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Phototherapy of Skin - Types, Contraindications, and Complications

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Phototherapy or light therapy has been used for centuries to treat skin lesions using artificial ultraviolet for a limited time.

Medically reviewed by

Dr. Nidhin Varghese

Published At September 1, 2022
Reviewed AtFebruary 27, 2024


Sun is the primary UV light source with many skin benefits and risks. UV light is artificially made and used in treating skin lesions. It is either used separately or in combination with other medications. Using light beams for treating lesions is known as phototherapy.

How Does Phototherapy Work?

When the immune system overreacts, the UV light targets the lesion and halts the immune reaction.

UV light also stimulates melanocytes, the skin’s pigment-producing cells

What Are the Types of Phototherapy?

There are two main types of phototherapy:

1. Ultraviolet B (UVB) - UVB includes

  • Broadband UVB: Uses light of broad range wavelengths and does not treat areas of skin folds.

  • Narrowband UVB (NB-UVB) — Uses light of narrower range wavelengths. It covers specific areas, even skin folds.

  • Excimer laser therapy.

2. Ultraviolet A (UVA) - UVA includes

  • UVA1 - Uses high wavelengths.

  • UVA2 - Uses low wavelengths.

  • Psoralen-UV-A (PUVA) - Uses UVA light and an oral medicine called psoralen that makes your skin more sensitive to light.

What Is UVB Therapy?

NB-UVB and BB-UVB: UVB light (NB-UVB and BB-UVB) damages the cell DNA and kills melanin-producing and immune cells. Narrow band-UVB is the first-line treatment for moderate-to-severe skin lesions. Narrow band is mainly replaced with broad band lights because it has high efficacy and low recurrence.

Excimer Laser Therapy: An excimer laser is a focused UVB treatment. Excimer is a combination of noble gas (Argon/Krypton/Xenon) and halogen gas (Fluoride or Chloride). Excimers are beneficial for difficult-to-treat areas like the scalp, palms, and soles. The USA approved excimer laser to treat psoriasis, vitiligo, and localized skin inflammation.

What Is UVA Therapy?

UVA destroys the blood vessels, nerves, and fibers.

UVA is further categorized into UVA1 (340–400 nm) and UVA2 (320–340 nm).

PUVA Therapy: PUVA is exposure to UVA by phototherapy or direct sunlight after administering psoralen, either oral, topical, or bath. Psoralens chemically activate DNA reversing the proliferation of blood and immune cells. It also stimulated melanin formation. PUVA is effective for several skin lesions. PUVA treatments can cause severe burns and are associated with a higher risk of skin cancer than any other form of phototherapy.

What Are the Approaches Towards Phototherapy?

Personalized Care - After a detailed evaluation, treatment is customized to the patient’s needs.

Preparing for Treatment:

  • Full-body skin examination is done to know about skin reaction to sunlight.

  • History of skin cancer of personal and family skin cancer and light-sensitive disorders.

  • Pregnancy and breastfeeding details.

  • Medications include patches, creams, herbal supplements, Retinoid, antibiotics, cancer medications.

  • Consult with an eye specialist before beginning the treatment.

Phototherapy in Dermatologist’s Office:

The area to be treated should not be covered with any clothes, and the surrounding untreated area should be covered and protected. Other safety measures include:

  • Applying sunscreen on the neck, lips, and backs of hands.

  • Wear special glasses or goggles to protect eyes from UV light.

  • Cover genitals in men; apply sunscreen for nipples and areola in women.

During phototherapy, skin gets quickly adapted to the dosage of light delivered. The dosage is continuously increased to promote faster healing, based on the skin’s response to light therapy. Since the response to every individual and every area is different, the dermatologist evaluated the treated skin the next day.

Phototherapy is usually done in a skin specialist clinic, but in cases where long-term therapy is needed, then home treatment is advised.

Phototherapy at Home:

Taking a phototherapy session will require a phototherapy machine at home.

The following steps are done in-home phototherapy.

  • Skin specialists propose a home phototherapy order form for the patient. It includes the type of therapy and the dosage.

  • In addition, a home LED blue light; tanning bed may be efficacious in treating psoriasis.

  • Less costly and more convenient for patients.

  • Do not apply lotion or moisturizer for 24 hours before treatment.

  • Wear protective goggles provided by the phototherapy machine company. If eyelids are to be treated, keep your eyes closed until the treatment is complete.

  • Cover all the areas, exposing only the lesion.

  • The company will pre-set the dosage of phototherapy.

  • Stay at a distance from the unit throughout the treatment; expose affected skin to the phototherapy light, as directed by a dermatologist.

Phototherapy Session Length:

A phototherapy session varies depending on the skin type and strength of the light. It usually lasts from a few seconds to minutes.

  • Broadband therapy needs three to five sessions each week.

  • Narrowband therapy needs two to three sessions each week.

  • PUVA therapy needs about 25 sessions over two to three months.

  • Laser therapy is usually done twice a week.

Treatments continue till clear skin is obtained. Sometimes, maintenance treatments may be required. The maintenance therapy can be done with a dermatologist or a home UV light unit.

What to Expect and Do After Phototherapy?

  • Avoid natural sunlight.

  • Clothing and sunscreen are mandatory when outdoors to avoid overexposure to UV light.

  • Psoralen can increase the risk of sunburn after PUVA treatment.

  • Protect your eyes from sun exposure for the next 24 hours after PUVA treatment to avoid cataracts.

  • Antihistamines may be prescribed to comfort the itching.

  • Redness, itching, or a burning sensation are side effects of phototherapy.

