Fluorouracil

Mechanism-of-action classes: Nucleic Acid Synthesis Inhibitors; Thymidylate Synthetase Inhibitors.

• Fluorouracil Cream is recommended for the topical treatment of multiple actinic or solar keratoses. In the 5% strength, it is also useful in the treatment of superficial basal cell carcinomas when conventional methods are impractical, such as with multiple lesions or difficult treatment sites.

• Fluorouracil Cream may cause fetal harm when administered to a pregnant woman. There are no adequate and well-controlled studies in pregnant women with either the topical or the parenteral forms of fluorouracil.contraindicated

When Fluorouracil Cream is applied to a lesion, a response occurs with the following sequence: erythema, usually followed by vesiculation, desquamation, erosion, and re-epithelialization. Fluorouracil Cream should be applied preferably with a nonmetal applicator or suitable glove. If Fluorouracil Cream is applied with the fingers, the hands should be washed immediately afterward. Actinic or Solar Keratosis Apply cream twice daily in an amount sufficient to cover the lesions. Medication should be continued until the inflammatory response reaches the erosion stage, at which time use of the drug should be terminated. The usual duration of therapy is from 2 to 4 weeks. Complete healing of the lesions may not be evident for 1 to 2 months following cessation of Fluorouracil Cream therapy. Superficial Basal Cell Carcinomas Only the 5% strength is recommended. Apply cream twice daily in an amount sufficient to cover the lesions. Treatment should be continued for at least 3 to 6 weeks. Therapy may be required for as long as 10 to 12 weeks before the lesions are obliterated. As in any neoplastic condition, the patient should be followed for a reasonable period of time to determine if a cure has been obtained.

Application to mucous membranes should be avoided due to the possibility of local inflammation and ulceration. Additionally, cases of miscarriage and a birth defect (ventricular septal defect) have been reported when Fluorouracil Cream was applied to mucous membrane areas during pregnancy. Occlusion of the skin with resultant hydration has been shown to increase percutaneous penetration of several topical preparations. If any occlusive dressing is used in treatment of basal cell carcinoma, there may be an increase in the severity of inflammatory reactions in the adjacent normal skin. A porous gauze dressing may be applied for cosmetic reasons without increase in reaction. Exposure to ultraviolet rays should be minimized during and immediately following treatment with Fluorouracil Cream because the intensity of the reaction may be increased. Patients should discontinue therapy with Fluorouracil Cream if symptoms of DPD enzyme deficiency develop (see CONTRAINDICATIONS ). Rarely, life-threatening toxicities such as stomatitis, diarrhea, neutropenia, and neurotoxicity have been reported with intravenous administration of fluorouracil in patients with DPD enzyme deficiency. One case of life-threatening systemic toxicity has been reported with the topical use of Fluorouracil Cream in a patient with DPD enzyme deficiency. Symptoms included severe abdominal pain, bloody diarrhea, vomiting, fever, and chills. Physical examination revealed stomatitis, erythematous skin rash, neutropenia, thrombocytopenia, inflammation of the esophagus, stomach, and small bowel.

The most frequent adverse reactions to Fluorouracil Cream occur locally and are often related to an extension of the pharmacological activity of the drug. These include burning, crusting, allergic contact dermatitis, pruritus, scarring, rash, soreness, and ulceration. Ulcerations, other local reactions, cases of miscarriage, and a birth defect (ventricular septal defect) have been reported when Fluorouracil Cream was applied to mucous membrane areas. Leukocytosis is the most frequent hematological side effect. Although a causal relationship is remote, other adverse reactions which have been reported infrequently are: Central Nervous System: Emotional upset, insomnia, irritability. Gastrointestinal: Medicinal taste, stomatitis. Hematological: Eosinophilia, thrombocytopenia, toxic granulation. Integumentary: Alopecia, blistering, bullous pemphigoid, discomfort, ichthyosis, scaling, suppuration, swelling, telangiectasia, tenderness, urticaria, skin rash. Special Senses: Conjunctival reaction, corneal reaction, lacrimation, nasal irritation. Miscellaneous: Herpes simplex. To report SUSPECTED ADVERSE REACTIONS contact Mayne Pharma at 1-844-825-8500 or FDA at 1-800-FDA-1088 or www.FDA.gov/medwatch.

Pregnancy See CONTRAINDICATIONS .

There have been no reports of overdosage with Fluorouracil Cream. The oral LD 50 for the 5% topical cream was 234 mg/kg in rats and 39 mg/kg in dogs. These doses represented 11.7 and 1.95 mg/kg of fluorouracil, respectively. The topical application of the 5% cream to rats yielded an LD 50 of greater than 500 mg/kg.

