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Fluorouracil Side Effects

The most commonly reported side effects of fluorouracil include diarrhoea, neutropenia, and nausea, based on 86,511 FDA adverse event reports from 2004 to 2025. 2.6% of reports found the drug to be ineffective.

Fluorouracil side effects

Percentages show how often each reaction appears relative to total reports for fluorouracil.

1
Diarrhoea7.4%6,438
2
Neutropenia5.7%4,963
3
Nausea5.4%4,677
4
Off Label Use4.5%3,877
5
Vomiting4.1%3,552
6
Neuropathy Peripheral3.8%3,315
7
Disease Progression3.6%3,147
8
Fatigue3.6%3,074
9
Thrombocytopenia3.4%2,926
10
Pyrexia3.1%2,653
11
Febrile Neutropenia3.0%2,563
12
Anaemia2.9%2,501
13
Asthenia2.9%2,479
14
Death2.8%2,405
15
Drug Ineffective2.6%2,244

These are voluntary reports and do not establish that fluorouracil caused these reactions.

Report severity

94.3%Serious81,537 reports
40.0%Hospitalizations34,635 reports
14.7%Fatal12,743 reports

Seriousness is determined by the reporter, not by OpenClaim.

Fluorouracil drug interactions

Other drugs that appear in adverse event reports alongside fluorouracil. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Oxaliplatin39.9%34,534
2
Irinotecan-hydrochloride24.4%21,090
3
Bevacizumab20.2%17,440
4
Levoleucovorin12.4%10,763
5
Leucovorin-calcium10.2%8,845
6
Cisplatin8.5%7,346
7
Docetaxel7.9%6,872
8
Cetuximab7.2%6,267
9
Panitumumab6.7%5,755
10
Epirubicin-hydrochloride6.4%5,542
11
Cyclophosphamide6.3%5,459
12
Capecitabine5.2%4,484
13
Calcium5.1%4,433
14
Trastuzumab3.5%3,038
15
Paclitaxel3.5%2,996

Taken alongside

1
Oxaliplatin7.6%6,617
2
Dexamethasone7.4%6,395
3
Levoleucovorin6.4%5,532
4
Irinotecan-hydrochloride5.9%5,079
5
Ondansetron5.5%4,790
6
Acetaminophen3.8%3,282
7
Leucovorin-calcium3.7%3,167
8
Calcium3.4%2,915
9
Pantoprazole-sodium2.9%2,536
10
Aspirin2.5%2,134
11
Omeprazole2.4%2,119
12
Loperamide-hydrochloride2.4%2,071
13
Cyclophosphamide2.2%1,923
14
Amlodipine2.1%1,837
15
Bevacizumab2.1%1,785

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports fluorouracil side effects

39.3% of fluorouracil adverse event reports involve female patients and 46.4% involve male patients. The largest age group is adult at 55%. These figures reflect who reports side effects, not underlying risk.

Sex

Female39.3%
Male46.4%
Unknown14.3%

Age group

< 20.5%
2–110.3%
12–170.3%
18–6454.7%
65+44.3%

What is fluorouracil used for

Conditions and purposes for which patients were taking fluorouracil when the adverse event was reported.

Abdominal NeoplasmAccidental ExposureAccidental Exposure To ProductAcinar Cell Carcinoma Of PancreasAcneActinic CheilitisActinic KeratosisAcute Lymphocytic LeukaemiaAcute Lymphocytic Leukaemia RecurrentAcute Myeloid LeukaemiaAcute Myeloid Leukaemia (in Remission)Acute Promyelocytic LeukaemiaAdenocarcinomaAdenocarcinoma GastricAdenocarcinoma Metastatic

Showing 15 of 1,415 indications

Fluorouracil brand names and reporting trend

Fluorouracil is sold under the brand name Adrucil.

Brand names

Adrucil118,614

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking fluorouracil with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.