Do not use fluorouracil topical if you are pregnant or planning a pregnancy. Discuss with your doctor appropriate forms of birth control before starting treatment with fluorouracil topical. Fluorouracil topical is available in a number of strengths and forms (creams and solutions).o not use other prescription or over-the-counter skin products without first talking to your doctor during treatment with fluorouracil topical. They may interfere with treatment or increase irritation to the skin. Drugs other than those listed here may also interact with fluorouracil topical.