Knowledge of Phototherapy 3
25. Can Lactating Women Receive UV Phototherapy?
Answer: Lactation is not a contraindication for phototherapy. NB-UVB and BB-UVB phototherapy can be used during lactation, which is safe and effective. Systemic PUVA treatment is not recommended for lactating patients because after treatment, photosensitizers may still remain in the body for 24 hours or even longer [13]. In comparison, red light therapy for face is often chosen for its gentle approach during sensitive periods.
26. What Are the Most Common Short-Term Adverse Reactions of UV Phototherapy?
Answer: The common short-term adverse reactions of UV phototherapy include dry skin, itching, pain, erythema, blisters, enhanced photosensitivity reactions of photosensitive drugs and foods, and exacerbation of photosensitive diseases [14]. In contrast, LED face light therapy typically has fewer short-term side effects, with mild warmth or temporary redness being rare.
27. Why Does the Skin Turn Red or Black After UV Phototherapy?
Answer: The redness of the skin after UV phototherapy, namely UV erythema, is a relatively mild phototoxic reaction caused by UV irradiation, also known as sunburn. Its mechanism is that UV irradiation damages the lysosomes of vascular endothelium, leading to dermal inflammatory reactions, followed by vasodilation, increased blood flow, and increased vascular permeability, making the skin look red. UV erythema can be divided into immediate erythema and delayed erythema. Immediate erythema usually occurs during or within a few minutes of UV irradiation, while delayed erythema generally appears after 2-10 hours. Observing the erythema after phototherapy can determine the dose of subsequent phototherapy. The darkening of the skin after UV phototherapy is sun tanning, also known as sun darkening, which is manifested as skin darkening due to a series of reactions such as melanin oxidation and redistribution, melanocyte proliferation, and increased melanin caused by UV irradiation. Pigmentation includes two stages: immediate pigmentation and delayed pigmentation. The ability of skin darkening is related to the ability of melanocytes to produce melanin, the amount of melanin in each melanosome, and the distribution of melanosomes. This differs from red light therapy for eczema, which primarily stimulates collagen production without triggering melanin changes.
28. Does UV Phototherapy Damage the Eyes?
Answer: UV rays damage the eyes. Excessive UV rays can cause acute corneal reactions, manifested as eye pain, photophobia, tearing, blurred vision, etc. UV rays can also cause lens damage, which is a long-term and chronic accumulation process. As the amount of UV radiation increases, the incidence of cataracts also increases significantly [1]. Similarly, UV rays can also damage the retina [15]. Therefore, it is necessary to protect the eyes during UV phototherapy. A good pair of goggles can play a very good protective role. During UV phototherapy, you should wear special UV protective glasses or eye masks. As long as the eyes are well protected, there will be no eye damage. LED face light therapy, on the other hand, uses lower-intensity light and typically requires less stringent eye protection, though caution is still advised.
29. How to Protect Periocular Skin Lesions During Phototherapy?
Answer: When treating periocular skin lesions with phototherapy, sufficient light shielding protection for the eyes must be done, such as wearing phototherapy goggles (Figure 1-11), sticking tape on the eye slits, etc., before irradiation. For patients with incomplete eyelid closure, contact lenses that can block UV rays can be selected [15]. During irradiation, phototherapy devices with a relatively small irradiation area, such as targeted phototherapy, or phototherapy devices that can be closely attached to the skin for treatment can be selected to reduce light leakage. If home phototherapy is performed, it needs to be operated by another person, and the operator should also fully protect the eyes. This level of caution is less critical for red light therapy for face, but precise targeting remains important to avoid unnecessary exposure.
30. What Are the Most Common Long-Term Adverse Reactions of UV Phototherapy?
Answer: The most common long-term adverse reactions of UV phototherapy are mainly pigmentation, photoaging, and induction of skin tumors. Currently, there is no clinical evidence that NB-UVB is related to human skin tumors, but high cumulative dose PUVA treatment may be related to non-melanoma skin tumors [16]. Long-term use of UV phototherapy also contrasts with red light therapy for eczema, which has shown no significant long-term risks in clinical observations.
31. Does UV Phototherapy Cause Cancer?
Answer: Carcinogenesis is a potential adverse reaction of UV phototherapy. High cumulative dose PUVA treatment may induce the occurrence of skin tumors [17]. A study found that 14 male psoriasis patients developed malignant tumors in the genital area after PUVA treatment [18]. NB-UVB does not require the use of psoralen and is safer than PUVA. Currently, there is no study showing that NB-UVB increases the risk of skin cancer. A follow-up study of more than 5 years on 3867 phototherapy patients (97% with Fitzpatrick type Ⅰ～Ⅲ skin) showed that NB-UVB treatment was not significantly associated with the occurrence of melanoma or non-melanoma skin cancer. Unlike UV phototherapy, red light therapy for face has no known links to cancer risk, as it operates at different wavelengths and intensities.
32. Does UV Phototherapy Accelerate Skin Aging?
Answer: A long-term adverse reaction of UV phototherapy is photoaging, that is, UV irradiation leads to skin aging. Ultraviolet (UV) irradiation can accelerate the degradation of skin collagen, reducing skin elasticity and strength; it also accelerates the aging of fibroblasts, and the accumulation of dysfunctional fibroblasts in the skin leads to skin photoaging. Its characteristics include the formation of fine and coarse wrinkles, rough and thickened skin, laxity, deepened skin furrows, and a leathery appearance. This is in contrast to red light therapy for eczema, which is often used to combat signs of aging by boosting collagen and elastin production.
33. How to Protect Normal Skin and Reduce Photoaging?
Answer: To reduce photoaging of normal skin, we can start from three aspects: (1) Maintain a healthy lifestyle, such as regular work and rest, and less staying up late; (2) Strengthen physical photoprotection, such as the use of sun umbrellas, sun hats, and sunscreens; (3) Appropriately use drug intervention, such as antioxidant drugs and anti-inflammatory drugs. If you are a phototherapy patient, you should also protect your normal skin during phototherapy. Alternatives like red light therapy for face can support skin health without accelerating aging.
34. Will UV Phototherapy Reduce Immunity?
Answer: UV phototherapy can regulate immunity, and it cannot be simply understood as inhibiting or reducing immunity. Low-dose UV irradiation has a certain promoting effect on immune function, and as the dose increases, the body's immune function will increase accordingly. However, if the dose is too large and the irradiation frequency is too frequent, immune suppression will occur. Therefore, patients with tuberculosis and other diseases are prohibited from whole-cabin phototherapy. In short, UV phototherapy should follow certain dose adjustment principles, and the treatment plans vary greatly for different diseases, so it needs to be carried out according to the treatment plan formulated by the doctor.
35. What Measures Can Reduce the Adverse Reactions of UV Phototherapy?
Answer: Sufficient protection can reduce the adverse reactions of UV phototherapy. Pay attention to the protection of normal skin around the skin lesions, avoid excessive sun exposure after phototherapy, and strengthen the moisturizing care of the irradiated skin. If you need to go out during treatment, you should try to avoid light and take sun protection measures, such as wearing a sun hat, sun-protective clothing, and applying sunscreen. At the same time, pay attention to avoiding the intake of photosensitive drugs and foods. Apply skin moisturizer at least twice a day during phototherapy. For milder options, red light therapy for face may help maintain skin hydration with fewer precautions.
