Phototherapy and Home Phototherapy for Psoriasis
69. How should psoriasis patients conduct maintenance treatment after achieving clinical remission through phototherapy?
Answer: Maintenance treatment can be initiated when psoriasis lesions are basically resolved (>95%). A commonly used maintenance regimen is as follows:
Use the final treatment dose once a week for 4 weeks.
Then reduce the dose to 75% of the final dose, administering it once every two weeks for 4 weeks.
Further reduce the dose to 50% of the final dose, administering it once every two weeks for 4 weeks, after which treatment can be stopped
70. Can maintenance treatment reduce recurrence?
Answer: Maintenance treatment can be performed after lesion clearance to extend the remission period and reduce recurrence. A 1-year follow-up of patients with plaque psoriasis whose lesions resolved after NB-UVB phototherapy showed that 57% of patients in the maintenance treatment group remained in remission, compared to only 17% of patients who did not receive maintenance phototherapy [¹⁵]. This confirms that NB-UVB can be used for maintenance treatment and can reduce recurrence. Currently, multiple domestic and international psoriasis treatment guidelines recommend implementing maintenance treatment for psoriasis phototherapy, often enhanced by uv phototherapy protocols.
71. How to discontinue phototherapy based on the improvement of the condition?
Answer: Phototherapy can be considered for discontinuation under the following three circumstances:(1) If lesions are basically resolved after phototherapy, start maintenance treatment; phototherapy can be discontinued after the completion of maintenance treatment.(2) If phototherapy is effective in the early stage but lesion improvement becomes insignificant after a period of treatment (indicating the plateau phase), phototherapy can be suspended for 2–3 months before resuming.(3) If there is no significant improvement in lesions after 3–6 consecutive months of phototherapy, the patient may be insensitive to phototherapy. In this case, switch to another treatment regimen or combine it with other treatments [¹]. Alternatives like red light therapy for eczema might be explored for persistent symptoms.
72. Under what circumstances do psoriasis patients need to suspend or discontinue phototherapy?
Answer: A doctor's assessment is required to determine whether to discontinue phototherapy. Generally, phototherapy can be considered for discontinuation under the following circumstances:(1) Severe adverse reactions occur, such as erythema and blisters. This is more common in photosensitive patients or those who conceal the time of the previous treatment and post-treatment reactions, leading to excessive dosing in the current treatment.(2) The treatment reaches a plateau phase-i.e., phototherapy is effective in the early stage, but subsequent dose increases do not significantly promote lesion resolution.(3) The patient is insensitive to phototherapy, with no significant improvement in lesions after 3–6 consecutive months of treatment.
73. What are the adverse reactions of home phototherapy for psoriasis?
Answer: The adverse reactions of home phototherapy are the same as those of hospital-based phototherapy. Excessive doses can cause acute adverse reactions such as erythema and blisters, while long-term irradiation may lead to dry skin and hyperpigmentation. Additionally, long-term phototherapy may cause skin photoaging and increase the risk of skin tumors. However, current studies have not confirmed that NB-UVB increases the risk of skin tumors [¹, ¹²]. For facial involvement, red light therapy for face can sometimes mitigate mild irritation when used adjunctively.
74. What are the effects of irradiating normal skin during phototherapy?
Answer: For small-area lesions, local phototherapy is recommended. For patients with large-area lesions, whole-body phototherapy can be used, which will inevitably irradiate normal skin. Irradiation of normal skin may cause discomfort such as erythema, pruritus, and hyperpigmentation. There is no need to panic-most cases of erythema and pruritus will resolve within 24–48 hours. If symptoms such as erythema, burning pain, or blisters occur, consult a professional for guidance on management. In such scenarios, led face light therapy may offer gentle support for affected facial skin.
75. How to alleviate dry skin and aggravated pruritus experienced by some patients after phototherapy?
Answer: Dry skin and pruritus after phototherapy can be relieved through the following methods:
(1) Use penetration-enhancing oil before phototherapy. This oil facilitates light penetration to improve phototherapy efficacy and has a mild moisturizing effect, which can prevent phototherapy-induced dry skin. However, it should be applied thinly-excessive application will instead reduce phototherapy efficacy.(2) Moisturize the skin promptly after phototherapy to alleviate dryness and pruritus. Additionally, psoriasis patients should use moisturizers regularly in daily life, as this is the basic skin care measure for psoriasis.
76. What causes aggravated lesions after phototherapy?
Answer: A small number of psoriasis patients experience aggravated lesions after phototherapy, which may indicate photosensitive psoriasis. Such patients need to undergo a photosensitivity test for diagnosis. If photosensitive psoriasis is confirmed, phototherapy should be discontinued, and an alternative treatment regimen should be adopted. In addition, unscientific phototherapy regimens can also worsen the condition-for example, phototherapy for progressive erythrodermic psoriasis may irritate the skin and exacerbate symptoms. Therefore, ultraviolet phototherapy must be performed under the guidance of a professional doctor, with uv phototherapy being a core modality.
