How to know when to stop applying Fluorouracil Cream USP 5%?

How long you use fluorouracil cream for depends on what you are treating. The dosing information is given below but I would suggest that you confirm it with your dermatologist/doctor.

Fluorouracil topical Dosing Information

Usual Adult Dose for Skin Cancer:

Superficial basal cell carcinoma:

Apply 5% cream or solution to lesions twice daily with gloves or nonmetal applicators.

Treatment should continue for at least 3 to 6 weeks, and may be required for as long as 10 to 12 weeks to resolve the lesions.

Usual Adult Dose for Keratosis:

Actinic or solar keratosis:
0.5% cream (microsphere formulation): Apply to the affected area once a day. May be applied with the fingers and hands should be washed immediately afterward.

1%, 2%, 5% cream or 2%, 5% solution: Apply to the affected area twice daily with gloves or nonmetallic applicator, using sufficient amount to cover the lesions.

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The usual duration of therapy is 2 to 4 weeks, until the inflammatory response reaches the erosion state, at which time treatment is discontinued. Lesions may not heal completely for 1 to 2 months after fluorouracil therapy has been discontinued.

Solar keratoses which do not respond to treatment should be biopsied to confirm the diagnosis.

http://www.drugs.com/mtm/fluorouracil-topical.html