• Jul 29, 1970NDANDA016831Extrovis
• Sep 30, 1998ANDAANDA040278Fresenius Kabi Usa
• Sep 30, 1998ANDAANDA040279Fresenius Kabi Usa
• Oct 27, 2000NDANDA020985Extrovis
• Nov 5, 2003ANDAANDA076526Taro
• Apr 26, 2007ANDAANDA040743Accord Hlthcare
• Sep 18, 2015NDANDA022259Hill Dermaceuticals
• Feb 20, 2026NDANDA220201Avyxa Holdings

1. 1Diarrhoea6,8429.1%
2. 2Neutropenia5,0756.8%
3. 3Nausea4,8566.5%
4. 4Vomiting3,9055.2%
5. 5Off Label Use3,4784.6%
6. 6Neuropathy Peripheral3,2394.3%
7. 7Disease Progression3,1974.3%
8. 8Fatigue3,0904.1%
9. 9Pyrexia3,0044.0%
10. 10Thrombocytopenia2,9163.9%
11. 11Febrile Neutropenia2,8373.8%
12. 12Asthenia2,5333.4%
13. 13Anaemia2,4793.3%
14. 14Drug Ineffective2,1742.9%
15. 15Malignant Neoplasm Progression2,0892.8%

Recent PubMed references pinned to Fluorouracil as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Pharmacokinetics of 5-Fluorouracil in Patients Treated With Capecitabine Carrying the c.1236G>A DPYD Variant Allele.
  JCO precision oncology · 2026 · Heersche N, Knikman JE, Deenen MJ, et al.
  PMID 42258784DOI 10.1200/PO-26-00090
• Fosnetupitant for long-delayed chemotherapy-induced nausea and vomiting in oxaliplatin-based regimens: a prospective observational study (LODEC-N).
  Cancer chemotherapy and pharmacology · 2026 · Iimura Y, Iihara H, Aoyama T, et al.
  PMID 42257726DOI 10.1007/s00280-026-04912-x
• [Research on 5-Fluorouracil-Induced Injury in Human Intestinal Organoids].
  Zhongguo shi yan xue ye xue za zhi · 2026 · Fang JR, Li XT, Zhu H, et al.
  PMID 42227455DOI 10.19746/j.cnki.issn1009-2137.2026.02.036
• Does the Duration of FLOT Infusion Change the Outcome of Perioperative Treatment for Gastric Cancer? Comparing 24- and 48-h Infusions.
  Medicina (Kaunas, Lithuania) · 2026 · Demir H, Yıldız C, İlhan Y, et al.
  PMID 42195240DOI 10.3390/medicina62050987
• Real-World Effectiveness of Capecitabine and Temozolomide Across Endocrine and Neuroendocrine Neoplasm Subtypes (ENENs): A Population-Based Cohort Study from Alberta, Canada (2011-2021).
  Current oncology (Toronto, Ont.) · 2026 · Aleksi A, Jobin KD, Hannouf MB, et al.
  PMID 42187606DOI 10.3390/curroncol33050289
• Real-World Efficacy of Metronomic Chemotherapy in Advanced Breast Cancer Across Molecular Subtypes.
  Cancer medicine · 2026 · Zhou H, Chen L, Lu Q, et al.
  PMID 42187010DOI 10.1002/cam4.71961
• Beyond conventional 5-Fluorouracil: Recent medicinal chemistry strategies to enhance its anticancer efficacy.
  European journal of medicinal chemistry · 2026 · Mocka S, Modica MN, Pittalà V, et al.
  PMID 42176655DOI 10.1016/j.ejmech.2026.118967
• Fulvestrant versus capecitabine as maintenance therapy in hormone receptor-positive, HER2-negative metastatic breast cancer after first-line chemotherapy (FAMILY): a multicenter, open-label, randomized, phase 3 trial.
  Signal transduction and targeted therapy · 2026 · Wu W, Yang Y, Chen H, et al.
  PMID 42168151DOI 10.1038/s41392-026-02720-6

