When is topical 5-fluorouracil recommended for actinic keratosis?

Actinic keratosis is a rough, scaly area caused by long-term sun damage. Several spots may be present, including areas that are easier to feel than see. Topical 5-fluorouracil treats a defined surface rather than removing one isolated spot immediately, so a dermatologist may consider it when the affected field contains visible or early changes.

The treated skin commonly becomes red, irritated, tender, or crusted as the medicine acts on abnormal cells. The appearance can vary across the treatment area. Your clinician will explain the expected reaction and decide whether the diagnosis needs confirmation before treatment.

Apply the prescribed amount to the exact area and follow the schedule given. Wash your hands after use, avoid the eyes and mucous membranes, and do not add other irritating products unless your clinician approves them. Protect the area from sunlight with clothing and sunscreen suitable for the site. Keep the review appointment even if the surface looks clearer.

A dermatologist may discuss alternatives, including freezing, scraping, or another field treatment, depending on the number, thickness, and location of the lesions. Read more about [Topical 5-Fluorouracil](/treatments/medical-dermatology/topical-5-fluorouracil/).

Seek advice if swelling, pain, blistering, or open sores interfere with normal activities, or if you are unsure whether the reaction is within the expected range. Arrange a prompt skin review for a rapidly thickening patch, persistent tenderness, bleeding, or a sore that does not heal. A lesion that changes despite treatment may need a closer examination or biopsy.

Ask which lesions or skin field should be treated, what reaction to expect, how to care for crusting, and when the result will be assessed. Ask whether a biopsy or another treatment is more appropriate for a thick, tender, or isolated lesion.