UVB Phototherapy

What is UVB Phototherapy?

UVB phototherapy uses shortwave ultraviolet radiation to treat various skin conditions, including psoriasis. This treatment works by suppressing DNA synthesis, thereby reducing inflammation.

Sunlight naturally produces three types of ultraviolet radiation: UVA, UVB, and UVC. As sunlight passes through the ozone layer, all UVC and most UVB radiation are absorbed, leaving approximately 95% UVA and 5% UVB to reach Earth. While UV radiation can provide relief for some psoriasis patients, uncontrolled exposure to sunlight may lead to skin cancer and premature aging.

Types of UVB Phototherapy

1. Narrowband UVB (nbUVB):

  • Emits a specific wavelength of 311–312 nm.
  • Offers shorter treatment times, better results, and longer remission periods compared to broadband UVB.
  • Preferred for its safety and effectiveness.

2. Broadband UVB (bbUVB):

  • An older technology with a broader wavelength range (290–320 nm).
  • Requires longer exposure times and is less effective than nbUVB.

Key Benefits of Narrowband UVB

  • Effective Treatment: Provides relief for conditions like psoriasiseczema, and vitiligo.
  • No Photo sensitising Drugs: Unlike UVA treatments, nbUVB does not require additional medications.
  • Convenience: Requires fewer and shorter treatment sessions compared to broadband UVB.

How UVB Phototherapy Works

  • UVB phototherapy is delivered using specialised cabinets equipped with fluorescent light tubes that target the affected areas.
  • Initial sessions involve very short exposure times (a few seconds) to assess skin tolerance. Treatment duration gradually increases to 10–15 minutes per session.
  • Phototesting is often performed to determine the minimum dose that produces skin redness (MED testing). The starting dose is typically 70% of the MED, escalating by 20% per session, provided there are no side effects.
  • For full-body treatments, patients are undressed, with genitalia covered and eyes protected using goggles or a face mask.

Uses of UVB Phototherapy

Primary Conditions Treated:

  • Psoriasis: Reduces inflammation and often leads to remission for several months.
  • Dermatitis (Eczema): Effective for managing severe cases over prolonged treatment durations.
  • Vitiligo: Stimulates repigmentation through immune modulation.

Additional Conditions Treated:

  • Cutaneous T-cell lymphoma
  • Lichen planus
  • Polymorphic light eruption
  • Pruritus

Contraindications to UVB Phototherapy

Absolute Contraindications:

  • History of melanoma or skin cancer.
  • Familial Atypical Multiple Mole and Melanoma (FAMMM) syndrome, also known as dysplastic naevus syndrome.
  • Systemic lupus erythematosus.
  • Dermatomyositis (juvenile or adult-onset).
  • Genetic conditions increasing cancer risk, such as xeroderma pigmentosumGorlin syndromeBloom syndrome, or Cockayne syndrome.
  • Patients unable to comply with safety measures or medically unfit to stand during treatment (e.g., severe cardiovascular or respiratory disease).

Relative Contraindications:

  • Previous exposure to arsenic or ionising radiation.
  • Pregnancy (requires folic acid supplementation and monitoring).
  • Current premalignant skin conditions.
  • Concomitant use of immunosuppressive therapies (e.g., cyclosporine, azathioprine, mycophenolate).
  • Photo-induced epilepsy.
  • Cataracts.
  • Bullous pemphigoid or pemphigus.
  • Significant liver dysfunction.
  • Age under 16 years.

Benefits of UVB Phototherapy

  • Effective for both localised and full-body treatment.
  • Lower cancer risk than PUVA due to reduced UV exposure and narrower wavelengths.
  • Home phototherapy may be an option in some cases.
  • A safer and often more affordable alternative to systemic therapies.

Disadvantages of UVB Phototherapy

  • Requires frequent visits to the clinic, typically three times a week

Side Effects and Risks of UVB Phototherapy

Short-Term Side Effects:

  • Dry skin.
  • Itchy, red rash within 6–24 hours post-treatment.
  • Occasional sunburn.
  • Reactivation of herpes simplex virus (cold sores), preventable with protective lip balm.
  • Worsening of pre-existing skin conditions.
  • Provocation of photodermatoses.
  • Increased pigmentation in treated areas.

Long-Term Side Effects:

  • Skin aging.
  • Increased risk of skin cancer, particularly after more than 500 treatments, warranting regular cancer surveillance.

Instructions for Patients Receiving UVB Phototherapy

  1. Attend Scheduled Appointments: Ensure punctuality and allocate time for preparation.
  2. Inform the Clinic: Report any medical conditions (e.g., eye diseases) and medications that may heighten UVB sensitivity.
  3. Avoid Unapproved Products: Do not use ointments, cosmetics (perfumes, coal tar), or any other products unless advised by your doctor.
  4. Moisturisers and Sunscreens: Avoid applying these within two hours before treatment, as they can interfere with UVB absorption. Apply them as directed after treatment.
  5. Limit UV Exposure: Avoid additional ultraviolet exposure, including sunlight and tanning beds.
  6. Use Protective Gear: During treatment, wear goggles or a face mask to protect the eyes, and ensure sensitive areas are covered.
  7. Report Side Effects: Notify the photo therapy team of any adverse effects.
  8. Follow Up Regularly: Maintain consistent follow-ups with your dermatologist to monitor progress and adjust treatment as needed.

This structured and monitored approach ensures UVB photo therapy remains a safe, effective, and controlled treatment for a variety of skin conditions.

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