The 10 most recently updated of 4,982 ClinicalTrials.gov registrations naming Fluorouracil as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Substudy 06E: Umbrella Study of Combination Therapies in Esophageal Cancer (MK-3475-06E/KEYMAKER-U06)
  Recruiting · Phase 1 · Phase 2 · Interventional · 298 enrolled · Merck Sharp & Dohme LLC
  NCT06780111updated 2026-06-12
• Targeted Therapy Directed by Genetic Testing in Treating Patients With Locally Advanced or Advanced Solid Tumors, The ComboMATCH Screening Trial
  Recruiting · Phase 2 · Interventional · 2,900 enrolled · National Cancer Institute (NCI)
  NCT05564377updated 2026-06-12
• A Study to Assess Intravenous (IV) Telisotuzumab Adizutecan in Combination With Fluorouracil, Folinic Acid, and Oxaliplatin (FOLFOX) Compared to Standard of Care in Adult Participants With First-Line Metastatic Pancreatic Ductal Adenocarcinoma
  Recruiting · Phase 2 · Phase 3 · Interventional · 900 enrolled · AbbVie
  NCT07490301updated 2026-06-12
• A Study of CHS-114 (Tagmokitug) in Combination With Toripalimab and/or Other Treatments in Participants With Advanced Solid Tumors
  Recruiting · Phase 1 · Interventional · 154 enrolled · Coherus Oncology, Inc.
  NCT06657144updated 2026-06-12
• ctHPVDNA Response-Adapted Chemoradiation +/- Retifanlimab Treatment in Locally-Advanced Anal Cancer
  Not yet recruiting · Phase 2 · Interventional · 33 enrolled · Jennifer Dorth
  NCT07425054updated 2026-06-12
• Paclitaxel, Carboplatin and Cetuximab (PCC) With Cetuximab, Docetaxel, Cisplatin and Fluorouracil (C-TPF) in Previously Untreated Patients With Locally Advanced Head and Neck Squamous Cell Carcinoma
  Active not recruiting · Phase 2 · Interventional · 128 enrolled · M.D. Anderson Cancer Center
  NCT01154920updated 2026-06-12
• PhII Randomized CAPecitabine + ELAcestrant vs. Capecitabine Alone in ER+ Breast Cancer (CAPELA)
  Recruiting · Phase 2 · Interventional · 297 enrolled · Kristina A. Fanucci
  NCT07222215updated 2026-06-12
• Neratinib In Combination With Chemotherapy/Trastuzumab/Pembrolizumab In HER2 Gastroesophageal Cancer
  Active not recruiting · Phase 2 · Interventional · 8 enrolled · H. Lee Moffitt Cancer Center and Research Institute
  NCT06109467updated 2026-06-12
• A Clinical Study of Sacituzumab Tirumotecan (Sac-TMT, MK-2870) in People With Breast Cancer (MK-2870-032)
  Recruiting · Phase 3 · Interventional · 2,400 enrolled · Merck Sharp & Dohme LLC
  NCT06966700updated 2026-06-12
• A Study to Evaluate the Adverse Events, and Efficacy of Intravenous (IV) of Telisotuzumab Adizutecan in Combination With IV Oxaliplatin, Fluorouracil, Folinic Acid/Leucovorin, Bevacizumab, Panitumumab in Adult Participants With Metastatic Colorectal Cancer
  Recruiting · Phase 2 · Interventional · 390 enrolled · AbbVie
  NCT06820463updated 2026-06-12

CPIC-curated drug–gene pairs for Fluorouracil. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

• DPYDCPIC AClinPGx 1AFDA label: Testing Required
  DPYD and Fluoropyrimidines
• GSTP1CPIC D (provisional)ClinPGx 3
• NQO1CPIC D (provisional)ClinPGx 3
• TYMSCPIC D (provisional)ClinPGx 3
• UMPSCPIC D (provisional)ClinPGx 3

Frequently asked questions

How does Fluorouracil work?

Mechanism-of-action classes: Nucleic Acid Synthesis Inhibitors; Thymidylate Synthetase Inhibitors.

What is Fluorouracil used for?

According to FDA labeling, Fluorouracil carries indications including: Fluorouracil Cream is recommended for the topical treatment of multiple actinic or solar keratoses. In the 5% strength, it is also useful in the treatment of superficial basal cell carcinomas when conventional methods are impractical, such as with multiple lesions or difficult treatment sites.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Fluorouracil?

Fluorouracil is classified as Pyrimidine analogues, Nucleoside Metabolic Inhibitor, Nucleic Acid Synthesis Inhibitors, Thymidylate Synthetase Inhibitors, Decreased DNA Integrity, Decreased RNA Integrity.

What are the brand names for Fluorouracil?

Fluorouracil is marketed under brand names including Adrucil, Carac, Efudex, Favlyxa, Fluoroplex, Tolak.

What are the contraindications for Fluorouracil?

Fluorouracil labeling lists contraindications including: Fluorouracil Cream may cause fetal harm when administered to a pregnant woman. There are no adequate and well-controlled studies in pregnant women with either the topical or the parenteral forms of fluorouracil.. Always consult the full prescribing information and a clinician.