NB-UVB side effects: what to know

The treated skin may look pink or feel warm after exposure. Dryness or temporary itch can occur as the skin responds. A dose that is too strong for your skin can produce marked redness, tenderness, swelling, or blisters. Longer-term changes such as uneven darkening or lightening may also be discussed during follow-up. The reaction is interpreted alongside your skin type, medicines, and the condition being treated.

Use the moisturiser recommended by your clinic and avoid fragranced products on recently treated skin. Do not increase the dose, add sun exposure, or use a tanning bed between appointments. Tell the phototherapy team about every new medicine and any reaction before the next session; they may delay treatment or alter the dose. Protect the eyes exactly as instructed and avoid scratching irritated skin.

Contact the clinic promptly for intense or persistent redness, swelling, painful burning, crusting, or blisters. Report eye pain, marked light sensitivity, or visual changes without delay. Seek urgent care for facial swelling, breathing difficulty, faintness, or a widespread blistering rash. New or worsening itchy skin and scaling can also signal that your treatment plan needs review.

Ask which reactions are expected for your dose, when to moisturise, whether a medicine increases light sensitivity, and what symptoms mean your next session should be postponed.