How long does narrowband UVB phototherapy take to work for prurigo nodularis?

Prurigo nodularis can involve a persistent itch–scratch cycle, so the first useful sign may be less urge to scratch rather than an immediate flattening of every nodule. Skin texture and dark or light marks can take longer to settle after active inflammation calms. Response is influenced by the number and location of nodules, skin sensitivity, and whether other treatments are used alongside phototherapy.

Keep appointments as directed and avoid doubling up after a missed session unless the clinic advises it. Protect treated skin from unplanned UV exposure, use prescribed creams as instructed, and keep nails short to reduce injury from scratching. Report excessive redness, soreness, or a change in itch promptly so the dose and wider treatment plan can be adjusted.

Seek prompt advice for blistering, severe burning, open sores, pus, or rapidly worsening pain around a nodule. Urgent care is needed for facial swelling or breathing difficulty. Book a reassessment when the course is complete, or sooner if nodules continue appearing, sleep is being disrupted, or the diagnosis seems uncertain.

Ask what improvement will be measured first, how itch will be tracked, how missed sessions should be handled, and when another treatment should be considered if nodules remain active.