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Zileuton

Zileuton is a leukotriene synthesis inhibitor used for the long-term prevention and treatment of asthma in adults and children 12 and older.

Brand names ZyfloZyflo CR
Drug class 5-lipoxygenase Inhibitor
Rx Forms 2
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026 Content updated Oct 2, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 6 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

✓No current FDA shortage listed · checked Oct 6, 2026
Zileuton at a glance The quick version — the full detail is in the Patient Information Guide below.
Dr. Brian Staiger, PharmD, BCPS
The Pharmacist’s Take By · Clinical pharmacist · Written

Zileuton is a daily asthma controller for ages 12 and up that blocks the enzyme 5-lipoxygenase, so the body makes fewer leukotrienes, the chemicals that inflame and tighten airways; on the market since about 1996 and available generically, it is a less common add-on, usually tried after inhaled steroids. Most people tolerate it fairly well, and what they notice is usually upset stomach, nausea or sinus irritation. The real watch-out is the liver, so expect regular liver blood tests (ALT), and stop it and call your prescriber for yellowing skin or eyes, right-sided belly pain or unusual tiredness. It will not stop an attack already underway, so keep your rescue inhaler close.

Clinical pearls

  • Zileuton can roughly double theophylline and propranolol levels and raises warfarin levels, so those prescribers need to know.
  • Take the extended-release tablets within an hour after your morning and evening meals, and never chew, cut or crush them.
  • Report new mood swings, behavior changes or sleep problems, which have been linked to zileuton in both adults and teenagers.
  • Heavy drinking adds to the liver risk, and women 65 and older are more prone to raised liver enzymes.
How we write & review this content — our editorial policy →
How you get itPrescription only
Comes asExtended-release tablet, Tablet
Earliest FDA record1996
Companies listing it with the FDA6
FDA label last updatedNov 30, 2025
FDA’s strongest warning (boxed)None on the label

Patient information guide A plain-language walkthrough of Zileuton, written from its FDA label.

What Zileuton is used for

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Zileuton is approved as a maintenance (long-term control) medicine for asthma. Both available forms cover the same core indication, but the extended-release tablet has an additional explicit instruction: it must not be used during an acute attack.

  • Zyflo tablets are indicated for the prevention and long-term treatment of asthma in adults and children 12 years of age and older.
  • Zileuton extended-release tablets are indicated for the prevention and long-term treatment of asthma in adults and children 12 years of age and older.
  • Zileuton extended-release tablets are not indicated for reversing bronchospasm (airway tightening) during an acute asthma attack — a rescue inhaler is needed for that.
  • Both Zyflo and zileuton extended-release tablets can be continued during an asthma flare-up alongside other treatments.

How Zileuton works

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Zileuton blocks an enzyme called 5-lipoxygenase, which is needed to produce chemicals called leukotrienes. Leukotrienes cause the airways to become inflamed, swollen, and filled with mucus, and they trigger the muscles around the airways to tighten — all hallmarks of asthma. By cutting off leukotriene production, zileuton reduces airway inflammation and helps keep breathing passages more open over time.

The drug is active as both of its molecular forms (called enantiomers), and it reduces measurable leukotriene levels in blood, urine, and airway fluid. This effect on leukotrienes is directly related to zileuton's level in the bloodstream.

Zileuton dosage

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Both forms of zileuton are taken by mouth. The total daily amount is the same for both, but the timing and rules differ by product.

  • Zyflo (tablet): taken four times a day; may be taken with meals and at bedtime for convenience.
  • Zileuton extended-release tablets: taken twice a day, within one hour after your morning and evening meals — food is important for proper absorption. Tablets must not be chewed, cut, or crushed.
  • If you miss a dose of zileuton extended-release tablets, take your next dose at the regular time — never double up.
  • Liver blood tests are required before starting either form and at regular intervals during treatment.

Dosing details from the FDA-approved label

From the Zileuton prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.