77. How to manage skin burning, even erythema or blisters, caused by excessive single-dose irradiation?
Answer: If severe adverse reactions such as erythema or blisters occur after phototherapy, first suspend phototherapy. For mild erythema without other discomfort, observe the condition without intervention. Resume phototherapy only after symptoms completely resolve, and reduce the dose by 20% compared to the previous session. If erythema is accompanied by pain, burning, or even blisters, first apply local cold compresses or topical glucocorticoid cream (e.g., halometasone). If symptoms are severe or the above measures are ineffective, seek medical attention promptly.
78. How to adjust the treatment dose after interrupting home phototherapy?
Answer: Home phototherapy is convenient and flexible, allowing patients to arrange treatment time according to their own schedules. Most patients can adhere to treatment, and interruptions are rare. If treatment must be suspended due to special reasons, adjust the dose when resuming treatment as follows:
Maintain the original dose if the interruption lasts 4–7 days.
Reduce the dose to 75% of the original dose if the interruption lasts 8–14 days.
Reduce the dose to 50% of the original dose if the interruption lasts 15–21 days.
Restart with the initial dose if the interruption exceeds 3 weeks [¹⁴].
79. Which topical medications can be combined with home phototherapy?
Answer: Psoriasis patients can combine home phototherapy with topical medications to enhance efficacy, reduce medication dosage, and lower the cumulative phototherapy dose. Common options include:
Calcipotriene cream
Glucocorticoid cream
Retinoids (note: retinoids may cause local irritation and should be avoided on the face, periorbital area, genitals, and skin folds).
Topical medications are not recommended within 2 hours before or after phototherapy, as this may affect phototherapy efficacy.
80. When combining phototherapy with medication, should topical medication be applied before or after phototherapy?
Answer: Combining phototherapy with topical medications is common in clinical practice, as it not only improves efficacy but also reduces the cumulative ultraviolet dose. However, some medications may block ultraviolet penetration-applying them before phototherapy can reduce efficacy. Other medications may cause irritation, and the skin remains sensitive for a short period after irradiation; applying such medications immediately after phototherapy can exacerbate skin irritation. Therefore, except for photosensitizers prescribed by doctors, other topical medications should not be used within 2 hours before or after phototherapy.
81. What are the precautions for combining home phototherapy with topical moisturizers?
Answer: Precautions for combining home phototherapy with moisturizers:
In addition to regular use (twice a day) in daily life, apply moisturizer after phototherapy on treatment days to alleviate phototherapy-induced dryness and pruritus.
Additionally, a small amount of penetration-enhancing oil can be applied before phototherapy. This helps soften scales, reduce light reflection, and improve light penetration. However, it should be applied thinly-excessive application will affect phototherapy efficacy.
82. What are the precautions for combining home phototherapy with topical glucocorticoids?
Answer: Pay attention to the adverse reactions of long-term topical glucocorticoid use. Long-term application can cause skin reactions such as telangiectasia, flushing, and atrophy, as well as hirsutism. Delicate skin areas (e.g., face, armpits, groin) are more prone to these reactions and should avoid long-term use. Additionally, maintain an interval of at least 2 hours between phototherapy and topical medication application [³]. For facial concerns, red light therapy for face could be a milder adjunct.
83. What are the precautions for combining home phototherapy with topical retinoids?
Answer: Retinoids (oral or topical) can lower the ultraviolet erythema threshold, increasing the risk of adverse reactions such as erythema. Therefore, when combining home phototherapy with topical retinoids, reduce the phototherapy dose appropriately. In addition, topical retinoids may cause local irritation and should be avoided on the face, periorbital area, genitals, and skin folds [³].
84. What are the precautions for combining home phototherapy with topical calcipotriene ointment?
Answer: Combining home phototherapy with topical calcipotriene ointment not only improves efficacy but also reduces the cumulative ultraviolet dose. During combined treatment, calcipotriene ointment should be applied 2 hours after irradiation [³].
85. Which systemic medications can be combined with home phototherapy?
Answer: Common systemic medications for combined treatment include:(1) Retinoids (e.g., acitretin capsules): Retinoids can thin the thickened stratum corneum, facilitating NB-UVB penetration and reducing the cumulative irradiation dose. The two have a synergistic effect. However, retinoids can cause delayed photosensitivity, so the phototherapy dose should be reduced appropriately when used in combination.(2) Methotrexate: Combining methotrexate with phototherapy not only enhances the efficacy of methotrexate but also reduces the cumulative UVB dose.(3) Others: For severe cases unresponsive to conventional treatment, combination with biological agents may be considered [³].
