10 Common Q&A about the Use of UV Phototherapy Treating Vitiligo

by Zhiwei Deng on July 25, 2023

Q1. What is ultraviolet phototherapy?


A: Ultraviolet phototherapy refers to the use of artificial light sources to treat various skin diseases. It is one of the commonly used treatment methods in dermatology. Currently, the clinically used ultraviolet wavelengths or treatment regimens for skin diseases include UVB (NB-UVB, 311nm ±2nm), 308nm excimer laser, UVA1 (340nm-400nm), and psoralen plus ultraviolet A (PUVA) phototherapy.

Q2. What is the principle of 308nm excimer laser treatment for vitiligo?


A: The principle of 308nm excimer laser treatment for vitiligo is as follows:


  • Induces T cell death (the underlying cause of vitiligo is the T cells present in the skin killing melanocytes).

  • Stimulates the proliferation of melanocytes (even in areas affected by vitiligo, some melanocytes remain unaffected by autoimmune damage, and 308nm ultraviolet light can stimulate their growth).

  • Promotes synthesis of more melanin by existing melanocytes.

  • Promotes the production of vitamin D3, which is closely related to the activity of melanocytes.

  • Targeted treatment with 308nm excimer laser can be used to irradiate small spots or focal patches of vitiligo to stimulate repigmentation. It can also be used for progressive vitiligo.

Q3. Are there any contraindications for ultraviolet phototherapy? Can all vitiligo patients undergo phototherapy?


A: No, some patients with comorbidities are not suitable for ultraviolet phototherapy, including systemic lupus erythematosus, dermatomyositis, xeroderma pigmentosum, Bloom syndrome, nevus of Ito, and malignant melanoma, among others. In addition, pregnant women, young children, patients with cataracts, porphyria, a history of radiation dermatitis, and those with a family history of malignant melanoma should exercise caution and consult with a doctor before proceeding with phototherapy.




Q4. Is ultraviolet phototherapy suitable for all types of vitiligo patients?


A: Yes, ultraviolet phototherapy can be used for vitiligo patients at different stages and with various patterns, including those with progressive (active) vitiligo, stable vitiligo, generalized (extensive) vitiligo, focal (localized) vitiligo, and segmental vitiligo. However, caution should be exercised in cases where vitiligo is rapidly progressing within the past 1-2 months. In such situations, phototherapy should be used with lower energy levels and in conjunction with supportive medications. It is important to discuss this matter with a healthcare professional.




Q5. How many times per week should phototherapy be administered?


A: The optimal frequency for phototherapy is usually 2-3 times per week with appropriate intervals. Daily treatment is not necessary. 

Typically, 10-20 sessions with a 308nm excimer laser device can lead to repigmentation

For Narrow band UVB and UVA1 devices, 30-50 sessions may be required to achieve noticeable results. If there is no improvement after 40 sessions or over a duration of more than 3 months, it is advisable to consider alternative treatment options.




Q6. Is the dosage of ultraviolet phototherapy the same for everyone?


A: In general, areas with thicker skin may require higher doses, while areas with thinner and more delicate skin may require lower initial doses. The appropriate dosage should be adjusted based on factors such as the phototherapy device used, individual patient characteristics, and the extent of the skin lesions. The relationship between the body part and dosage is as follows: hands and feet > limbs > trunk > face and neck. Additionally, the dosage may differ based on skin type, with slightly darker skin (Fitzpatrick skin type V) requiring less dosage compared to fair skin (Fitzpatrick skin type III). Age can also influence the dosage, with adults typically requiring higher doses compared to children and elderly individuals. As a general guideline, the initial dosage is usually set at around 70% of the minimum erythema dose (MED).



Q7. What should be done if blisters appear after the uv phototherapy?


A: In the case of blisters, phototherapy should be discontinued until the blisters heal. Cold compresses with ice packs can be applied, and if the blisters are large, a healthcare professional can perform aspiration to promote absorption. When the blisters rupture, revealing raw tissue, topical application of antibiotic ointments, burn ointments, or corticosteroid creams can be used to prevent infection and promote skin healing. Blisters that occur after phototherapy are considered superficial burns and generally do not result in scarring. By following the correct phototherapy technique, adverse reactions such as blisters can be avoided.




Q8. How is the dosage of ultraviolet phototherapy adjusted? How should the dosage be controlled for home phototherapy?


A: The initial dosage of phototherapy is usually set between 100-200mJ/cm2, depending on the intensity of the device. For the face, scalp, children, and patients prone to sunburn, the dosage may be reduced accordingly. Alternatively, the recommended starting dosage provided by the phototherapist can be followed. The dosage can be adjusted as follows:




If the redness or erythema lasts less than 24 hours, increase the dosage by 10-20%.

If the redness lasts between 24-72 hours, maintain the same dosage.

If the redness lasts more than 72 hours or blisters appear, discontinue treatment and reduce the dosage by 10-50% upon resumption.

Maximum single dosages: 1500mJ/cm2 for the face and 3000mJ/cm2 for the limbs and trunk. 

If the maximum single dosage is reached, it is recommended to consult with a doctor at a hospital to determine the next steps in the treatment strategy.



Q9. Is higher dosage of phototherapy more effective?


A: The dosage of phototherapy should follow a gradual and steady approach to achieve optimal results. The most effective response can be observed when the skin shows a faint pinkish-red reaction that lasts for 24-48 hours after irradiation. If the erythema reaction is too weak, the treatment effect may be poor. Conversely, if the erythema reaction is prolonged (over 72 hours) and accompanied by skin peeling or blistering, it may damage the treated area, and treatment should be interrupted. Therefore, moderate dosage leads to the best phototherapy outcomes.



Q10. What should be considered during the treatment? Is dietary restriction necessary?


  • Sun protection is crucial, with specific wavelengths and energy being effective for vitiligo treatment. However, exposure to a combination of "UV light + sunlight" can put pressure on the skin, leading to the expansion or increased occurrence of white patches, known as the "isomorphic response."


  • Avoid consuming photosensitive foods and medications (including lettuce, celery, mango, pineapple, and drugs such as sulfonamides, tetracyclines, griseofulvin, Fangfeng, Shashen, Baizhi, and Buguzhi) to prevent excessive erythema reactions after irradiation.

  • During the break between phototherapy sessions, it is recommended to use moisturizers to prevent skin dryness and associated discomfort.


  • Protect the eyes and private areas as ultraviolet light penetrates the skin to a depth of no more than 1mm, and a layer of thick paper or clothing can provide sufficient protection.

  • Additionally, individuals with vitiligo can maintain a balanced diet and do not need to restrict themselves blindly.




References: "Expert Consensus on Narrowband Medium-Wave Ultraviolet Home Phototherapy" and "Consensus on the Diagnosis and Treatment of Vitiligo (2021 Edition)."