Zileuton: uses, dosing, side effects & brands
Zileuton is a 5-lipoxygenase inhibitor sold in the U.S. under one brand, for asthma. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- 5-Lipoxygenase Inhibitor
- Treats
- Asthma
- Available as
- Tablet
- Sold as
- Zyflo
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- What the pharmacy pays
- about $61 for a 30-count supply — not your price
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How zileuton is dosed
From the FDA label for Zyflo (application NDA020471). Other zileuton products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
The recommended dosage of ZYFLO for the symptomatic treatment of patients with asthma is one 600-mg tablet four times a day for a total daily dose of 2400 mg. For ease of administration, ZYFLO may be taken with meals and at bedtime. Hepatic transaminases should be evaluated prior to initiation of ZYFLO and periodically during treatment (see PRECAUTIONS, Hepatic ).
Zileuton side effects
Clinical Studies : A total of 5542 patients have been exposed to zileuton in clinical trials, 2252 of them for greater than 6 months and 742 for greater than 1 year. Adverse events most frequently occurring (frequency ≥3%) in ZYFLO-treated patients and at a frequency greater than placebo-treated patients are summarized in Table 2. Proportion of Patients Experiencing Adverse Events in Placebo-Controlled Studies in Asthma Less common adverse events occurring at a frequency of greater than 1% and more commonly in ZYFLO-treated patients included: arthralgia, chest pain, conjunctivitis, constipation, dizziness, fever, flatulence, hypertonia, insomnia, lymphadenopathy, malaise, neck pain/rigidity, nervousness, pruritus, somnolence, urinary tract infection, vaginitis, and vomiting. The frequency of discontinuation from the asthma clinical studies due to any adverse event was comparable between ZYFLO (9.7%) and placebo-treated (8.4%) groups. In placebo-controlled clinical trials, the frequency of ALT elevations ≥3xULN was 1.9% for ZYFLO-treated patients, compared with 0.2% for placebo-treated patients. In controlled and uncontrolled trials, one patient developed symptomatic hepatitis with jaundice, which resolved upon discontinuation of therapy. An additional 3 patients with transaminase elevations developed mild hyperbilirubinemia that was less than three times the upper limit of…
Who shouldn’t take zileuton
ZYFLO tablets are contraindicated in patients with: Active liver disease or transaminase elevations greater than or equal to three times the upper limit of normal (≥3xULN) (see PRECAUTIONS, Hepatic ). Hypersensitivity to zileuton or any of its inactive ingredients.
Every zileuton product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Zyflo.
What zileuton pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
Can you crush or split zileuton?
At least one zileutonproduct is labelled to be swallowed whole — crushing an extended-release tablet releases the whole day’s dose at once. Which applies depends on the form you were given.
What each zileuton label says about crushing, splitting and chewingHow long zileuton keeps
No zileuton label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
Does zileuton expire? The in-use limits and storage rules from its labelsZileuton and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for zileuton: levels in milk, effects in breastfed infants, and the drugs it would consider insteadNo published information is available on the use of zileuton during breastfeeding; however, manufacturer's data indicate that the dose in milk is low. An expert guideline considers that leukotriene receptor antagonists can be used during breastfeeding.
National Institute of Child Health and Human Development, record revised July 15, 2024. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about zileuton
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 198 reports naming zileuton, and the FDA flagged 56% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- asthma26 reports
- dyspnoea15 reports
- nausea13 reports
- pneumonia12 reports
- dizziness9 reports
- chronic obstructive pulmonary disease8 reports
- pruritus7 reports
- vomiting7 reports
Read these as a signal, not a rate. A report does not mean zileuton caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 26, 2026.
Related calculators
Frequently asked questions
What is zileuton?
Zyflo (Zileuton) is a 5-lipoxygenase inhibitor used to treat Asthma.
What kind of drug is zileuton?
The FDA classifies zileuton as a 5-lipoxygenase inhibitor. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take zileuton with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run zileuton against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does zileuton come in?
Across the brands we track, zileuton is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic zileuton?
We do not currently list a generic-labelled zileuton product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Zileuton: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/zileuton
- MLA
- “Zileuton: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/zileuton.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for zileuton on DailyMed (NIH) ↗.