86. How to combine home phototherapy with methotrexate?
Answer: There are 3 common methods for combining phototherapy with methotrexate:(1) Initiate NB-UVB irradiation after methotrexate controls inflammation.(2) Administer short-term oral methotrexate in the early stage of NB-UVB irradiation.(3) Add methotrexate for patients with poor response to NB-UVB to enhance efficacy; after achieving efficacy, discontinue methotrexate and maintain treatment with NB-UVB alone. Since methotrexate has photosensitive effects, avoid phototherapy for 48–72 hours after methotrexate administration. A common regimen is phototherapy on Mondays, Wednesdays, and Fridays, with oral methotrexate on Fridays. The latter two methods are often recommended for patients undergoing home phototherapy [³].
87. When combining oral acitretin with phototherapy, how to balance photosensitivity and efficacy?
Answer: The combination of phototherapy and acitretin aims to:
Reduce the dosage of acitretin.
Reduce the cumulative phototherapy dose.
Combined use can reduce adverse reactions of both and achieve better results. Since acitretin can cause photosensitivity, reduce the phototherapy dose appropriately when combined with ultraviolet therapy to avoid adverse reactions.
88. If a psoriasis patient receives phototherapy first or uses acitretin first, how to adjust the treatment dose?
Answer: If a patient receives phototherapy first and then adds acitretin, the first phototherapy dose after adding acitretin should be reduced by 30%–50% compared to the last dose before adding acitretin. For example, if the current irradiation dose is 1.5 J/cm², it should be adjusted to 0.75–1.05 J/cm² after adding acitretin to avoid adverse reactions. If acitretin is taken first followed by combined phototherapy, the initial phototherapy dose should be set at 50% of the minimal erythema dose (MED). Subsequent doses should be adjusted based on the skin reaction after phototherapy and the treatment interval.
89. How to combine home phototherapy with biological agents?
Answer: Combining home phototherapy with biological agents can exert a synergistic effect to enhance efficacy. Studies have shown that combining NB-UVB with TNF-α inhibitors (e.g., etanercept or adalimumab) not only accelerates onset and shortens the time to lesion resolution but also reduces the cumulative NB-UVB dose, without increasing the risk of short-term adverse reactions [¹]. Theoretically, long-term combination of phototherapy with biological agents may increase the risk of skin tumors, but no research data have confirmed this to date [¹].
90. Can home phototherapy be combined with water baths?
Answer: Yes. Water baths help remove scales, cleanse the skin, and improve blood circulation and metabolism-playing an important role in psoriasis treatment. Therefore, psoriasis patients are advised to bathe daily, with soaking baths being preferred. The water temperature should not be too high; 37–42°C is optimal. Avoid using alkaline soap or excessive rubbing with a bath towel, as this may irritate and damage the skin. Home phototherapy can be performed after bathing, once every other day. If a medicated bath is available, the effect will be better. The recommended sequence is: bathing → medicated bath → phototherapy.
91. What is the efficacy of phototherapy for palmoplantar pustular psoriasis, and how to use it in combination with topical medications?
Answer: Phototherapy is suitable for patients with contraindications to systemic treatment (e.g., severe liver dysfunction). However, phototherapy alone has limited efficacy and often needs to be combined with topical medications to improve results. Common topical medications include glucocorticoids, vitamin D₃ derivatives, retinoids, and compound preparations (e.g., calcipotriene and betamethasone ointment) [³]. Supplementary red light therapy for eczema may aid in reducing inflammation for overlapping symptoms.
92. If the single phototherapy dose has reached the maximum irradiation dose but there is still no significant improvement in lesions, can home phototherapy be continued?
Answer: This situation may indicate the phototherapy plateau phase. Home phototherapy should be suspended, and a doctor should be consulted to modify the treatment regimen.
93. How to adjust the treatment regimen when encountering the plateau phase during psoriasis treatment?
Answer: The plateau phase refers to a stage where lesions no longer resolve despite continued use of the current treatment regimen. Encountering the plateau phase means the current regimen cannot achieve better efficacy, and adjustments are needed. The specific adjustment method varies by individual: the current treatment can be suspended and replaced with another regimen, or other treatments can be added to the original regimen. The specific implementation requires a hospital visit and discussion with a doctor.
94. Is home phototherapy still effective when the condition recurs?
Answer: In general, home phototherapy remains effective for recurrent lesions. When treating recurrent lesions, phototherapy should still start with the initial dose, and the dose should be adjusted based on the skin reaction after treatment. However, psoriasis is a complex condition with multiple subtypes. Therefore, it is recommended to seek medical attention promptly after recurrence and undergo treatment under the guidance of a doctor, incorporating uv phototherapy where appropriate.
