Psoriasis: How Light Therapy Helps

Under normal conditions, your skin grows from the inside out in layers of cells. The outermost layer has the oldest cells. When the oldest cells die, they flake off and newer cells take their place.

Sometimes the older cells stay on the surface, giving your skin a dull look. Using an exfoliation tool like a loofa sponge while washing can remove these dead cells to reveal the healthy new cells underneath.

With psoriasis, the skin growth rate is accelerated. The topmost cells flake off before they have fully aged and died, and the cells underneath rise to the surface before they are mature enough. This causes raised red and flaky patches of skin. These patches can appear anywhere on the body, but they are most common on the elbows, knees, scalp, and face.

Causes of Psoriasis

Psoriasis is an autoimmune disease, meaning the immune system attacks the skin-producing cells causing them to malfunction. The disease is not contagious, and the exact cause for the autoimmune response is unknown.

What is known is that the disease most often occurs in adulthood, but can occur in children as well.


Psoriasis is usually treated with topical creams or ointments designed to reduce the appearance of the patches. A doctor might also prescribe oral steroids, or immunosuppressing drugs to prevent the immune system from attacking the skin cells.

UV light therapy, or phototherapy, is another treatment for psoriasis.


Phototherapy uses UVA and UVB light waves to slow the growth of skin cells. A doctor might prescribe UVA or UVB only, or a combination of both light waves. There are several ways to administer phototherapy.

UV Lamps

UV Lamps look like a regular table lamp, but they have special bulbs that emit UVB light. You can purchase a UV lamp for home use, or go to a clinic that specializes in UV light therapy.

Tanning Beds

Tanning beds emit UVA light. As with the UV Lamps, you can purchase your own tanning bed for home use, or go to a facility that has tanning beds.

Direct Sunlight

Direct sunlight has both UVA and UVB rays, as well as other rays along the UV spectrum. This method is the cheapest and most convenient one, since sunlight is available nearly everywhere.

Risks and Problems

UVB Light

UVB light is the most effective on psoriasis but it is also more likely to cause sunburn and skin irritation. Some psoriasis drugs also cause sensitivity to sunlight, which can increase your chance of burning if you combine those therapies with UVB therapy. Patients who use UVB light therapy must follow the doctor’s instructions to the letter and have regular checkups. Patients who are unable to do this should avoid UVB therapy.

UVA Light

UVA light is not as effective as UVB, but it also carries a lower risk for burning. However, UVA only works if you use it with a medication called Psoralen. UVA treatments can cause nausea and mild skin irritation. Patients who are allergic to Psoralen should not try UVA treatments.

Direct Sunlight

Direct sunlight contains both UVA and UVB but, because it also contains other UV rays, there is a risk of burning. Prolonged exposure to direct sunlight can also increase your risk for skin damage and skin cancer. Additionally, it’s also not possible to control the amount of UV light that you are exposed to and some regions get very little UV light during certain times of year.

Tanning Beds

Although tanning beds contain both UVA and UVB, the American Academy of Dermatology does not recommend their use because not all machines are calibrated the same. It’s not possible to control the amount of UV exposure, or to determine the optimum length of each session. Also, as with sunlight, prolonged exposure to tanning beds can increase your risk of skin damage and skin cancer.

If you are interested in using phototherapy to treat your psoriasis, consult with your physician to determine which therapy is right for you.

Have specific questions?

All Article Categories

Before & After Photos

Suggested Doctors

Recently Asked Questions