch.

Seborrheic dermatitis may look different in individuals with skin of color. It tends to be red and scaly on those with light or fair skin tones.

On medium and dark skin tones this condition may appear as curved or petal-like lesions along the hairline. It can also cause hypopigmentation or lightening of the skin.

In babies, seborrheic dermatitis may have a crust-like appearance. Children and babies of color typically do not experience the typical cradle cap appearance of seborrheic dermatitis.

Instead, they often have redness, a rash, flaking, and hypopigmentation of the affected areas and folds of skin. Seborrheic dermatitis is often accompanied by overlying atopic dermatitis. Babies may also have seborrheic dermatitis around the eyes and nose.

With seborrheic dermatitis, if the skin is scratched, there’s some risk of bleeding or infection if the thick scale is picked or removed from the scalp.

Psoriasis and seborrheic dermatitis of the scalp share some common symptoms. They both result in:

  • scaly patches of skin
  • flakes that may attach to the hair shaft
  • itching

How can you tell the difference? Scales are one clue. Psoriasis on the scalp on light skin tones often appears as red or pink and can have silvery-white scales. On dark skin tones, psoriasis is more likely to appear as dark or reddish brown or purple patches with overlying whitish or grayish scales.

The scales of seborrheic dermatitis are usually thinner.

On light skin tones, the scales are more likely to be pinkish-yellow with yellowish flakes and an oily appearance. Individuals with light skin tones can also have redness alongside the flaking.

In individuals with medium and dark skin tones, redness may be seen alongside flaking. Sometimes the areas that are involved are lighter or darker than the individual’s normal skin tone. Some may also have a yellowish, oily appearance.

As for the patches, if you have psoriasis, you may only have scalp manifestations or have them on other parts of your body. If you scratch or try to remove them, they’ll probably bleed and may also become thicker and itchier.

Seborrheic dermatitis patches are usually easier to remove than those of psoriasis unless the patches require treatment. Psoriasis patches sometimes feel sore or tender, while seborrheic dermatitis may sometimes itch or burn.

It’s possible to have both scalp conditions at the same time, sometimes in the form of a little-understood condition called sebopsoriasis.

Anyone can get psoriasis of the scalp. There’s currently no way to prevent developing the condition. It’s more likely to occur in adults who have psoriasis elsewhere on their body.

The exact cause of psoriasis is not known, but it involves the immune system overreacting. It typically runs in families, so it’s likely there’s a genetic link.

Anyone can develop seborrheic dermatitis, too. However, research indicates that men develop it more often than women.

Factors that may play a role in developing seborrheic dermatitis include:

  • a family history of seborrheic dermatitis
  • oily skin
  • neurological conditions including Parkinson’s or epilepsy
  • stress
  • lack of sleep

Treatment may depend on the severity of your condition. Everyone responds differently to medication, so it may take a few tries to find the right solution for you.

People of color, such as people with Black and Indigenous, may require a different treatment approach that takes into account differences in hair texture and hair washing frequency.

For some people, dandruff clears up on its own. Over-the-counter (OTC) shampoos and medication are usually enough to improve flaking and soothe itching. If not, you can talk with a doctor about prescription-strength products.

In babies, cradle cap doesn’t always require treatment. It generally resolves well before their first birthday. In the meantime, use a mild baby shampoo. Also, massage the scalp gently using a very soft brush. Being gentle with their scalp is important because breaking the skin can lead to infection. If you’re concerned about your baby’s scalp, talk with their pediatrician.

Learn more: Seborrheic Dermatitis: Best Shampoos for Treating Your Scalp

Psoriasis of the scalp may be harder to treat. Topical corticosteroids may help reduce inflammation and slow the growth of skin cells.

Light therapy can also be used to treat psoriasis. Systemic treatment may be beneficial for stubborn psoriasis. This may involve oral treatments or injectable medications. It may take a combination of treatments to get psoriasis to the point that it’s well managed.

If you have a mild case of flaky skin on your scalp, OTC dandruff products may help. If they do not, have a doctor take a look. Also, see a doctor if you have undiagnosed patches of skin that look abnormal in other places on your body.

They will likely be able to tell whether it’s psoriasis, seborrheic dermatitis, or a different condition just by examining your skin. If not, it might take looking at a skin sample under a microscope to confirm a diagnosis. In rare cases, a biopsy is needed.

Both seborrheic dermatitis and psoriasis are chronic, or lifelong, conditions. However, with proper diagnosis, treatment, and monitoring, you can effectively manage them.