95. For psoriatic arthritis, if phototherapy basically resolves the skin lesions, can joint damage be reversed?
Answer: Phototherapy has no significant efficacy for joint damage in psoriatic arthritis. If joint damage exists, combination with other medications is required-e.g., methotrexate, leflunomide, and biological agents all have therapeutic effects on joints. For patients with polyarticular involvement, erosive disease, or severe functional limitation due to arthritis, early use of biological agents is recommended to prevent the progression of joint damage and promote rapid functional recovery. In addition, rehabilitation treatments such as exercise, physical therapy, and skill training can help improve joint function [³].
96. If psoriasis lesions in other parts of the body have resolved but only the lower legs remain affected, should phototherapy be continued?
Answer: Lesions on the lower legs are often more stubborn and slower to respond to treatment. If phototherapy is effective, it should be continued. For faster results, 308 nm UVB phototherapy can be used with higher intensity and dose, or short-term treatment combined with topical medications (e.g., high-potency glucocorticoids) can be adopted.
97. For refractory lower leg lesions, how to perform irradiation to improve efficacy?
Answer: Psoriasis lesions on the lower legs are relatively difficult to resolve, whether with topical medications or phototherapy-this may be related to the more severe inflammatory nature of lower leg psoriasis lesions. A phototherapy device that covers the entire extensor or flexor surface of both lower legs can be used to ensure optimal treatment coverage. Additionally, combining with topical medications or adding fractional laser therapy can improve phototherapy efficacy [¹⁶]. In some protocols, led face light therapy principles are adapted for localized non-facial areas to enhance comfort.
98. When new lesions appear during NB-UVB treatment for psoriasis, can phototherapy be continued?
Answer: The appearance of new lesions during treatment indicates that psoriasis is in the progressive phase. Phototherapy can still be performed during the progressive phase. Due to the recurrent nature of psoriasis itself, the emergence of new lesions during treatment is a normal phenomenon-there is no need for excessive worry, and phototherapy can be continued. However, care should be taken to avoid using an excessively high treatment dose. During home phototherapy, new lesions can also... (Note: The ending of Question 98 in the original text was incomplete; the translation is based on the provided content. For terms such as "NB-UVB" (narrowband ultraviolet B) and "MED" (minimal erythema dose), standard dermatological abbreviations are retained for consistency with international medical practice.)
When undergoing phototherapy, treatment should start with an initial dose, and the dose should be gradually increased based on the skin reaction after treatment. If there are multiple skin lesions across the body requiring different phototherapy doses, it is essential to keep detailed phototherapy records. This ensures accurate uv phototherapy administration for each lesion and prevents adverse reactions caused by incorrect dosing.
99. Some psoriasis patients do experience effects from phototherapy, but they never fully recover, and the condition recurs once phototherapy is stopped. How to address this situation?
Answer: Currently, psoriasis treatment can control the condition but cannot prevent recurrence. Recurrence after stopping treatment indicates that the condition has not been fully controlled. This phenomenon is not unique to phototherapy-other treatments may also lead to recurrence once discontinued. In such cases, it is recommended to adopt maintenance treatment or comprehensive treatment (systemic medication combined with uv phototherapy). After the condition is controlled, the dose should be gradually reduced for maintenance. Additionally, measures such as ensuring adequate sleep, avoiding overexertion, maintaining a relaxed mood, and abstaining from smoking and alcohol can help reduce psoriasis recurrence. Complementary options like red light therapy for eczema may support skin soothing in some cases.
100. Phototherapy was effective last year, but when it was reused after recurrence this year, the effect seems worse than last year. What should be done?
Answer: Analyze the possible reasons for the reduced efficacy of phototherapy to determine which of the following scenarios applies:(1) Since phototherapy was effective last year, expectations for this year are higher, leading to the perception that the expected effect is not met.(2) After phototherapy last year, skin pigmentation increased, requiring a higher dose, but the actual dose used this year has not been increased.(3) The intensity of the phototherapy device decreases after a period of use, resulting in reduced efficacy. In this case, contact the manufacturer to test the device intensity. The following adjustments can be made:(1) Increase the dose by 10%.(2) Increase the frequency of irradiation (e.g., from 2 times a week to 3 times a week).(3) Combine with other treatments, such as topical medications or traditional Chinese medicine (TCM) medicated baths, to improve efficacy.(4) Test the intensity of the phototherapy device; if the intensity is too low, replace the lamp tube. For facial areas, integrating red light therapy for face could provide additional anti-inflammatory benefits alongside standard regimens.
