Résumé
Topical 5-FU has been used for many years in the treatment of skin diseases such as Actinic Keratosis (AK), and its safety profile is considered to be well characterised. While studies have demonstrated that 5-FU is effective on AK lesions, cutaneous toxicity leading to skin reactions appears to occur very commonly in treated patients. Indeed, after topical administration of 5-FU, these local inflammatory episodes are expected to occur, in line with 5-FU's cytotoxic mechanism of action. These reactions have an impact on the patient's life and can manifest as discomfort and significant effects on the skin, especially as AK are most often located on the face. Depending on the patient's tolerance to the treatment, this may result in premature discontinuation of treatment. Some AK lesions can develop into skin cancer, which has a significant impact on the patient's general health.Systemic side effects occur in isolation. The probability of percutaneous absorption of 5-FU causing these effects is low. However, exposure may increase in certain cases when the product is applied to areas where the barrier function is impaired, in cases of DPD deficiency or when the treatment is misused. Improving the prevention, diagnosis and management of AE could help reduce the toxicity of topical 5-FU and its clinical effects.