Pros and Cons of Blue Light Therapy for Skin Cancer

Last updated: November 13, 2026

If your dermatologist recommends blue-light photodynamic therapy (PDT) for a rough, sun-damaged patch, they may be treating an actinic keratosis (AK). An AK is a precancerous lesion that can develop into squamous cell carcinoma. In the U.S., Levulan Kerastick plus BLU-U is approved for minimally to moderately thick AKs on the face, scalp or upper extremities. A separate red-light PDT regimen with Ameluz gained FDA approval for superficial basal cell carcinoma in adults in September 2026. (1, 2, 3, 4)

How blue-light PDT works and what it treats

Blue light PDT for skin cancer: a plain-language verdict

A healthcare professional applies a prescription solution containing aminolevulinic acid (ALA). Cells in the treated skin convert ALA into protoporphyrin IX. Blue light activates that compound, producing reactive forms of oxygen that damage cells in the treatment area. The BLU-U lamp peaks at about 417 nm. The treatment requires both the drug and the specified light source. (1, 5)

The American Academy of Dermatology (AAD) conditionally recommends ALA blue-light PDT for AKs. Consumer LED masks and panels are designed for other uses. If you've noticed a new growth, a changing mole or a sore that won't heal, have the spot examined before trying a device at home. (2, 1, 6)

Benefits of blue-light PDT

The clinical advantages that make blue light PDT worth considering

It can clear actinic keratoses

In the Levulan trials, all treated face or scalp AKs were clear at week 12 in 72% of patients (129 of 180) who received Levulan plus blue light and 11% (7 of 61) who received an inactive solution plus the same light. In a separate hand and forearm trial, the figures were 31% (42 of 135) and 13% (17 of 134). Both sets of trials allowed repeat treatment at week eight for lesions that remained. (1)

Several lesions can be treated at one visit

The Levulan label allows treatment of multiple individual AKs in one region during a session. If you have rough patches scattered across a larger area of sun damage, ask whether your dermatologist plans to treat individual spots or use a field-directed treatment that covers the surrounding skin as well. (1, 2)

Cosmetic results can compare favorably with freezing

A 2026 review of seven trials found that cosmetic ratings favored PDT over cryotherapy for AKs. The review combined several PDT regimens and also found more pain or burning with PDT. Either procedure can leave temporary skin changes. (7, 1)

Pain, recovery and recurrence

The real disadvantages: what the pro-PDT literature tends to understate

• Stinging or burning during illumination. In the Levulan trials on the face and scalp, at least half of patients reported severe stinging or burning at one or more treated spots. The upper-extremity trial reported severe stinging or burning in 9%. Ask the clinic how it handles discomfort during illumination. (1, 8)
• Sensitivity to bright light. The Levulan label instructs patients to protect the treated skin from sunlight and bright indoor light for at least 40 hours after the solution is applied. Use an opaque hat or clothing suited to the treatment site. The label calls for physical coverage because sunscreen alone provides insufficient protection during this window. (1)
• Visible skin reactions. Redness, swelling, peeling or crusting can last one to two weeks. In the Levulan face and scalp trials, redness and swelling had improved or returned to baseline by week four. Recovery can take longer at some sites. (8, 1)
• Lower response in thicker lesions. In the face and scalp trials, 88% of thin AKs and 78% of moderately thick AKs cleared by week eight. Those percentages count individual lesions. The pivotal trials excluded very thick AKs. (1)
• Recurrence after initial clearance. In a separate open-label study, 53% of the 72 patients whose face or scalp AKs had all cleared at month three had a recurrence by month 12. Counting individual lesions, 24% of the spots that had cleared at month three returned by month 12. (1)
• Time between drug application and light treatment. The labeled wait for Levulan is 14–18 hours for face or scalp lesions and three hours for upper-extremity lesions. Ask how the clinic schedules the two parts of treatment and what to bring to cover the area on the way home. (1)

How blue-light PDT compares with other treatments

In a 2019 trial involving multiple AKs on the head, an estimated 74.7% of patients receiving 5-FU remained free from treatment failure at 12 months, compared with 53.9% for imiquimod and 37.7% for methyl aminolevulinate PDT. The trial used a different PDT drug and measured how well the reduction in lesion count held up over a year. (11)

Where red-light PDT fits

Red light can reach deeper into the skin than blue light. European guidance describes red-light PDT as an option for selected low-risk basal cell carcinomas. The current U.S. Ameluz label includes adult superficial basal cell carcinoma when the gel is used with a specified RhodoLED red-light lamp that peaks at about 635 nm. In the pivotal trial, the main target lesion cleared on both clinical and microscopic examination in 66% of patients receiving Ameluz plus red light and 5% receiving an inactive gel plus the same light. That assessment took place 12 weeks after the start of the last treatment cycle. (13, 14, 3, 4)

Surgery remains the usual approach for high-risk basal cell carcinoma and invasive cutaneous squamous cell carcinoma. It is also the main treatment for localized melanoma. The dermatologist uses the diagnosis and tumor characteristics to plan treatment and follow-up. (10, 15, 16)

What to ask your dermatologist before booking

1. What is the diagnosis? If the diagnosis is uncertain or the lesion looks suspicious, ask whether it should be biopsied before treatment. (17, 6)
2. What does treatment need to cover? Ask whether the plan targets one or several AKs or treats a wider area of sun damage. Location and lesion thickness can change the options. (2, 1)
3. Which drug and lamp will the clinic use? Ask about the wait between application and illumination, the light protection you'll need and when the clinician will check for persistent or returning lesions. (1, 4)
4. Does anything in my medical history change the plan? Tell the clinician about porphyria, allergies to porphyrins or ingredients in the solution, and known skin sensitivity to blue light. Levulan lists those as contraindications. Bring your medication list too. Drugs such as tetracyclines can increase photosensitivity. (1)

Key Takeaways

Blue-light PDT with Levulan and BLU-U treats certain precancerous AKs and can address several spots in one visit. When weighing it against freezing or a prescription cream, ask about the chances of recurrence, pain during treatment and how long you'll need to shield the skin from bright light. (1, 2, 7)

FAQ

What are the downsides of blue-light PDT?

The main drawbacks are stinging or burning during illumination, temporary skin reactions and the need to shield the treated area from bright light. Some lesions need a second treatment, and cleared lesions can return. (1, 8)

Do dermatologists recommend blue-light PDT?

Yes, for selected actinic keratoses. The AAD's recommendation for ALA blue-light PDT is conditional. For a biopsy-confirmed skin cancer, treatment depends on the cancer type, the depth of the lesion and its risk of recurrence. (2, 10, 15, 16)

Can blue-light PDT damage the surrounding skin?

Skin exposed to the photosensitizing solution can react when the light is applied. Redness, swelling, crusting and temporary pigment changes can occur. The Levulan label also describes irritation when the solution reaches skin around the lesion. Follow the clinic's instructions for covering and caring for the treatment area. (1, 8)

How long does recovery take after blue-light treatment?

Redness, peeling or crusting can last one to two weeks, and some reactions take longer to settle. The light-protection window for Levulan starts when the medication is applied. Ask your clinic when it will assess healing and check that the lesions have cleared. (1, 8)

References

1. DailyMed. Levulan Kerastick prescribing information. See sections 1, 2, 4–7 and 14.
2. Eisen DB, Asgari MM, Bennett DD, et al. Guidelines of care for the management of actinic keratosis. Journal of the American Academy of Dermatology. 2021.
3. U.S. Food and Drug Administration. Ameluz supplemental approval for superficial basal cell carcinoma (NDA 208081/S-040). September 2026.
4. DailyMed. Ameluz prescribing information and RhodoLED lamp documentation. See sections 1 and 14.2 for the indication and trial results.
5. U.S. Food and Drug Administration. BLU-U summary of safety and effectiveness data (P990019). See the device description for the 417 nm peak.
6. Centers for Disease Control and Prevention. Symptoms of Skin Cancer.
7. Aldraibi S, Alharbi M, Alzubaidi K, et al. Comparative efficacy of photodynamic therapy versus cryotherapy for actinic keratosis. Journal of Cosmetic Dermatology. 2026.
8. Memorial Sloan Kettering Cancer Center. Photodynamic therapy: patient instructions and recovery.
9. National Cancer Institute. Skin Cancer Treatment (PDQ®), Patient Version.
10. American Academy of Dermatology. Basal cell carcinoma clinical guideline.
11. Jansen MHE, Kessels JPHM, Nelemans PJ, et al. Randomized Trial of Four Treatment Approaches for Actinic Keratosis. New England Journal of Medicine. 2019.
12. DailyMed. Imiquimod cream prescribing information.
13. British Association of Dermatologists and British Photodermatology Group. Guidelines for topical photodynamic therapy. British Journal of Dermatology. 2019.
14. Peris K, Fargnoli MC, Garbe C, et al. European consensus guideline for basal cell carcinoma, 2023 update. European Journal of Cancer. 2023.
15. Alam M, Armstrong A, Baum C, et al. Guidelines of care for the management of cutaneous squamous cell carcinoma. Journal of the American Academy of Dermatology. 2018.
16. National Cancer Institute. Melanoma Treatment (PDQ®), Patient Version.
17. Kandolf L, Peris K, Malvehy J, et al. European consensus guideline for actinic keratoses and field cancerization. Journal of the European Academy of Dermatology and Venereology. 2024.