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Fluorouracil (Topical)

Medically reviewed by Last updated on Sep 13, 2020.


(flure oh YOOR a sil)

Index Terms

  • 5-Fluorouracil
  • 5-FU
  • FU
  • Topical 5-FU
  • Topical Fluorouracil

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Cream, External:

Carac: 0.5% (30 g) [contains methylparaben, polysorbate 80, propylene glycol, propylparaben, trolamine (triethanolamine)]

Efudex: 5% (40 g)

Fluoroplex: 1% (30 g) [contains benzyl alcohol]

Tolak: 4% (40 g) [contains cetyl alcohol, methylparaben, peanut oil, propylparaben]

Generic: 0.5% (30 g); 5% (40 g)

Solution, External:

Generic: 2% (10 mL); 5% (10 mL)

Brand Names: U.S.

  • Carac
  • Efudex
  • Fluoroplex
  • Tolak

Pharmacologic Category

  • Antineoplastic Agent, Antimetabolite
  • Antineoplastic Agent, Antimetabolite (Pyrimidine Analog)
  • Topical Skin Product


Fluorouracil is a pyrimidine antimetabolite that interferes with DNA synthesis by blocking the methylation of deoxyuridylic acid to thymidylic acid; blocks DNA synthesis to prevent cell proliferation of fast growing cells and cause cell death.


~6% of a topical dose is absorbed systemically (5% cream)

Time to Peak

~1 hour following application (4% cream)

Use: Labeled Indications

Actinic or solar keratosis: Management of multiple actinic or solar keratoses

Basal cell carcinoma, superficial (5%): Treatment of superficial basal cell carcinoma when conventional methods are impractical (eg, due to multiple lesions or difficult treatment sites)

Limitations of use: Establish diagnosis of superficial basal cell carcinoma prior to treatment (has not been proven effective in other types of basal cell carcinomas); surgery is preferred with isolated, easily accessible basal cell carcinomas because success with such lesions is almost 100% and the success rate with fluorouracil cream and solution is ~93%.

Off Label Uses

Penile carcinoma (in situ)

Data from a retrospective study, clinical experience, and an international guideline suggest topical fluorouracil may be of benefit in the management of superficial lesions due to in situ penile carcinoma [Alnajjar 2012], [Minhas 2010], [Pizzocaro 2010].

Squamous cell carcinoma (in situ; Bowen disease)

Long-term follow up data from a small, uncontrolled study suggest topical fluorouracil cream may be of benefit as nonsurgical management of squamous cell carcinoma in situ (also known as Bowen disease) [Bargman 2003].


Hypersensitivity to fluorouracil or any component of the formulation; dihydropyrimidine dehydrogenase (DPD) enzyme deficiency; women who are or may become pregnant

Dosing: Adult

Actinic or solar keratosis: Topical:

Cream (0.5%): Apply thin film to lesions once daily for up to 4 weeks, as tolerated

Cream (1%): Apply to lesions twice daily for 2 to 6 weeks

Cream (4%): Apply to lesions once daily for 4 weeks as tolerated

Cream (5%) or solution (2% and 5%): Apply to lesions twice daily for 2 to 4 weeks; complete healing may not be evident for 1 to 2 months following treatment

Basal cell carcinoma, superficial: Topical: Cream (5%) or solution (5%): Apply to affected lesions twice daily for 3 to 6 weeks; treatment may be continued for up to 10 to 12 weeks

Penile carcinoma (in situ) (off-label use; based on limited data): Topical: Cream (5%): Apply to lesion for 12 hours every 48 hours for 28 days (Alnajjar 2012).

Squamous cell carcinoma (in situ; Bowen disease) (off-label use; based on limited data): Topical: Cream (5%): Apply to lesion(s) twice daily for 9 weeks; a repeat course may be applied for recurrences (Bargman 2003).

Dosing: Geriatric

Refer to adult dosing.


Topical: Apply 10 minutes after washing, rinsing, and drying the affected area. Apply a sufficient amount to cover lesions, preferably using a nonmetal applicator or suitable glove.

Cream (4%): Apply after washing, rinsing, and drying the affected area. Apply a sufficient amount to cover lesions of the face, ears, and/or scalp with a thin film, using fingertips to gently massage uniformly into skin.

If applied with fingertip, wash hands immediately after application. Do not cover area with an occlusive dressing. Topical preparations are for external use only; not for ophthalmic, oral, mucous membrane, or intravaginal use.


Store at 15°C to 30°C (59°F to 86°F). Do not freeze.

Drug Interactions

Brivudine [INT]: May enhance the adverse/toxic effect of Fluorouracil (Topical). Avoid combination

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.


