What the label lists and what reports show
Fluorouracil side effects
Fluorouracil's FDA label lists its adverse reactions in its own words. FAERS holds 76,948 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is diarrhoea (6,991 reports).
- Generic listed
- Boxed warning
Check it at the source: the fluorouracil FDA label on DailyMed (effective January 19, 2026, Eugia US LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of Tolak Cream?Tolak Cream can cause serious side effects: Skin reactions including possible allergic reactions. Most people using Tolak Cream get skin reactions in the treated areas. You may get skin reactions such as: redness dryness or scaling crusting itching stinging or burning swelling skin loss (erosion) Eye problems. Eye problems have happened with the use of medicines that contain fluorouracil that are applied to the skin. To help prevent getting Tolak Cream in your eyes, or transferring Tolak Cream from another part of your body to your eyes or to another person's eyes: avoid applying Tolak Cream near or around your eyes wash your hands well after you apply Tolak Cream If you accidentally get Tolak Cream in your eyes, or if Tolak Cream is accidentally transferred to another person's eyes, flush eyes with large amounts of water and get medical help as soon as possible. […]
Source: FDA drug label (TOLAK), HILL DERMACEUTICALS, INC., effective September 6, 2022 (SPL set 59de2709-00b8-4f0a-867c-f0dfeb947192), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe following adverse reactions are discussed in more detail in other sections of the labeling: Serious Adverse Reactions or Death from Dihydropyrimidine Dehydrogenase (DPD) Deficiency [see Warnings and Precautions (5.1) ] Cardiotoxicity [see Warnings and Precautions (5.2) ] Hyperammonemic encephalopathy [see Warnings and Precautions (5.3) ] Neurologic toxicity [see Warnings and Precautions (5.4) ] Diarrhea [see Warnings and Precautions (5.5) ] Palmar-plantar erythrodysesthesia (hand-foot syndrome) [see Warnings and Precautions (5.6) ] Myelosuppression [see Warnings and Precautions (5.7) ] Mucositis [see Warnings and Precautions (5.8) ] Increased risk of elevated INR when administrated with warfarin [see Warnings and Precautions (5.9) ] To report SUSPECTED ADVERSE REACTIONS, contact Eugia US LLC at 1-866-850-2876 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. …
Table 1: Incidence of Application Site Adverse Reactions Occurring with 4 Weeks of Tolak Cream Treatment in Clinical Trials 1 and 2
This table is printed in the TOLAK label published by HILL DERMACEUTICALS, INC. of September 6, 2022; the label quoted above does not print one.
| Reaction | Mild, Moderate or Severe | Severe Only | Mild, Moderate or Severe | Severe Only |
|---|---|---|---|---|
| Erythema | 394 (99%) | 174 (44%) | 102 (85%) | 0 (0%) |
| Scaling/ Dryness | 377 (95%) | 94 (24%) | 99 (83%) | 0 (0%) |
| Crusting | 346 (87%) | 87 (22%) | 46 (38%) | 0 (0%) |
| Pruritus | 337 (85%) | 65 (16%) | 46 (38%) | 1 (1%) |
| Stinging/ Burning | 346 (87%) | 101 (25%) | 42 (35%) | 0 (0%) |
| Edema | 275 (69%) | 30 (8%) | 11 (9%) | 0 (0%) |
| Erosions | 271 (68%) | 44 (11%) | 14 (12%) | 0 (0%) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
Source: FDA drug label, Eugia US LLC, effective January 19, 2026 (SPL set 697816ce-dc05-4943-b7f0-2f0b125e93b7), via openFDA; the full label on DailyMed
What do FAERS reports show?
76,948 reports list fluorouracil among the medicines taken, each a report of something that happened, not proof the medicine caused it; 10,861 are coded as a death and 30,820 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 21 reactions below, 8 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Fluorouracil: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions