Photodynamic Therapy (PDT): Uses, Procedure, Recovery and Risks
Updated: 3 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: November 2026 · How we review
Quick Answer: What is photodynamic therapy?
Photodynamic therapy (PDT) is a treatment that combines a light-sensitive drug with a special light to destroy abnormal cells, such as precancerous skin patches and some early cancers. The light triggers a reaction that kills the targeted cells while sparing most healthy tissue. A session lasts 15 to 90 minutes, and treated skin heals in two to six weeks.
What the research says
PDT clears actinic keratoses about as well as freezing, with better cosmetic results. In a meta-analysis of 7 randomized trials with 1,233 patients, lesion clearance was similar for PDT and cryotherapy, while good cosmetic outcomes were reported in 74.6% of PDT patients versus 49.1% after cryotherapy. PDT caused more burning and pain, and cryotherapy caused more blisters. (Aldraibi et al., Journal of Cosmetic Dermatology, 2026) [2]
Daylight-style PDT hurts less but clears slightly fewer lesions. Across 4 studies with 171 participants, indoor or simulated daylight PDT cut pain during light exposure by about 4.4 points and was preferred by patients, but complete clearance at 3 months was somewhat lower than with conventional lamp-based PDT. (Al-Otaibi et al., Photodiagnosis and Photodynamic Therapy, 2026) [3]
Key takeaways
PDT uses a light-sensitive drug (a photosensitizer) plus light to destroy abnormal cells while limiting damage to healthy tissue. [1]
Its most common uses are skin cancers, actinic keratosis and Bowen disease, but it is also used for Barrett's esophagus and some internal cancers. [1]
A session takes 15 to 90 minutes, and most people go home the same day. [1]
Treated areas stay sensitive to light for a while, so you need to stay indoors, especially for the first 48 hours. [1]
Full healing usually takes two to six weeks. [1]
What is photodynamic therapy?
Photodynamic therapy, often shortened to PDT, destroys harmful cells, including some cancer cells, with a combination of light and a drug called a photosensitizer. On its own the drug does nothing. When light reaches it, the drug triggers a chemical reaction that kills the cells holding it. [1]
Because the light has to reach the abnormal cells, PDT works best on the skin and on the lining of organs that a light source can reach. [1]
PDT works in four steps, from giving the light-sensitive drug to destroying abnormal cells.
Conditions treated with photodynamic therapy
Type of condition | Examples |
Skin precancers and cancers (most common use) | Actinic keratosis, Bowen disease and some skin cancers |
Precancer of the esophagus | Barrett's esophagus |
Internal cancers | Bile duct, bladder, esophageal, head and neck, lung and pancreatic cancers |
Noncancer skin conditions | Severe acne and sun-damaged skin (photoaging) |
Sources: [1]
The most common target of PDT is explained in our guide to actinic keratosis. You can also read about related skin cancers such as basal cell carcinoma and squamous cell carcinoma of the skin.
How do you prepare for photodynamic therapy?
Before treatment, your provider reviews your medical history and checks whether you are sensitive to light. [1]
Tell your provider if you get cold sores. PDT can trigger a flare-up, and medicine taken beforehand can help prevent it. [1]
Plan to stay indoors after treatment, because the treated area will be sensitive to light. [1]
Bring sun-protective clothing and a hat for the trip home. [1]
What happens during photodynamic therapy?
PDT is done in steps. How long each step takes depends on the drug and on the size of the area being treated. [1]
Key numbers to know before a PDT session.
You receive the photosensitizer as a solution on the skin, through a vein (IV) or as a pill. [1]
The drug is absorbed. All cells take it up, but abnormal cells hold on to it longer. This waiting period lasts from minutes to a few days. [1]
The treatment area is exposed to light from a laser, an LED lamp or natural daylight. For areas inside the body, a thin, flexible tube carries the light. [1]
The light activates the drug, which reacts with oxygen in the cells and destroys the unhealthy ones. [1]
Photodynamic therapy at a glance
Item | Typical detail |
Session length | 15 to 90 minutes, depending on the size of the area |
Light sources | Laser, LED lamp or daylight; a thin tube for internal areas |
Setting | Outpatient, usually home the same day |
Repeat sessions | Sometimes needed; your provider decides |
Full healing | About two to six weeks |
Sources: [1]
Does photodynamic therapy hurt?
The light part of PDT can be uncomfortable. People describe anything from warmth to burning or stinging, depending on the drug and light source. Cooling fans, ice packs and medicines can help, so tell your provider if it hurts. [1] Studies also show that daylight-style PDT is less painful than conventional lamp-based treatment. [3]
What happens after photodynamic therapy?
Most people go home the same day. The main task afterward is protecting the treated area from light, because the drug takes time to leave your body and keeps your skin sensitive. [1]
Stay indoors as much as you can, especially for the first 48 hours. [1]
Avoid bright indoor lights and strong reading or examination lamps. [1]
Wear sun-protective clothing and a hat if you have to go outside. [1]
Avoid reflective places such as beaches. [1]
Do not use helmet-style hair dryers. [1]
How long is recovery from photodynamic therapy?
Full healing usually takes about two to six weeks, depending on the area treated, although side effects often start to ease sooner. [1]
What treated skin usually looks like day by day after PDT.
Time after treatment | What to expect |
Day 1 | Redness on lighter skin, or darker discoloration on darker skin |
Day 2 | Redness or discoloration may get stronger |
Days 3 to 7 | Itching or peeling; blisters are rare |
1 to 2 weeks | Skin begins returning to normal |
2 to 6 weeks | Treated area fully healed |
Sources: [1]
For skin conditions, results are usually semi-permanent and last several months. Your provider will tell you whether more sessions are needed. [1]
What are the benefits and risks of photodynamic therapy?
PDT may cure some precancers and early cancers, and in other cases it can extend life or relieve symptoms. It causes very little scarring and, when given correctly, has no long-term side effects. [1] In trials for actinic keratosis, it also gave better cosmetic results than freezing (cryotherapy). [2]
Risk or side effect | What it means |
Light sensitivity | Skin stays sensitive to light until the drug leaves your body |
Skin reactions | Itching, stinging, burning, swelling, discoloration, scales, crusts or blisters |
Trouble swallowing | Temporary, after PDT of the esophagus |
Shortness of breath | Possible after PDT of the lungs |
Skin infection | Very rare |
Sources: [1]
When should you call a doctor after photodynamic therapy?
Contact your healthcare provider if you have severe discomfort while you recover. They may suggest home care, over-the-counter products or a prescription treatment. [1]
Conclusion
Photodynamic therapy uses a light-activated drug to destroy precancer and some cancer cells while sparing most healthy tissue. It is most often used for skin conditions such as actinic keratosis, takes 15 to 90 minutes and usually lets you go home the same day. [1]
The key to a smooth recovery is protecting the treated area from light, especially in the first two days. Ask your provider how PDT compares with other options for your condition, and make sure you know how to protect your skin while it heals. [1]
Keep learning: Read our actinic keratosis guide to understand the sun-damaged patches that PDT treats most often.
Frequently asked questions
What is photodynamic therapy used for?
PDT is mainly used for skin cancers, actinic keratosis and Bowen disease. It is also used for Barrett's esophagus, some internal cancers, severe acne and sun-damaged skin.
How does photodynamic therapy work?
A light-sensitive drug builds up in abnormal cells. When light reaches it, the drug reacts with oxygen and kills those cells.
How long does a PDT session take?
A session usually lasts 15 to 90 minutes, depending on the size of the treated area.
Does photodynamic therapy hurt?
The light can feel warm, stinging or burning. Fans, ice packs and medicines help ease the discomfort.
Can I go home after photodynamic therapy?
Yes. Most people go home the same day but must protect the treated area from light.
How long should I avoid light after PDT?
Stay indoors as much as possible, especially for the first 48 hours, and avoid bright lamps and direct sun.
What does skin look like after photodynamic therapy?
Expect redness or discoloration in the first days, then itching or peeling for up to a week.
How long does it take to heal after PDT?
Full healing usually takes about two to six weeks, depending on the area treated.
Will I need more than one PDT session?
Sometimes. Your provider decides, and results for skin conditions usually last several months.
What are the risks of photodynamic therapy?
Risks include light sensitivity, skin irritation and blistering, and rarely skin infection. PDT inside the body can cause temporary swallowing or breathing problems.
How do I prepare for photodynamic therapy?
Your provider reviews your medical history and checks whether you're sensitive to light [1]. Tell them if you get cold sores, because PDT can trigger a flare-up, plan to stay indoors afterward, and bring sun-protective clothing and a hat for the trip home [1].
When should I call my doctor after photodynamic therapy?
Contact your provider if you have severe discomfort while you recover; they may suggest home care, over-the-counter products or a prescription treatment [1].
Related Reading
LED Light Therapy: Colors, Benefits and Risks explains LED light therapy for skin.
Actinic Keratosis: Symptoms, Causes, Diagnosis, and Treatment Options explains the rough, sun-damaged patches that PDT treats most often.
What Is Basal Cell Carcinoma? Symptoms, Causes, and Treatment covers the most common type of skin cancer and how it is treated.
Squamous Cell Carcinoma of the Skin: Symptoms, Causes, and Treatment Explained describes a skin cancer that can develop from untreated actinic keratosis.
Acne: Complete Guide to Symptoms, Causes, Diagnosis, and Treatment reviews acne treatments, including options for severe cases.
References
Cleveland Clinic. Photodynamic Therapy: What It Is, Procedure & Recovery. Cleveland Clinic. Last updated February 13, 2025. https://my.clevelandclinic.org/health/procedures/photodynamic-therapy-pdt
Aldraibi S, Alharbi M, Alzubaidi K, et al. Comparative Efficacy of Photodynamic Therapy Versus Cryotherapy for Actinic Keratosis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Cosmet Dermatol. 2026;25(4):e70749. PMID 41964358. https://doi.org/10.1111/jocd.70749
Al-Otaibi NM, Alhadeyah MS, Al-Rashid AH, et al. Efficacy, tolerability, and patient preference of indoor, simulated, or artificial daylight photodynamic therapy versus conventional lamp-based photodynamic therapy for actinic keratosis: A systematic review and meta-analysis. Photodiagnosis Photodyn Ther. 2026;61:105643. PMID 42685922. https://doi.org/10.1016/j.pdpdt.2026.105643
Medical disclaimer
This article is for general education only and does not replace advice from a qualified healthcare professional. Talk to your doctor about your own diagnosis and treatment, and seek emergency care right away for severe or sudden symptoms.
Comments