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What the label lists and what reports show

Zileuton side effects

Zileuton's FDA label: “Most common adverse reactions (≥5%) included: sinusitis, nausea, and pharyngolaryngeal pain.” FAERS holds 641 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 dyspnoea (52 reports).

  • Generic listed

Check it at the source: the zileuton FDA label on DailyMed (effective July 29, 2022, Strides Pharma Science Limited); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

Most common adverse reactions (≥5%) included: sinusitis, nausea, and pharyngolaryngeal pain.

From the label: adverse reactions, continued

Hepatotoxicity: Elevations of one or more hepatic function enzymes and bilirubin may occur during zileuton extended-release tablets therapy [see Warnings and Precautions (5)]. The most commonly occurring adverse reactions (≥5%) with zileuton extended-release tablets are sinusitis, nausea, and pharyngolaryngeal pain. Most common adverse reactions (≥5%) included: sinusitis, nausea, and pharyngolaryngeal pain. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Strides Pharma Inc at 1-877-244-9825 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Short-Term Clinical Studies Experience The safety data described below reflect exposure to zileuton extended-release tablets in 199 patients for 12 weeks duration. In a 12-week, randomized, double-blind, placebo-controlled trial in adults and adolescents 12 years of age and older with asthma, patients received zileuton extended-release tablets two 600 mg tablets (n=199) or placebo (n=198) twice daily by mouth. Eighty-three percent of patients were white, 48% were male, and the mean age was 34 years. Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. …

Source: FDA drug label, Strides Pharma Science Limited, effective July 29, 2022 (SPL set a826d16f-df07-447b-b050-b9a02ea1f89e), via openFDA; the full label on DailyMed

What do FAERS reports show?

641 reports list zileuton among the medicines taken, each a report of something that happened, not proof the medicine caused it; 22 are coded as a death and 164 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 19 reactions below, 7 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

  • Asthma (a use or a product term, not a reaction)76
  • Dyspnoea52
  • Drug Ineffective (a use or a product term, not a reaction)48
  • Nausea (named in the label)40
  • Off Label Use (a use or a product term, not a reaction)38
  • Pneumonia33
  • Cough31
  • Fatigue30
  • Headache (named in the label)26
  • Product Use In Unapproved Indication (a use or a product term, not a reaction)26
  • Malaise23
  • Wheezing23
  • Anaphylactic Reaction22
  • Pruritus22
  • Sinusitis (named in the label)22
  • Arthralgia21
  • Urticaria21
  • Pain20
  • Chest Discomfort19
  • Diarrhoea (named in the label)19
  • Rash (named in the label)19
  • Product Dose Omission Issue (a use or a product term, not a reaction)18
  • Vomiting (named in the label)18
  • Condition Aggravated (a use or a product term, not a reaction)17
  • Hypersensitivity (named in the label)17

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Zileuton: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions