Topical antimetabolite + keratolytic Pregnancy: Contraindicated in pregnancy and breastfeeding. No data on topical fluorouracil in pregnant women; systemically administered fluorouracil is teratogenic in animals and salicylic acid can adversely influence pregnancy outcome in rodents. It is unknown whether fluorouracil or its metabolites are excreted in human milk after topical application and a risk to the suckling child cannot be excluded

Fluorouracil with salicylic acid

Brand names: Actikerall

This is a combination topical solution of the antimetabolite fluorouracil with the keratolytic salicylic acid, used to treat actinic (solar) keratoses.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Apply once daily to the affected area (up to 25 cm²)

Route: Cutaneous (topical solution, applied with the brush applicator)

Frequency: Once daily

Max: Total area of skin treated at any one time must not exceed 25 cm² (5 cm x 5 cm); treat for up to a maximum of 12 weeks

Source: eMC SPC for Actikerall 5 mg/g + 100 mg/g cutaneous solution (fluorouracil with salicylic acid), §4.2 — indication: actinic keratosis. Continue until the lesions have completely cleared or for up to a maximum of 12 weeks. If severe side effects occur, reduce the frequency of application to three times per week until the side effects improve. If areas of skin with a thin epidermis are treated, apply less frequently and monitor the course of therapy more often. Response can be seen as early as four weeks; response increases over time and data are available for treatment up to 12 weeks. Complete healing or optimal therapeutic effect may not be evident for up to eight weeks after treatment cessation — treatment should be continued even if response is not apparent after the first four weeks. Efficacy of retreatment of recurrent lesions has not been formally measured in clinical trials. Method of administration: cutaneous use only; there is experience in treating up to ten single lesions at the same time, and multiple actinic keratoses with surrounding skin may be treated simultaneously where field treatment is preferred. Wipe the brush off in the neck of the bottle to avoid overloading it, but leave enough product for film formation on drying. Do not cover the treated area after application; let the solution dry to form a film. Remove the existing film by gently peeling it off before each reapplication (warm water may help). Do not apply to hairy skin (risk of conglutination of hair) — consider a shave or other hair removal beforehand. Elderly: no dose adjustment is necessary. PAEDIATRIC: the SPC states there is no relevant use of Actikerall in the paediatric population for the indication of actinic keratosis — no paediatric dose is given; verify against a children's formulary if paediatric use is being considered. Must not be used on bleeding lesions; must not come into contact with the eyes or mucous membranes; no experience in basal cell carcinoma or Bowen's disease, which should not be treated with this product. Flammable — keep away from fire, naked flames, lit cigarettes and devices such as hairdryers.

Dose adjustments

Renal

No dose adjustment given — contraindicated: must not be used to treat patients with renal insufficiency (§4.3)

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substances or to any of the excipients
Pregnancy and lactation
Renal insufficiency — must not be used to treat patients with renal insufficiency
Concomitant use with brivudine, sorivudine and analogues (potent DPD inhibitors)
Must not be allowed to come into contact with the eyes or mucous membranes

Side effects

Very common — application site reactions: erythema, inflammation, irritation (including burning), pain, pruritus
Common — application site bleeding, erosion and scab; skin exfoliation
Common — headache
Uncommon — application site oedema, ulcer, dermatitis
Uncommon — dry eye, eye pruritus, increased lacrimation
Whitish discoloration and scaling of the skin (strong softening effect on the stratum corneum), and salicylic acid-related contact allergic reactions with itching, reddening and small blisters that may extend beyond the area of application

Interactions

Brivudine, sorivudine and analogous antiviral nucleoside analogues — potent inhibitors of dihydropyrimidine dehydrogenase (DPD); may cause a drastic increase in plasma concentrations of fluorouracil or other fluoropyrimidines with an associated increase in toxicity (contraindicated concomitantly)
An interval of at least 4 weeks should be observed between the use of fluorouracil and brivudine, sorivudine or analogues
Accidental administration of brivudine/sorivudine-type nucleoside analogues during fluorouracil treatment requires effective measures to reduce fluorouracil toxicity; hospital admission may be indicated, with protection from systemic infections and dehydration

Clinical monograph

How it works

Fluorouracil inhibits thymidylate synthase to disrupt DNA synthesis in rapidly dividing atypical keratinocytes, while salicylic acid softens and removes hyperkeratotic surface scale to enhance penetration.

Prescribing in practice

Expect an intended local inflammatory reaction (erythema, erosion, crusting) at treated lesions; apply only to the keratoses themselves, protecting surrounding healthy skin, and avoid eyes, mucous membranes and broken skin.
It is contraindicated in pregnancy and breast-feeding because of the cytotoxic fluorouracil component.
Avoid use in patients with known dihydropyrimidine dehydrogenase deficiency, in whom systemic toxicity risk is increased.

Monitoring

Review treated lesions for the expected reaction and for healing after the course, and reassess any lesion that fails to resolve to exclude malignancy.

Counselling the patient

A localised reaction with redness and soreness is expected and indicates the treatment is working.
Apply precisely to the rough patches only and keep it away from the eyes, lips and normal skin.
Protect treated areas from sunlight during and after the course.

Evidence & guidelines

Topical field therapies including fluorouracil are recommended options for actinic keratosis in line with established dermatology guidance.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways