Photodynamic therapy (PDT) is a targeted medical treatment that utilizes light and a specialized medication called a photosensitizer to eliminate cancerous, precancerous, and certain other problematic cells. When activated by light, the photosensitizer triggers a chemical reaction that selectively destroys abnormal cells while minimizing damage to healthy tissue. This approach makes PDT a versatile option for a growing number of conditions, from skin cancer to macular degeneration.
How Photodynamic Therapy Works
The process involves two key steps. First, a photosensitizer is administered, either topically, orally, or intravenously, depending on the target area. This medication accumulates in abnormal cells, making them light-sensitive. After a waiting period (hours to days), the area is exposed to a specific wavelength of light (blue or red), activating the photosensitizer. This activation generates a form of oxygen that selectively kills the targeted cells.
There are two primary types of PDT: conventional (clinic-based), using laser or LED lights, and daylight PDT (dPDT), which utilizes natural sunlight. dPDT often involves the application of sunscreen to protect surrounding skin from damage. While potentially less painful, dPDT is less extensively researched than its conventional counterpart.
FDA-Approved and Emerging Uses
Initially developed for skin cancer treatment, PDT has expanded its applications. The FDA has approved PDT for:
- Actinic Keratoses: Precancerous skin lesions, particularly on the face, scalp, and arms.
- Superficial Basal Cell Carcinoma: A type of skin cancer.
- Bowen’s Disease: Squamous cell carcinoma in situ.
- Age-Related Macular Degeneration (AMD): PDT, often combined with anti-VEGF injections, can slow the progression of wet AMD and improve vision in some cases.
Beyond these approved uses, research suggests potential benefits for:
- Acne Vulgaris: Emerging evidence supports PDT as an effective treatment for moderate to severe acne.
- Psoriasis: Some studies suggest PDT as a promising, underutilized treatment option.
- Rosacea and Photoaging: Off-label applications are being explored for these skin conditions.
- Wound Healing and Antimicrobial Uses: PDT shows promise in stimulating the body’s immune response and fighting infections.
Preparing for and Undergoing PDT
Before treatment, inform your doctor about all medications and supplements you take. Individuals with a history of cold sores may need antiviral medication beforehand. If using retinoids, discontinue them for a week prior.
During the procedure, most sessions last 15–90 minutes. Patients may experience tingling or burning sensations, which can be managed with fans, ice packs, or brief pauses. Multiple sessions may be required.
Recovery and Potential Side Effects
Recovery typically takes 2–6 weeks, depending on the treated area. Common side effects include redness, peeling, crusting, and swelling, which usually resolve within days to weeks. Hyperpigmentation (darkening of the skin) is possible, especially in individuals with darker skin tones. Sun protection is crucial during recovery.
Rare but possible complications include cough, difficulty swallowing, stomach pain, or shortness of breath, which should be reported to your doctor immediately.
Long-Term Follow-Up
For skin cancers and actinic keratoses, follow-up appointments are scheduled about four weeks post-treatment to assess efficacy. Additional treatments may be necessary for optimal results.
The Takeaway: Photodynamic therapy is a versatile, targeted treatment with expanding applications. While generally safe and effective, understanding the procedure, potential side effects, and long-term follow-up is crucial for successful outcomes.
Editorial Sources: Every health-related claim in this article is backed by peer-reviewed studies, board-certified medical experts, and top institutions. The full list of sources is available at the end of the article
