What causes a port-wine stain?

This birthmark, also called a capillary malformation, is not caused by an injury, food, or something a parent did during pregnancy. It may be pink, red, or purple and often appears on one side of the face or another body area. The colour can deepen and the surface may become thicker or more textured over time. Most features are limited to the skin, but a facial mark near the forehead, eyelid, or scalp may warrant assessment for associated eye or neurological concerns.

Arrange an evaluation for a new or longstanding mark if its location, colour, or texture has changed, or if the diagnosis is uncertain. Protect exposed skin from sun because tanning can increase contrast with the birthmark. Do not use bleaching products or attempt to remove it at home. If treatment is wanted, a dermatologist may discuss [Pulsed Dye Laser Treatment](/treatments/laser-and-energy/pulsed-dye-laser-treatment/), including expected sessions, skin type considerations, temporary redness, and aftercare.

Seek prompt medical review if the mark bleeds without clear injury, develops an ulcer, becomes suddenly painful, or changes quickly. An infant with a facial mark involving the eyelid or forehead should be assessed early so vision and other relevant concerns can be considered. Urgent care is appropriate for sudden vision change, weakness, seizure, or severe headache.

Does the mark have features of a capillary malformation? Does its facial location call for an eye or neurological assessment? If laser treatment is suitable, what colour change, recovery, and follow-up should I expect?