  • Symptomatic treatment of patients with asthma (ZYFLO immediate-release tablet)
    • One 600-mg tablet four times a day for a total daily dose of 2400 mg
    • For ease of administration, may be taken with meals and at bedtime. Evaluate hepatic transaminases prior to initiation and periodically during treatment.
  • Asthma in adults and children 12 years of age and older (zileuton extended-release tablets)
    • Two 600 mg extended-release tablets twice daily, within one hour after morning and evening meals, for a total daily dose of 2400 mg
    • Tablets should not be chewed, cut or crushed. If a dose is missed, take the next dose at the scheduled time and do not double the dose. Assess hepatic function enzymes prior to initiation and periodically during treatment.
Read the label’s full dosing text

2 DOSAGE AND ADMINISTRATION The recommended dosage of zileuton extended-release tablets for the treatment of patients with asthma is two 600 mg extended-release tablets twice daily, within one hour after morning and evening meals, for a total daily dose of 2400 mg. Tablets should not be chewed, cut or crushed. If a dose is missed, the patient should take the next dose at the scheduled time and not double the dose. Assess hepatic function enzymes prior to initiation of zileuton extended-release tablets and periodically during treatment [see Contraindications ( 4 ), Warnings and Precautions ( 5 ), and Use in Specific Populations ( 8.7 ) ]. Adults and children 12 years of age and older: The recommended dose of zileuton extended-release tablets is two 600 mg extended-release tablets twice daily, within one hour after morning and evening meals, for a total daily dose of 2400 mg. ( 2 ) Monitoring: Assess hepatic function enzymes prior to initiation of zileuton extended-release tablet and monitor periodically during treatment. ( 2 , 5.1 )

Read the full Dosage and Administration section on DailyMed →

Zileuton side effects

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The most common side effects reported with zileuton extended-release tablets (occurring in 5% or more of patients) were sinusitis, nausea, and throat or voice box pain. Less common but reported reactions include:

Common side effects

  • Sinusitis (sinus infection or inflammation)
  • Nausea
  • Throat or voice box pain (pharyngolaryngeal pain)
  • Upper abdominal pain
  • Diarrhea
  • Upset stomach or indigestion
  • Vomiting
  • Rash
  • Elevated liver enzymes (detected on blood tests)

When to get medical help

  • Signs of liver problems: right-sided upper belly pain, nausea, unusual tiredness, itching, yellowing of the skin or eyes (jaundice), or flu-like symptoms — stop taking zileuton and call your doctor right away
  • Mood or behavior changes, sleep problems, or other unusual mental health symptoms — contact your prescriber promptly
  • Any allergic reaction such as rash or swelling — seek medical help

More serious reactions that require prompt medical attention include signs of liver injury (right-sided belly pain, jaundice, extreme fatigue, itching, or flu-like symptoms) and any new mood changes, behavioral changes, or sleep disturbances.

Zileuton warnings and precautions

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  • Liver injury (hepatotoxicity): Zileuton can raise liver enzymes and, in some cases, cause significant liver damage. Required monitoring includes a liver blood test (ALT) before starting, monthly for the first 3 months, every 2–3 months for the rest of the first year, and periodically after that. Stop taking zileuton and contact your doctor immediately if you develop right-sided belly pain, unusual fatigue, nausea, itching, yellowing of the skin or eyes, or flu-like symptoms. People who drink heavily or have a history of liver disease should use zileuton with extra caution.
  • Neuropsychiatric events: Sleep problems and behavioral or mood changes have been reported in adults and adolescents taking zileuton. If you or someone you care for notices unusual mental or behavioral changes, inform the prescriber promptly. The prescriber will weigh the risks and benefits of continuing treatment.
  • Not for acute attacks: Zileuton extended-release tablets will not stop a sudden asthma attack and should never replace a rescue bronchodilator in that situation.

Zileuton interactions

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Zileuton affects the way certain other medicines are processed by the body, which can raise their levels to potentially dangerous amounts. Key interactions include:

  • Theophylline: Zileuton can roughly double theophylline blood levels, increasing the risk of theophylline toxicity. The theophylline dose typically needs to be cut in half and levels monitored closely.
  • Warfarin (blood thinner): Zileuton raises warfarin levels, which can increase bleeding risk. Clotting tests (prothrombin time) must be checked regularly and warfarin doses adjusted accordingly.
  • Propranolol (beta-blocker): Zileuton can more than double propranolol levels, intensifying its effects on heart rate and blood pressure. The propranolol dose may need to be reduced, and close monitoring is needed.
  • Other beta-blockers: No formal studies exist, but caution and monitoring are recommended when any beta-blocker is combined with zileuton.
  • Alcohol: Heavy alcohol use increases the risk of liver injury with zileuton — limit or avoid alcohol while taking this medicine.

Interactions listed in the FDA-approved label

From the Zileuton prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.

  • Theophylline: Zileuton increases theophylline levels; co-administration with zileuton immediate-release tablets resulted in an approximately 50% decrease in steady-state clearance of theophylline, an approximate doubling of theophylline AUC, a 73% increase in Cmax, and a 24% increase in elimination half-life, with theophylline-related adverse reactions observed more frequ Upon initiation of zileuton in patients receiving theophylline, reduce the theophylline dosage by approximately one-half and monitor plasma theophylline concentrations. When starting theophylline in a patient receiving zileuton, adjust the maintenance dose and/or dosing interval guided by serum theophylline determinations.
  • Warfarin: Zileuton increases warfarin levels; a 15% decrease in R-warfarin clearance and a 22% increase in AUC were accompanied by a clinically significant increase in prothrombin times. S-warfarin pharmacokinetics were not affected. Monitor prothrombin time or other suitable coagulation tests with appropriate dose titration of warfarin.
  • Propranolol: Zileuton significantly increases propranolol concentrations (42% decrease in clearance; increases in Cmax, AUC and elimination half-life of 52%, 104% and 25%) and increases beta-blockade, shown by a decrease in heart rate. Closely monitor patients and reduce the propranolol dose as necessary.
  • Other beta-adrenergic blocking agents (beta-blockers): No formal drug-drug interaction studies between zileuton and other beta-blockers have been conducted. It is reasonable to employ appropriate clinical monitoring when co-administered.
  • CYP3A4 inhibitors, such as ketaconazole: No formal drug-drug interaction studies between zileuton and CYP3A4 inhibitors have been conducted. It is reasonable to employ appropriate clinical monitoring when co-administered.
  • Prednisone and ethinyl estradiol (oral contraceptive): Studies in healthy subjects with zileuton immediate-release tablets showed no significant interaction.
  • Digoxin, phenytoin, sulfasalazine, and naproxen: Studies in healthy subjects with zileuton immediate-release tablets showed no significant interaction with any of these drugs.
Read the label’s full interactions text

7 DRUG INTERACTIONS The following study results were obtained using zileuton immediate-release tablets but the conclusions also apply to Zileuton Extended-Release Tablets. Zileuton increases theophylline levels. Reduce theophylline dose and monitor levels. ( 7.1 ) Zileuton increases warfarin levels. Monitor prothrombin time and adjust warfarin dose accordingly. ( 7.2 ) Zileuton increases propranolol levels and beta-blocker activity. Monitor appropriately. ( 7.3 ) 7.1 Theophylline In a drug-interaction study in 16 healthy subjects, co-administration of multiple doses of zileuton immediate-release tablets (800 mg every 12 hours) and theophylline (200 mg every 6 hours) for 5 days resulted in a significant decrease (approximately 50%) in steady-state clearance of theophylline, an approximate doubling of theophylline AUC, and an increase in theophylline C max (by 73%). The elimination half-life of theophylline was increased by 24%. Also, during co-administration, theophylline-related adverse reactions were observed more frequently than after theophylline alone. Upon initiation of Zileuton Extended-Release Tablets in patients receiving theophylline, the theophylline dosage should be reduced by approximately one-half and plasma theophylline concentrations monitored. Similarly, when initiating therapy with theophylline in a patient receiving Zileuton Extended-Release Tablets, the maintenance dose and/or dosing interval of theophylline should be adjusted accordingly and guided by serum theophylline determinations. 7.2 Warfarin Concomitant administration of multiple doses of zileuton immediate-release tablets (600 mg every 6 hours) and warfarin (fixed daily dose obtained by titration in each subject) to 30 healthy male subjects resulted in a 15% decrease in R-warfarin clearance and an increase in AUC of 22%. The pharmacokinetics of S-warfarin were not affected. These pharmacokinetic changes were accompanied by a clinically significant increase in prothrombin times.

Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →

Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.

