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Psoriasis treatment: Phototherapy

effects of laser treatment on nail psoriasis
Laser treatment for nail psoriasis: Six treatments, which were given once a month with a pulsed dye laser, lead to noticeably less nail discoloration, crumbling, and pitting.
Phototherapy is a treatment that uses certain types of light. If you are interested in using phototherapy, be sure to ask a dermatologist about this treatment. Dermatologists are the doctors who receive the most training in phototherapy.

Why do dermatologists prescribe phototherapy for psoriasis? 

This treatment can: 

  • Slow rapidly growing skin cells

  • Suppress an overly active immune system

  • Reduce inflammation and allow the skin to heal

  • Reduce or eliminate the itch 

Safety and effectiveness

Most people who have psoriasis can use a type of phototherapy called narrowband UVB. Dermatologists prescribe this for children, women who are pregnant or breastfeeding, and people who have a weakened immune system or an ongoing infection.  The excimer laser provides a type of narrowband UVB phototherapy that can safely treat children and adults who have psoriasis on the scalp, ears, armpits, groin, or buttocks. This laser can also safely treat areas like the elbows and knees.

Salicylic acid warning

Going for phototherapy treatment? Don’t apply your salicylic acid (used to treat acne and psoriasis scale) beforehand. When applied to the skin before phototherapy, salicylic acid can make UVB phototherapy less effective.

unlocking car door

Research shows that different types of phototherapy can effectively treat:

  • Small areas of stubborn, thick plaque psoriasis

  • Palmoplantar (on hands and feet) psoriasis that you’ve had for a long time

  • Plaque psoriasis that covers a large amount of skin

  • Nail psoriasis

  • Scalp psoriasis

Can anyone who has psoriasis use phototherapy?

While dermatologists prescribe phototherapy for many people, it is not recommended for anyone who has: 

  • Had a melanoma or any other type of skin cancer

  • A medical condition that makes you more likely to develop skin cancer, such as Gorlin syndrome or xeroderma pigmentosum

  • A medical condition that makes you sensitive to UV light, such as lupus or porphyria

  • To take medicine that makes them more sensitive to UV light, such as some antibiotics, diuretics, and antifungals 

How to use

Phototherapy is usually given at a psoriasis treatment center or hospital. To be effective, most patients need two or three phototherapy treatments a week. This means that you must go to the treatment center or hospital two or three times a week for several weeks. In some cases, you may need to go five times a week.  There are different types of phototherapy. The most common types that dermatologists prescribe are:

  • UVB light (narrowband or broadband): You stand in a light box or a light source is passed over your skin.

  • Laser treatment: The dermatologist uses a laser to deliver high doses of light only to the psoriasis.

  • PUVA bath: You soak in water that contains a medicine called psoralen (sor-ah-len). This medicine makes the skin more sensitive to UV light. After soaking, you wait for a specified time and then receive UVA light treatment.

  • PUVA with pills: You take psoralen pills, wait about 45 to 60 minutes, and then receive UVA light treatment.

  • At-home treatment: If phototherapy works for you, your dermatologist may prescribe an at-home light box or handheld device for you to use. At-home treatment can be helpful for treating flares and keeping psoriasis under control. 

Possible side effects

While phototherapy is considered safe, medical treatments carry possible side effects. With phototherapy, the possible side effects that can happen immediately after treatment include:

  • Sunburn-like reaction (red or tender skin)

  • Mild stinging or burning

  • Dark spots on the skin (more common in people who have a medium to dark complexion)

  • Itching

  • Blisters (rare)

  • Burn (rare)

After each treatment, your skin should be a little red or pink. This is desirable and not considered a side effect.

Possible long-term side effects include: 

  • Freckles

  • Early skin aging (age spots, wrinkles, loose skin)

  • Increased risk of developing skin cancer

Under a dermatologist’s care, these long-term side effects can be managed. 

What to discuss with your dermatologist

If you use phototherapy to treat psoriasis, your dermatologist will check you after you have had a certain number of treatments, usually four to six in the beginning. These checkups are essential, so be sure to keep all of your appointments. 

During these appointments with your dermatologist, you should tell your dermatologist if you have:

  • Any side effects 

  • Worsening psoriasis after phototherapy

  • Missed more than two appointments

If you miss appointments, it’s unlikely that phototherapy will be helpful for you. Research shows that patients see steady improvement only when they receive phototherapy two to five times per week.

Image 1: Photograph used with permission of the Journal of the American Academy of Dermatology. J Am Acad Dermatol. 2012;66:807-12.

Image 2: Getty Images

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Anderson KL, Feldman SR. “A guide to prescribing home phototherapy for patients with psoriasis: The appropriate patient, the type of unit, the treatment regimen, and the potential obstacles.” J Am Acad Dermatol. 2015;72(5):868-78.

Lapolla W, Yentzer BA, et al. “A review of phototherapy protocols for psoriasis treatment.” J Am Acad Dermatol. 2011;64(5):936-49.

Lim HW, Silpa-archa N, et al. “Phototherapy in dermatology: A call for action.” J Am Acad Dermatol. 2015;72(6):1078-80.

Menter A, Korman NJ, et al. “Guidelines of care for the management of psoriasis and psoriatic arthritis: section 3. Guidelines of care for the management and treatment of psoriasis with topical therapies.” J Am Acad Dermatol 2009;60:643-59.)

Menter A, Korman NJ, et al. “Guidelines of care for the management of psoriasis and psoriatic arthritis: section 5. Guidelines of care for the treatment of psoriasis with phototherapy and photochemotherapy.” J Am Acad Dermatol 2010;62:114-35.

Menter A, Korman NJ, et al. “Guidelines of care for the management of psoriasis and psoriatic arthritis: section 6. Guidelines of care for the treatment of psoriasis and psoriatic arthritis: case-based presentations and evidence-based conclusions.” J Am Acad Dermatol. 2011;65(1):137-74.

Mudigonda T, Dabade TS, et al. “A review of targeted ultraviolet B phototherapy for psoriasis.” J Am Acad Dermatol. 2012;66(4):664-72.

Treewittayapoom C, Singvahanont P, et al. “The effect of different pulse durations in the treatment of nail psoriasis with 595-nm pulsed dye laser: a randomized, double-blind, intrapatient left-to-right study.” J Am Acad Dermatol. 2012;66(5):807-12.