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Phototherapy for psoriasis (especially narrowband UVB, NB-UVB) is a widely used, safe, and effective physical treatment in clinical practice, suitable for moderate to severe plaque psoriasis, guttate psoriasis, and other forms. However, phototherapy is not as simple as "sunbathing"; improper operation may cause sunburn, hyperpigmentation, and even long-term skin cancer risk. The following are key phototherapy precautions for psoriasis summarized by dermatologists:

1. Must be performed in a professional medical institution

Phototherapy should be initiated only after a dermatologist evaluates indications and contraindications; do not use ultraviolet lamps at home on your own.

Treatment doses should be individualized based on skin phototype (Fitzpatrick classification), prior history of sunburns, and current lesion status, and should be increased gradually.

Although home phototherapy devices are available on the market, they should also be used under physician guidance, with regular follow-up visits to adjust the regimen.

2. Preparations before treatment

Clean the skin: Bathe or cleanse lesions before treatment to remove thick scales (which can enhance light penetration), but avoid using skincare products that contain photosensitizing ingredients (such as certain essential oils or retinoids).

Cover normal skin: Non-lesional areas such as the face and genitalia should be covered; male patients need special protection for the genitals (e.g., dark underwear or a dedicated protective shield).

Wear protective goggles: Specialized UV-protective goggles must be worn during each treatment to prevent lens and retinal damage.

Report medication history: Inform the physician in advance if you are taking photosensitizing drugs such as tetracycline antibiotics, quinolones, thiazide diuretics, psoralens, or retinoids.

3. Care during and after treatment

Maintain stable positioning: ensure lesions are fully exposed to the light source and avoid shielding.

Document reactions: if notable erythema, burning pain, or blisters occur, inform the physician immediately; therapy may need to be paused or the dose reduced.

Post-treatment moisturization: skin is prone to dryness after phototherapy; recommend applying a non‑irritating moisturizer within 2 hours.

Strict sun protection: on the day of treatment and the following day, take enhanced sun-protection measures when outdoors (hat, long sleeves, SPF30+ broad‑spectrum sunscreen), and avoid additional natural sunlight exposure that could cause sunburn.

4. Populations for Whom Treatment Is Contraindicated and Should Be Approached with Caution

The following conditions are contraindications for phototherapy:

Patients with photosensitive disorders (such as lupus erythematosus, polymorphic light eruption);

A history of skin cancer or hereditary cancer syndromes (such as xeroderma pigmentosum);

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Unprotected cataract;

Pregnancy (PUVA therapy is especially contraindicated);

Patients with abnormal liver function (PUVA requires oral psoralen, which is hepatotoxic).

Note: NB-UVB is relatively safe; PUVA (photochemotherapy) requires medication plus UVA exposure and has more side effects, so it is now less often used as a first-line option.

5. Key Points for Long-term Management

The treatment course is usually 2–3 months, 2–3 times per week; most patients respond after 10–20 sessions.

Do not over-pursue "darkening": skin darkening is a defensive response and does not indicate better efficacy.

Regular follow-up: long-term phototherapy patients should have their skin photoaging and cancer risk evaluated by a physician every 6–12 months.

Combination therapy is better: phototherapy is often used with topical agents (such as calcipotriol), emollients, or systemic drugs to improve efficacy and reduce total irradiation dose.

✅ Physician’s Reminder:

Phototherapy is a "powerful tool" for psoriasis treatment but must be used scientifically,规范、and individualized. Do not increase frequency or dose on your own in pursuit of rapid effect, and do not believe the misconception of "using home lamps casually." Under professional guidance and with adherence to treatment, most patients can achieve significant and lasting remission.