Dermatologic: Application site scaling (≤95%), application site dryness (70% to ≤95%), stinging of the skin (application site: ≤87%), skin erosion (application site: 25% to 68%)

Local: Application site erythema (90% to 99%), application site reaction (92% to 97%; crusting: 87%), application site burning (60% to ≤87%), application site pruritus (85%), application site edema (14% to 69%), application site pain (31% to 61%)

1% to 10%:

Central nervous system: Headache (4%)

Dermatologic: Skin irritation (1% to 2%)

Infection: Common cold (5%)

Ophthalmic: Eye irritation (3% to 7%; burning, watering, sensitivity, stinging, itching)

Respiratory: Sinusitis (5%)

<1%, postmarketing, and/or case reports: Allergic contact dermatitis, alopecia, anxiety, bullous pemphigoid, burning sensation of skin, conjunctival irritation, conjunctivitis, corneal disease, eosinophilia, eye irritation, herpes simplex infection, hyperpigmentation, ichthyosis, inflammation, insomnia, irritability, lacrimation, leukocytosis, lymphocytic leukemia, medicine-like taste, muscle tenderness, nasal discomfort, pain, pancytopenia, pruritus, scarring, skin blister, skin irritation, skin neoplasm (nonmelanoma), skin photosensitivity, skin rash, skin tenderness, stomatitis, suppuration, swelling, swelling of eye, telangiectasia, thrombocytopenia, toxic granulations, ulcer, urticaria


Concerns related to adverse effects:

• Hypersensitivity: Delayed-type hypersensitivity reactions, including allergic contact dermatitis, have been reported. Severe pruritus or eczema (at the application site or at a distant site) may be indicative of hypersensitivity. Patch testing may not be useful in the evaluation of these reactions. Discontinue immediately for signs of hypersensitivity.

• Local skin reactions: When applied to a lesion, erythema followed by vesiculation, desquamation, erosion and reepithelialization occurs. Local reactions and alterations in skin appearance may persist for several weeks after discontinuation. Bruising, burning, crusting, dryness, edema, irritation, pain, pruritus, scaling, scarring, soreness, stinging, and ulceration may commonly result from topical therapy. Increased absorption through ulcerated or inflamed skin is possible.

• Ocular adverse reactions: Corneal and conjunctival disorders have occurred with topical fluorouracil; avoid application to the periocular area.

• Photosensitivity: Topical fluorouracil is associated with photosensitivity, including severe sunburn. Avoid prolonged exposure to sunlight or UV irradiation during treatment; reaction intensity may be increased.

Disease-related concerns:

• Dihydropyrimidine dehydrogenase enzyme deficiency: Dihydropyrimidine dehydrogenase (DPD) enzyme deficiency may result in increased cytotoxic activity and severe toxicity with topical fluorouracil. Life-threatening systemic toxicity has been reported with topical fluorouracil in a patient with DPD enzyme deficiency; signs/symptoms included bloody diarrhea, stomatitis, esophagus, stomach, and small bowel inflammation, severe abdominal pain, vomiting, chills, fever, erythematous skin rash, neutropenia, and thrombocytopenia. Discontinue if signs of DPD deficiency develop.

Dosage form specific issues:

• Benzyl alcohol and derivatives: Some dosage forms may contain benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity ("gasping syndrome") in neonates; the "gasping syndrome" consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension and cardiovascular collapse (AAP 1997; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol with caution in neonates. See manufacturer's labeling.

• Peanut oil: Some dosage forms contain peanut oil.

• Polysorbate 80: Some dosage forms may contain polysorbate 80 (also known as Tweens). Hypersensitivity reactions, usually a delayed reaction, have been reported following exposure to pharmaceutical products containing polysorbate 80 in certain individuals (Isaksson 2002; Lucente 2000; Shelley 1995). Thrombocytopenia, ascites, pulmonary deterioration, and renal and hepatic failure have been reported in premature neonates after receiving parenteral products containing polysorbate 80 (Alade 1986; CDC 1984). See manufacturer's labeling.

• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated with hyperosmolality, lactic acidosis, seizures and respiratory depression; use caution (AAP 1997; Zar 2007). See manufacturer's labeling.

Other warnings/precautions:

• Appropriate use: Avoid application to mucous membranes due to potential for local inflammation and ulceration. Occlusive dressings may increase the severity of inflammation in nearby skin areas (a porous gauze dressing may be applied for cosmetic reasons without increase in reaction). Avoid eyelids, eyes, and periocular area when applying. Wash hands well following application; if ocular exposure occurs, flush with large amounts of water.

Reproductive Considerations

Use is contraindicated in patients who may become pregnant.

Females of reproductive potential should use effective contraception during treatment and for 1 month after the final application of topical fluorouracil.

Pregnancy Considerations

Use is contraindicated in patients who are pregnant.

Adverse effects, including ventricular septal defect and miscarriage, have been reported following topical application of fluorouracil products to mucous membranes in pregnant patients.

Patient Education

What is this drug used for?

• It is used to treat a precancerous skin problem called actinic keratosis.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Burning

• Dry skin

• Swelling

• Redness

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Abdominal pain

• Bloody diarrhea

• Vomiting

• Mouth irritation

• Mouth sores

• Chills

• Sore throat

• Bruising

• Bleeding

• Severe loss of strength and energy

• Severe skin irritation

• Severe diarrhea

• Vision changes

• Eye pain

• Severe eye irritation

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.