Formulary
Fluorouracil: Indications, Dosing, Side Effects and Interactions
Fluorouracil, an analogue of the pyrimidine uracil, is a cytostatic that inhibits DNA and RNA synthesis, resulting in growth inhibition of malignant and...
MedNext Academy | 4 min read
Fluorouracil: Indications, Dosing, Side Effects and Interactions
Fluorouracil, an analogue of the pyrimidine uracil, is a cytostatic that inhibits DNA and RNA synthesis, resulting in growth inhibition of malignant and...
Drug action
Fluorouracil, an analogue of the pyrimidine uracil, is a cytostatic that inhibits DNA and RNA synthesis, resulting in growth inhibition of malignant and pre-malignant cells.
Indications and dose
**Solid tumours [including gastro-intestinal tract cancers and breast cancer] (specialist use only),Colorectal cancer (specialist use only)**
- **Adult** (By Intravenous Injection, Or By Intravenous Infusion, Or By Intra-Arterial Infusion): Specialist indication - access specialist resources for dosing information.
**Superficial malignant and pre-malignant skin lesions [using 5% cream]**
- **Adult** (To The Skin): Apply 1-2 times a day for 3-4 weeks (usual duration of initial therapy), to be applied thinly to the affected area, max. area of skin 500 cm 2 (e.g. 23 cm 23 cm) treated at one time, alternative regimens may be used in some settings.
**Actinic keratosis on face, ears, and/or scalp [using 4% cream]**
- **Adult** (To The Skin): Apply once daily for 4 weeks (as tolerated), to be applied thinly to the affected area.
Cautions
With systemic use History of heart disease; partial dihydropyrimidine dehydrogenase deficiency-consult product literature With topical use Avoid contact with eyes and mucous membranes; dihydropyrimidine dehydrogenase deficiency; do not apply to open wounds or damaged skin
Contraindications
With systemic use Bone marrow depression (after treatment with radiotherapy or other antineoplastic agents); complete or near complete absence of dihydropyrimidine dehydrogenase activity (increased risk of severe, life-threatening, or fatal toxicity)-consult product literature; serious infections
Side effects
General side-effects: Common or very common Alopecia; diarrhoea; increased risk of infection; mucositis; nausea; skin reactions; vomiting Uncommon Dizziness; eye disorders; eye inflammation; headache; photosensitivity reaction Rare or very rare Fever Specific side-effects: Common or very common With parenteral use Agranulocytosis; anaemia; anal inflammation; appetite decreased; asthenia; bone marrow disorders; bronchospasm; gastrointestinal disorders; haemorrhage; hand and foot syndrome (long term use); healing impaired; immunosuppression; ischaemic heart disease; leucopenia; malaise; neutropenia; stomatitis; thrombocytopenia With topical use Eye discomfort Uncommon With parenteral use Arrhythmias; cardiac inflammation; cardiogenic shock; cardiomyopathy congestive; dehydration; drowsiness; euphoric mood; heart failure; hepatic disorders; hypotension; movement disorders; myocardial infarction; nail discolouration; nail disorders; nerve disorders; ovulation disorder; parkinsonism; sepsis; spermatogenesis disorder; vision disorders With topical use Insomnia; nasal discomfort; oral disorders Rare or very rare With parenteral use Biliary sclerosis; cardiac arrest; cerebral ischaemia; cholecystitis; coma; confusion; embolism and thrombosis; encephalopathy; muscle weakness; peripheral vascular disease; renal failure; seizure; speech impairment; sudden cardiac death With topical use Abdominal pain; blood disorder; chills; diarrhoea haemorrhagic; skin ulcer Frequency not known With parenteral use Vein discolouration With topical use Taste altered Side-effects, further information For severe skin discomfort or skin reactions lasting longer than 4 weeks, symptomatic treatment (e.g. emollients or topical corticosteroids) should be offered.
Interactions
**Other interactions (6):**
- The enzyme dihydropyrimidine dehydrogenase (DPD) plays an important role in the breakdown of fluorouracil.
- Antiviral nucleoside analogues such as brivudine and sorivudine may lead to a drastic increase in plasma concentrations of fluorouracil or other fluoropyrimidines and thus an associated increase in...
- For this reason, an interval of at least 4 weeks between the use of fluorouracil and brivudine, sorivudine and analogues should be observed.
- In case of accidental administration of nucleoside analogues such as brivudine and sorivudine to patients who are being treated with fluorouracil, effective measures for reducing fluorouracil...
- Elevated plasma levels of phenytoin leading to symptoms of phenytoin intoxication have been reported with the concomitant administration of systemic fluorouracil and phenytoin.
- There is no evidence for relevant systemic absorption of salicylic acid, however absorbed salicylic acid may interact with methotrexate and sulphonylureas.
Pregnancy
With systemic use: Avoid (teratogenic). See also Pregnancy and reproductive function in Cytotoxic drugs . With topical use: Manufacturers advise avoid (teratogenic).
Breast feeding
With systemic use: Discontinue breast-feeding. With topical use: Specialist sources indicate unlikely to affect breast-fed infants due to minimal absorption through the skin; avoid application to breast or nipple and ensure infant does not come in contact with treated area.
Hepatic impairment
With intra-arterial use or intravenous use: Manufacturer advises caution (increased risk of hyperammonaemia and hyperammonaemic encephalopathy). Dose adjustments With intra-arterial use or intravenous use: Manufacturer advises consider dose reduction.
Renal impairment
With intra-arterial use or intravenous use: Manufacturer advises caution (increased risk of hyperammonaemia and hyperammonaemic encephalopathy). Dose adjustments With intra-arterial use or intravenous use: Manufacturer advises consider dose reduction.
Medicinal forms
Solution,Solution,Solution,Cream
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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