Fluorouracil is an antimetabolite that works by interfering with the growth of abnormal cells in the body.
Fluorouracil belongs to the family of antimetabolite chemotherapy agents. It works by interfering with the growth of abnormal cells, especially those found in the skin and certain cancers. In Hong Kong, fluorouracil is the active ingredient in products such as Efudex and the generic preparation labelled simply Fluorouracil.
A handful of topical medicines available on the Hong Kong market use fluorouracil as the key component. The most widely recognised brand is Efudex, which comes as a cream or gel for external use. The same ingredient is also sold under the generic name Fluorouracil, typically in similar cream or ointment forms. Both products are supplied in a range of strengths (for example, 0.5 % or 5 % w/w) and may be combined with other agents for specific clinical needs. They are prescription-only medicines regulated by the Hong Kong Department of Health.
Fluorouracil-containing creams are commonly prescribed for:
These conditions involve abnormal cells that proliferate rapidly. By disrupting DNA synthesis, fluorouracil helps the body shed the affected tissue, allowing healthier skin to grow in its place. The medication is used by adults and older teenagers, but the exact suitability is decided by a qualified health professional.
Fluorouracil mimics a normal building block of DNA called uracil. When cells try to use it, the drug blocks the production of new DNA, which stops rapidly dividing cells from multiplying. Because cancerous or pre-cancerous skin cells divide faster than normal cells, they are more vulnerable to this effect. The result is a gradual clearing of the abnormal tissue over days to weeks after treatment begins.
Most people who use fluorouracil creams notice mild, local reactions such as:
These reactions are usually temporary and signal that the medication is active on the target tissue.
Rarely, more severe problems can develop, including:
If any of these signs appear, seek medical help immediately.
Fluorouracil should be avoided or used with care in the following situations:
A health professional will assess individual risk before prescribing.
Because fluorouracil is applied to the skin, most drug-to-drug interactions are limited. However, consider these points:
For a complete interaction list, refer to the specific product information for Efudex or the generic Fluorouracil formulation.
Store fluorouracil creams at room temperature, away from direct heat or moisture, and keep them out of reach of children. Treatment duration varies; some courses last a few weeks, while others are shorter, depending on the condition and the physician’s plan. Always follow the exact instructions that come with the prescribed product, as formulation strength and application frequency differ between brands. For detailed usage, dosing, and administration, refer to your specific medication’s information.
Antimetabolite: A type of drug that blocks the normal use of building blocks needed for cell growth.
Actinic keratosis: A rough, scaly patch on skin caused by long-term sun exposure, considered pre-cancerous.
Basal cell carcinoma: The most common form of skin cancer, usually developing in the outer skin layer.
Bowen’s disease: Early, non-invasive form of squamous cell skin cancer.
This article offers general educational information about fluorouracil as an active substance used in various medicines. Its purpose is to help patients better understand the ingredient and the conditions it is used to treat. It is not a substitute for professional medical advice or for the specific instructions provided with individual products. Medicines containing fluorouracil may differ in formulation, strength, and directions for use. Always consult the labeling of your particular medication and follow your healthcare provider’s guidance for complete information on proper use, dosage, and safety.
