That red, itchy rash on your scalp that has flaky scales could be seborrheic dermatitis, or seborrhea. It's a common skin disease that looks similar to psoriasis, eczema, or an allergic reaction. And it can appear on your body as well as your scalp.

Causes

We don't know what exactly causes seborrheic dermatitis. It seems to be a combination of things, including:

  • Stress
  • Your genes
  • A yeast that normally lives on skin
  • Certain medical conditions and medicines
  • Cold, dry weather

Symptoms

Dandruff and cradle cap are common names for seborrheic dermatitis. Babies 3 months and younger often get cradle cap: crusty yellow or brown scales on their scalp. It usually goes away before they're a year old, although it can come back when they reach puberty.

You might get seborrheic dermatitis on your face, especially around your nose, on your eyelids, or behind your ears. It can show up on your body, too:

  • In the middle part of the chest
  • Around the navel
  • On buttocks
  • In skin folds under arms and on legs
  • In the groin
  • Below breasts