Top 3 Most Affected Body Parts
Psoriasis develops because people with psoriasis have an overactive immune system, leading to chronic inflammation. This inflammation triggers the production of new skin cells more quickly than older skin cells can die off and be shed from the skin naturally. The new skin cells push the older cells up to the surface of the skin, where they build up in the form of skin lesions. The most common type of these skin lesions in people with psoriasis are called plaques.
Plaque psoriasis can develop anywhere on a person’s body, but may often form on the scalp, elbows, knees, lower back, hands, feet, nails, genitals, and skin folds. A person with psoriasis may have plaques just in one area of the body, or they may develop in multiple locations.
In our recent Psoriasis In America survey, we asked people what areas of their body were affected by psoriasis at the time they were diagnosed. The most frequently affected parts of the body, that were affected in over 50% of those who responded to the survey were:
- Scalp 62%
- Arms and/or elbows 58%
- Legs and/or knees 55%
Psoriasis symptoms can occur anywhere on a person’s scalp, and the back of the head is a common place for plaques to develop. There may be just one patch on the scalp or multiple patches in different places. In some people, plaques might extend outside the area of the scalp that is covered in hair. For example, they might occur on the forehead at the edge of the person’s hairline, around the ear area, or on the back of the neck at the bottom of the hairline.
Plaques on the scalp are usually covered by hair and not very visible to others, but the scale on top of the plaque can tend to flake and fall off in small pieces. Flare-ups of scalp psoriasis and dandruff-like flaking can have different causes for different people, but some common triggers are cold weather, dry air, and experiencing stress.
However, treating psoriasis on the scalp can be more challenging than treating it on other parts of the body because the hair can make it difficult for treatments to reach the affected area on the scalp. For many people with very mild scalp psoriasis, over-the-counter topical medicines can be helpful. Topical medicines are applied directly to the affected areas on the skin. Coal tar is a non-prescription treatment that can help to reduce the growth of skin cells that cause the plaques. Another option is salicylic acid, which can help to lift the scales on psoriasis plaques off of the affected skin.
Medicated shampoos are another option for treating scalp psoriasis. Some of them contain coal tar, while others contain different kinds of active ingredients. These types of shampoos are generally rubbed into the scalp and left to sit for a period of time so that the treatment can penetrate the scalp through the hair.
Consult a healthcare provider before starting these treatments for scalp psoriasis, because they can cause side effects for some people.
Arms/Elbows and Legs/Knees:
The arms/elbows and legs/knees are also very common sites for plaque psoriasis symptoms. In other studies, about half of people with psoriasis report having symptoms on their elbows, and around one-third of people have symptoms on their knees. Plaques in these locations can tend to lead to painful cracks or “fissures” because the joints move so much during normal activities, which ruptures the plaques.
Plaque psoriasis on the part of the arm or leg that is not the joint (extensor surface) or flexural surface will be the more common plaque presentation. It is also possible to have guttate, or pustular psoriasis on the arms and legs, and these skin presentations can occur at the same time as plaques. Treatment options for psoriasis on the arms and legs include light therapy, topical treatments, systemic medications, and therapeutic biologics.
There is a wide range of treatment options available for people with psoriasis symptoms on the elbows and knees. Because the plaques on the knees and elbows can be especially dry and prone to painful cracking, some people find that special, thick moisturizers (emollients) can help. While moisturizers will not treat the cause of the psoriasis plaques, many people find that they offer some relief and help to reduce dryness, cracking and bleeding.