  • Phototherapy can cause dryness of the skin. Moisturize skin with a fragrance-free moisturizer at least once a day.

What All Conditions Require Phototherapy?

Phototherapy is used to treat multiple skin conditions, like:

  1. Psoriasis.

  2. Vitiligo.

  3. Eczema.

  4. Lichen planus.

  5. Cutaneous T-cell lymphoma.

  6. Itchy skin.

  7. Sclerotic conditions.

  8. Solar urticaria

  9. Atopic dermatitis

  10. Acute graft-versus-host disease.

  11. Pruritus.

  12. Atopic dermatitis.

  13. Mycosis fungoides.

  14. Polymorphous light eruption.

What Factors Increase the Risk of Complications?

  1. Sun allergy.

  2. Pregnancy or nursing.

  3. Skin cancer or lupus that requires you to avoid the sun.

  4. History of skin cancer.

  5. Liver disease.

What Are the Contraindications?

Absolute contraindications to phototherapy include:

  1. Systemic lupus erythematosus (SLE).

  2. Xeroderma pigmentosum.

  3. Porphyria

Relative contraindications to phototherapy include:

  1. History of melanoma or non-melanoma skin cancer.

  2. History of treatment with arsenic or ionizing radiation.

  3. Immunosuppression.

  4. History of treatment with anti-cancer drugs.

What are the Complications of Phototherapy?

If any of the following complications are seen after a phototherapy session, it is advised to visit a dermatologist.

  1. Flu-like symptoms like headaches or body aches, fatigue, nausea, vomiting, diarrhea, cough, sore throat, runny or stuffy nose.

  2. Burning skin.

  3. Cataracts.

  4. Headache.

  5. Fatigue.

  6. Fever, chills, any signs of infection.

  7. Redness or any discharge around the skin lesion.

  8. Development of new symptoms of discharges around the skin lesions.

  9. Severe pain, burning, or blistering of the skin.

  10. Skin lesions worsen temp.

  11. Premature aging of the skin, like wrinkles or dryness.

  12. Freckles.


Phototherapy is a handsome treatment option anyone can opt for, especially for those who need a natural treatment, unlike creams or steroids. A phototherapy is also an excellent option for children and women during pregnancy.

Frequently Asked Questions


Is Phototherapy Beneficial for the Skin?

Phototherapy is a useful therapeutic tool in dermatology. It is said to boost the level of collagen in the skin, which can lessen the appearance of wrinkles and other aging signs. Acne, eczema,  dermatitis, psoriasis, scarring, rosacea, and sun damage are other conditions treated with LED light therapy. However, you must have regular treatments to see improvements in the skin. In addition, in-office LED light therapy is more powerful than at-home devices, making it more effective.


How Long Does Phototherapy Take to Show Results?

Depending on the form of light therapy, people usually notice an improvement in two to four weeks. Each person's skin reacts differently to phototherapy, regarding how much progress they see in their psoriasis symptoms and how long those benefits last. The average time to remission is three to 12 months.


How Frequently Can You Get Phototherapy?

The type of phototherapy determines the duration of treatment: Broadband therapy requires three to five treatments per week. Narrowband therapy necessitates two to three treatments per week. PUVA treatments typically require 25 treatments spread out over two to three months.


Can I Apply Lotion During Phototherapy?

During phototherapy, do not apply lotion or moisturizer. A treatment unit may be used to treat a large area. During treatment, you can stand in this unit. Smaller units are used to treat smaller areas. A laser treatment will employ a laser light directed at a specific area.


Can Phototherapy Result in Blindness?

Prolonged blue light exposure in adults can cause retinal damage. Although retinal injury from phototherapy has not been reported, newborn eye covers are a standard precaution. Light sensitivity can be increased by PUVA treatments for the skin or photodynamic therapy for cancer. When exposed to sunlight or other bright lights, sensitivity can cause eye damage. Cataracts may develop as a result of light therapy.


Is Sunlight Better Than Phototherapy?

After accounting for isomerization efficiency and area of exposure, data revealed that sunlight is nearly 6.5 times more effective than a phototherapy unit when used at the ward geometry. Furthermore, sunlight is more effective in the winter because its intensity is lower.


Does Phototherapy for Psoriasis Darken Skin?

Phototherapy is a treatment that can cause skin darkening. If the dermatologist recommends phototherapy to treat one's psoriasis, they will stand in front of a light box twice weekly. The light from such treatments can cause tan or darkening of the treated skin.


Can Phototherapy Worsen Eczema?

Phototherapy is used to combat mild to severe atopic eczema, also known as atopic dermatitis. If sunlight is a trigger for your eczema, this treatment option may not be suitable for you as it may worsen your eczema. It is also not advised if you have a family history of skin cancer.


Which Light Is Best for Phototherapy?

Phototherapy destroys cancer cells by using either ultraviolet A (UVA) or ultraviolet B (UVB) light (UVB). Both types of UV light are delivered via fluorescent lamps specially calibrated to maximize treatment efficacy while minimizing the risk of burns. Blue-green light is the most effective for phototherapy because it penetrates the skin and is absorbed by bilirubin to produce the photochemical effect.


What Are the Contraindications of Phototherapy?

The following are the absolute contraindications of phototherapy:
-Systemic lupus erythematosus (SLE). 
-Xeroderma pigmentosum. 
Relative contraindications to phototherapy include:
-History of melanoma or non-melanoma skin cancer. 
-History of treatment with arsenic or ionizing radiation.
-History of treatment with anti-cancer drugs.
Dr. Nidhin Varghese
Dr. Nidhin Varghese



phototherapyexcimer lasernarrow band ultraviolet light
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