Phototherapy, or light therapy, can help reduce the symptoms of psoriasis. Home phototherapy products can be safe and effective for people with psoriasis if they follow a doctor’s instructions on use.

Psoriasis is an autoimmune disease that causes a person’s immune system to become oversensitive and attack healthy skin cells. The attacked cells reproduce more rapidly than usual and form a rash of thick, itchy, and inflamed plaques on the skin. These plaques usually have a flaky crust on top.

A person can visit an outpatient clinic for a phototherapy appointment, or a doctor can prescribe a home phototherapy unit. Research indicates that home phototherapy may offer similar results to hospital-based treatments in people with psoriasis.

This article explains how phototherapy works, the different types of home phototherapy, and possible side effects.

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Phototherapy uses UV light to reduce swelling and slow the excessive skin cell production that psoriasis causes. UV light is invisible to the naked eye and penetrates the skin.

There are two types of UV light:


This kind of light can penetrate the skin deeper than UVB. A person receiving treatment with UVA light must sensitize their skin with a plant-derived chemical called psoralen to make this treatment effective.


UVB light penetrates the outer layers of the skin and can cause sunburn. Phototherapy using UVB light is effective on its own, without any chemicals.

Most home phototherapy units use narrow-band UVB rays. These rays penetrate the top layers of the skin, interfering with cellular DNA and effectively slowing the rate of reproduction.

A doctor will determine how long a person with psoriasis needs to spend using the light therapy box, taking into account skin type, underlying medical conditions, and any medications a person is currently taking. All these factors may affect the skin’s reaction to UVB light.

Learn more about phototherapy for psoriasis here.

Phototherapy for psoriasis can often cause sunburn reactions. In rare cases, it can also lead to blisters developing.

One 2019 study suggested that people who used home phototherapy experienced severe erythema, a skin reaction that produces a rash, more frequently than people receiving treatment at a hospital. However, blistering was more common among those receiving hospital-based treatment.

UV light exposure can also increase the risk of skin cancer, so it is important to follow a doctor’s instructions and attend regular skin examinations when using phototherapy.

Learn about UV light and how to tan safely here.

The size of the equipment needed to treat psoriasis with phototherapy depends on how much skin is affected.

Small, handheld light boxes can target specific areas of the body. These may be more appropriate for home use.

However, if psoriasis rashes cover large areas of the body, a doctor may ask the person to come to a clinic and stand in a walk-in cabin. These cabins are similar in size and appearance to a tanning booth.

Phototherapy does not cure psoriasis, but it can reduce the severity of symptoms.

According to the Psoriasis and Psoriatic Arthritis Alliance, phototherapy can clear the skin completely in some cases. In others, it may just reduce the appearance of psoriasis plaques. Doctors only recommend phototherapy if other treatments, such as topical steroid creams, have failed to improve a person’s symptoms.

A 2019 study compared the results of home phototherapy treatments with hospital-based ones. Researchers used the Psoriasis Area and Severity Index (PASI), which measures the intensity and extent of an outbreak, as a baseline. Their results indicated that 40.7% of those receiving home treatment recorded a PASI score of 75 after 46 treatments, compared with 41.7% of people receiving treatment at the hospital. A PASI score of 75 equates to a 75% reduction in symptoms.

The study also indicated that people were generally happier with the treatment when receiving it at home.

Phototherapy on dark skin

Research on the effectiveness of phototherapy across skin tones has been limited, but studies are currently underway. According to the National Psoriasis Foundation, phototherapy can be highly effective in reducing the symptoms of psoriasis for people with dark skin, who often have thicker skin lesions.

However, People of Color may find that phototherapy can leave their skin with a patchy appearance. This is because the treatment can further emphasize the hyper or hypopigmentation that psoriasis can cause. People who wish to reduce the likelihood of this happening can do so by seeking light therapy treatment as soon as possible, before the condition might worsen.

A person receiving phototherapy usually has three sessions per week for between 4 weeks and 3 months. Research suggests that receiving phototherapy more than three times per week provides little benefit while exposing the person to an increased risk of side effects, such as rashes.

Some people may do only two sessions per week. According to a study in the Journal of the American Academy of Dermatology, people who received two phototherapy sessions per week saw their psoriasis symptoms clear in 88 days on average, compared with 58 days for those who had three per week.

After the initial treatment period, a doctor may recommend ongoing weekly treatments to help keep the skin clear.

Home phototherapy units reduce the need to attend a clinic or doctor’s office, but doctors recommend that people still have frequent psoriasis checkups.

A doctor will explain how a person should use the phototherapy unit at home. People will need to follow their instructions carefully, as UV rays can damage the skin, causing premature aging, sunburn, and skin cancers.

Some doctors will start phototherapy in a hospital setting before recommending that a person continue the treatment at home. The doctor will explain the importance of protecting sensitive areas of the body, such as the eyes and genitals, and when to apply moisturizers. They will also explain how to position the light box to target the appropriate area and how far away from the unit a person should stand.

The doctor will assess a person’s medical history and note any medications they are taking, including supplements and herbs. Based on the person’s skin type, they will recommend an initial dose for the first few treatments, building up gradually from there.

A person must allow at least a 24-hour interval between sessions and will need to reduce their exposure time if they regularly miss treatments.

The cost of a phototherapy kit will vary depending on the type. A doctor can help a person determine which device will be most effective for them. Phototherapy products vary in size from small, handheld devices to full-body surround cabinets.

Medicare insurance may cover the cost if the device is medically necessary. This will usually fall under Medicare Part B since it counts as durable medical equipment.

Learn more about Medicare Part B here.

Phototherapy is a safe and effective treatment for the symptoms of psoriasis. It works by shining UV light onto a person’s skin. UV light alters DNA to slow down the rate of skin cell reproduction.

In some people, phototherapy can clear up skin symptoms from psoriasis entirely. In others, it may reduce the appearance of plaques.

If a person uses them correctly, home phototherapy products provide similar benefits to clinic-based treatments. A person can only get home phototherapy equipment with a doctor’s prescription.