Prescription medicine
Zileuton Brand names: Zyflo
Zileuton (Zyflo) is a prescription medicine with an FDA approval on record since 1996. FDA's NDC Directory lists it from 5 generic labelers, and pharmacies paid $2.05 per zileuton ER 600 mg tablet in the October 7, 2026 NADAC survey.
- Generic listed
Check it at the source: the zileuton FDA label on DailyMed (effective July 29, 2022, Strides Pharma Science Limited); the NDA 20471 record on Drugs@FDA; every zileuton label on DailyMed.
Highlights of the record
FDA label of July 29, 2022; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026; NADAC October 7, 2026
Used for
From the label: indications and usageZileuton extended-release tablets are indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older.
Forms and strengths
- 600 mg
Film-coated extended-release tablet; multilayer extended-release tablet; tablet; extended-release tablet.
On the market
- Earliest approval on file
- December 9, 1996 Zyflo, Chiesi; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 6 first March 17, 2017; 4 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 6 of which 5 under generic applications, 1 under brand applications, repackagers included
Supply and safety
- Pharmacy cost (NADAC)
- $2.05 per tablet Zileuton ER 600 mg tablet
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- 2 since 2019 0 Class I among all firms' recalls; latest June 10, 2022
- FAERS reports
- 641 through July 30, 2026
What is zileuton used for?
From the label: indications and usageZileuton extended-release tablets are indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older. Zileuton extended-release tablets are not indicated for use in the reversal of bronchospasm in acute asthma attacks. Therapy with zileuton extended-release tablets can be continued during acute exacerbations of asthma. Zileuton extended-release tablets are a leukotriene synthesis inhibitor indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older. (1) Do not use zileuton extended-release tablets to treat an acute asthma attack.
Conditions named in the indications of zileuton's FDA labels, with every medicine labeled for each:
FDA pharmacologic class: 5-Lipoxygenase Inhibitor.
Source: FDA drug label (Zileuton), Strides Pharma Science Limited, effective July 29, 2022 (SPL set a826d16f-df07-447b-b050-b9a02ea1f89e), via openFDA; the full label on DailyMed
Is there a generic for zileuton (Zyflo)?
The FDA approved the first generic zileuton on March 17, 2017. 6 generic applications are approved; 4 of them carry a current (not discontinued) marketing status in Drugs@FDA; that status is not evidence that the generic is on sale.
FDA's NDC Directory lists zileuton from 5 labelers under a generic (ANDA) application and from 1 brand labeler. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it.
- 1996 earliest approval on file
- 2017 first generic approved
- red ticks recalls
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
What do pharmacies pay for zileuton (Zyflo)?
In CMS's NADAC survey of October 7, 2026, pharmacies paid $2.05 per Zileuton ER 600 mg tablet, down 23% from $2.67 on October 8, 2025. The chart's scale runs from the lowest to the highest price shown, not from zero. NADAC is what retail pharmacies paid their wholesalers, per unit, in CMS's monthly survey; what a patient pays depends on insurance and the pharmacy.
- Zileuton ER 600 mg tablet (generic)
| Strength and form | Brand or generic | Pharmacy cost | 30 tablets, or one pen or vial | 12-month change |
|---|---|---|---|---|
| Zileuton ER 600 mg tablet | Generic | $2.05 per tablet | $61.48 | -23% |
Source: CMS National Average Drug Acquisition Cost (NADAC) survey, October 7, 2026: what retail pharmacies paid per unit; not a counter price
Has zileuton been recalled?
The FDA's Enforcement Report lists 2 recalls naming zileuton since 2019: 0 Class I (the most serious), 2 Class II, 0 Class III; 0 still ongoing. A recall names products and lots, not every product of the medicine.
| Started | Class | Company | Reason |
|---|---|---|---|
| June 10, 2022 | Class II | Lupin Pharmaceuticals Inc. | Failed Dissolution Specifications: Out of specification test results observed in dissolution testing during long term stability study. |
| May 31, 2019 | Class II | Chiesi USA, Inc. | Failed Dissolution Specifications: Out of specification result for dissolution. |
Source: FDA Enforcement Report (drug recalls) via openFDA, through October 8, 2026
What does the zileuton label say about other medicines?
The zileuton label names 8 other medicines in its interaction, contraindication or warning sections. The labels of 9 other medicines name zileuton. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Digoxin | drug interactions | Drug-drug interaction studies in healthy subjects have been conducted with zileuton immediate-release tablets and digoxin, phenytoin, sulfasalazine, and naproxen. |
| Naproxen | drug interactions | Drug-drug interaction studies in healthy subjects have been conducted with zileuton immediate-release tablets and digoxin, phenytoin, sulfasalazine, and naproxen. |
| Phenytoin | drug interactions | Drug-drug interaction studies in healthy subjects have been conducted with zileuton immediate-release tablets and digoxin, phenytoin, sulfasalazine, and naproxen. |
| Prednisone | drug interactions | Other Concomitant Drug Therapy Drug-drug interaction studies conducted in healthy subjects between zileuton immediate-release tablets and prednisone and ethinyl estradiol (oral contraceptive), drugs known to be metabolized by the CYP3A4 isoenzyme, have shown no significant interaction. |
| Propranolol | drug interactions | Coadministration of zileuton immediate-release tablets and propranolol results in a significant increase in propranolol concentrations. |
| Sulfasalazine | drug interactions | Drug-drug interaction studies in healthy subjects have been conducted with zileuton immediate-release tablets and digoxin, phenytoin, sulfasalazine, and naproxen. |
| Theophylline | drug interactions | Reduce theophylline dose and monitor levels. (7.1) Zileuton increases warfarin levels. |
| Warfarin | drug interactions | Monitor prothrombin time and adjust warfarin dose accordingly. (7.2) Zileuton increases propranolol levels and beta-blocker activity. Monitor appropriately. |
Other labels that name zileuton
Source: FDA drug label (Zileuton), 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 for zileuton?
The FDA Adverse Event Reporting System holds 641 reports that list zileuton among the medicines taken, through July 30, 2026, 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.
Reports received each year
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What else is labeled for the same conditions as zileuton?
9 other medicines are given the same way (oral) and in the same FDA class as zileuton or labeled mainly for the same use (asthma), the same class first. Asthma lists all 37 medicines labeled for it, by any route. The first 8 are below. They are listed as records, not as substitutes: whether one can replace another is a prescriber's decision.
| Medicine | Shared indication | Generic labelers (oral) | Pharmacy cost | Shortage |
|---|---|---|---|---|
| Dexamethasone | Asthma | 41 labelers | $0.193 per tablet 4 mg tablet | In shortage |
| Montelukast | Asthma | 36 labelers | $0.0419 per tablet 10 mg tablet | A presentation being discontinued |
| Theophylline | Asthma | 26 labelers | $0.330 per tablet 300 mg tablet | No current entry |
| Albuterol | Asthma | 14 labelers | $0.288 per tablet 2 mg tablet | Resolved |
| Budesonide | Asthma | 14 labelers | $0.498 per capsule 3 mg capsule | No current entry |
| Zafirlukast | Asthma | 5 labelers | $0.623 per tablet 20 mg tablet | No current entry |
| Ephedrine | Asthma | none listed | n/a | No current entry |
| Cromolyn | Asthma | 3 labelers | $0.349 per mL 100 mg/5 mL oral conc | Listed; available |
Source: FDA drug labels (indications), NDC Directory, NADAC of October 7, 2026, FDA shortages (October 8, 2026)
What next?
- Alternatives to zileuton
- 9 medicines for the same use
- Zileuton side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other