A port wine stain is a permanent birthmark made up of abnormally dilated blood vessels in the skin. It appears at birth as a flat, pink, red, or purple patch, most often on the face or neck, and affects roughly 0.1% to 2% of newborns worldwide. Unlike many other vascular birthmarks, port wine stains do not fade on their own. They grow proportionally with the body and typically darken and thicken over time.
What Causes Port Wine Stains
Port wine stains result from a random genetic mutation that happens during fetal development. In about 80% of cases, researchers have identified a specific mutation in a gene called GNAQ, concentrated within the blood vessels of the affected skin. This mutation causes the small blood vessels (capillaries) near the skin’s surface to stay permanently dilated, pooling more blood in that area and creating the visible discoloration.
Because the mutation is somatic, meaning it occurs spontaneously in a small number of cells during development rather than being inherited, port wine stains are not passed from parent to child. They are not caused by anything that happened during pregnancy, and there is no way to prevent them.
How Port Wine Stains Look and Feel
At birth, a port wine stain is flat and smooth, ranging in color from pale pink to deep red or purple. It has well-defined borders and usually appears on one side of the face or neck, though it can occur anywhere on the body. The skin surface feels the same as surrounding skin in infancy, with no raised texture or bumps.
One of the most important things to understand is that port wine stains change over the course of a lifetime. The color gradually deepens from pink to dark red or purple, and the skin can thicken. In a large study of patients, about 20% developed raised, thickened, or nodular skin within their birthmark. This thickening was rare before age 20 (only 7% of cases) but common after 50, when 71% of patients showed some degree of tissue buildup. The median age for thickening to begin was around 31, with nodular bumps typically appearing closer to age 39.
Port Wine Stain vs. Salmon Patch
Many parents confuse port wine stains with salmon patches, which are the most common vascular birthmarks in newborns. The differences are straightforward. A salmon patch is a pale pink mark with blurry, poorly defined edges, commonly found on the back of the neck (“stork bite”), between the eyebrows (“angel’s kiss”), or on the eyelids. Salmon patches become more noticeable when a baby cries or gets warm, and they usually fade within the first year of life.
A port wine stain, by contrast, is darker, has sharp borders, and does not fade with time. If a birthmark is still clearly present after the first birthday and has well-defined edges, it is more likely a port wine stain.
When Location Matters
Most port wine stains are purely cosmetic. However, when a port wine stain covers the upper portion of the face, particularly the forehead and the area around the eye, there is a meaningful risk of a condition called Sturge-Weber syndrome. This syndrome involves abnormal blood vessels not just on the skin, but also in the eye and brain on the same side.
In one study of facial port wine stains, 26% of patients with involvement of the upper face (the forehead-to-eye region, known as the V1 area of the trigeminal nerve) had neurological or eye complications. When the birthmark covered the entire upper face, the risk jumped to 78%. Glaucoma and seizures were the most common complications. Babies with port wine stains in this area are typically evaluated with brain imaging and regular eye exams to catch any involvement early.
Port wine stains that are limited to the lower cheek, jaw, or body carry a much lower risk of these complications.
Laser Treatment
The standard treatment for port wine stains is pulsed dye laser therapy, which targets the dilated blood vessels with light energy to break them down. The laser selectively heats the abnormal vessels while leaving surrounding skin mostly intact. Multiple sessions are needed, spaced weeks to months apart.
A large 20-year study of 974 children found that the overall success rate (defined as achieving at least 51% clearance) was about 65%. Results improved with more sessions: 41% of patients responded well after one treatment, rising to 84% after four sessions. Infants had a success rate of 71%, supporting the common recommendation to begin treatment early, when the skin is thinner and the vessels are smaller.
Complete clearance is possible but not guaranteed. One of the frustrating realities of laser treatment is that blood vessels can reform and refill over time, leading to partial recurrence. Many patients require periodic maintenance sessions throughout their lives. Early research into combining laser therapy with a topical medication that suppresses vessel regrowth has shown promising results. In a clinical trial, the combination reduced visible vessels significantly more than laser alone, though this approach is not yet widely available.
Among patients treated with laser, about 60% report being satisfied with their results and would recommend the treatment to others.
Psychosocial Impact
The emotional weight of living with a visible facial birthmark is well documented. In surveys, 75% of people with port wine stains said the mark negatively influenced their life, and 61% believed their life would meaningfully change if the birthmark could be removed. The quality-of-life impact is comparable to that of other chronic visible skin conditions like rosacea and vitiligo.
Children with port wine stains tend to cope relatively well, but the social impact increases significantly in adolescence and adulthood. Adults report difficulty in social interactions, describe being treated differently by others, and feel the birthmark affects their ability to attract romantic partners. The psychological burden is heaviest when the birthmark has thickened or developed nodules, with untreated hypertrophic port wine stains perceived by others as roughly equivalent in severity to losing vision in one eye. Laser treatment, even when incomplete, significantly improves how others perceive the birthmark and how patients feel about their appearance.
Patients with facial port wine stains were willing to spend, on average, 12% of their monthly income and over an hour a day on a hypothetical cure. Those numbers reflect just how central the birthmark becomes to a person’s daily experience and self-image.