Port-wine Stain - Causes and Symptoms

What causes a port-wine stain?

A port-wine stain is also called a naevus flammeus or, more commonly, a firemark. It is almost always a birthmark. It is caused by abnormal development of tiny blood vessels.

  • Usually port-wine stains are found from birth in newborn babies. They are formed because the tiny blood vessels (capillaries) in the skin are too big (dilated).
  • Normally we have microscopic nerves that keep the blood vessels small (constricted) most of the time. This keeps skin cool and pale usually.
  • In port-wine stains the nerves that control the blood vessels don't work properly, so they are permanently dilated. The result is that the skin looks red when it shouldn't.
  • Usually the redness is in a patch on the face, neck, scalp or upper chest.

How common are port-wine stains and do they run in families?

  • Generally speaking, port-wine stains are just random events and there isn't anyone else in the family who has one.
  • About 1 in 300 newborns have a port-wine stain. That is fairly common. In rare cases it can develop in early childhood. But you might not see too many people with them, because some patches might be small and barely noticeable. Some people might have had them treated at a young age and the red colour has faded away, or they may be using camouflage products to cover them up.

What are the symptoms of a port-wine stain?

  • Generally the only symptom of a port-wine stain is the appearance.
  • They are not painful or itchy.
  • A port-wine stain is treated in case the appearance of it could upset the child as they grow up.

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Dr Oliver Starr
Peer Reviewer:
Dr Helen Huins
Document ID:
4517 (v41)
Last Checked:
15 May 2017
Next Review:
29 June 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.