🌿213 supplements and herbs with documented Zileuton interactions, ranked by severity Check Zileuton against a supplement or herb →

Before taking Zileuton

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  • Do not take zileuton if you have active liver disease or liver enzyme levels that are persistently 3 times or more the upper limit of normal.
  • Do not take zileuton if you have had an allergic reaction to zileuton or any ingredient in the product.
  • Tell your doctor if you drink alcohol heavily or have any history of liver problems — you may need extra monitoring or this medicine may not be right for you.
  • Not approved for children under 12 years of age; FDA has not required pediatric studies in younger children due to the risk of liver toxicity.
  • Older women (65 and older) may be at increased risk of elevated liver enzymes — inform your prescriber of your age and sex.
  • No dose adjustment is needed for kidney disease or for patients on dialysis.
  • There are no adequate human studies in pregnancy; animal studies showed fetal harm at high doses. Discuss the risks and benefits with your doctor if you are pregnant or planning to become pregnant. A pregnancy registry is available (MothersToBaby, 1-877-311-8972).
  • Zileuton and its metabolites pass into rat milk; it is unknown whether it passes into human breast milk. Discuss breastfeeding with your doctor before taking this medicine.

Zileuton overdose

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Overdose experience with zileuton in humans is limited. In one reported case, a large amount was taken at once and the person recovered after vomiting was induced — with no lasting effects. Zileuton is not removed by dialysis. If an overdose is suspected, contact a Poison Control Center (1-800-222-1222) or seek emergency care right away; treatment is supportive and symptom-based.

What Zileuton does in the body

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Zileuton measurably reduces leukotriene levels in the blood, and this reduction tracks closely with how much zileuton is in the bloodstream. In people with asthma, the drug inhibits leukotriene production in a dose-dependent way, with near-complete suppression achievable at adequate blood levels. It also reduces urinary levels of a specific leukotriene (LTE4), confirming that it cuts off leukotriene synthesis throughout the body, not just locally in the lungs.

How your body processes Zileuton

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Zileuton is well absorbed when taken by mouth, and food meaningfully increases absorption of the extended-release tablets — which is why they should be taken with meals. The drug is about 93% bound to proteins in the blood and is broken down mainly by the liver using enzymes CYP1A2, CYP2C9, and CYP3A4, with a half-life of about 3.2 hours. It is eliminated mainly through the urine (as metabolites), and kidney disease — including dialysis — does not require a dose adjustment. The extended-release form, at steady state with food, reaches similar overall drug exposure to the immediate-release form but with a lower peak concentration.

How to store Zileuton

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Store tablets at controlled room temperature between 20˚-25˚C, (68˚-77˚F). Protect from light.

Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →

213

Supplements & herbs that interact with Zileuton

213 supplements and herbal products have documented interactions with Zileuton in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.

Severity mix
  • Major · 6
  • Moderate · 163
  • Minor · 44
ACTIVATED CHARCOAL Major BEER Major GRAPEFRUIT Major SIBERIAN COCKLEBUR Major ST. JOHN'S WORT Major WINE Major ACACIA RIGIDULA Moderate ADRAFINIL Moderate +205 more
Every supplement checked against Zileuton — ranked by severity The full interaction hub: 6 major · 163 moderate · 44 minor · every one linked to its full report. Check Zileuton against your exact supplements

Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.

Zileuton: pharmacist answers to common questions

Quick, plain-English answers to the questions patients ask most about Zileuton — the kind of thing our pharmacy team would talk through with you at the counter.

Can I use zileuton to stop an asthma attack that's already happening?

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No — zileuton is a controller medicine, not a rescue medicine. It works slowly over time to reduce airway inflammation and prevent attacks, but it won't open your airways quickly during a sudden attack. Always keep your rescue inhaler on hand for those moments, and keep taking zileuton as scheduled even during a flare-up.

Why do I need blood tests while taking zileuton?

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Zileuton can raise liver enzyme levels, and in some people this can lead to real liver injury. Regular blood tests — especially a liver enzyme called ALT — let your doctor catch any problem early. You'll need a test before you start, then monthly for the first three months, then every 2–3 months for the rest of the first year, and periodically after that. It sounds like a lot, but it's a straightforward safety check.

What should I watch for that would make me call my doctor right away?

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The main ones to act on fast are signs of liver trouble — right-sided belly pain, unusual tiredness, nausea, itching, or yellowing of your skin or the whites of your eyes. Also call your prescriber if you notice mood changes, new sleep problems, or behavioral changes you can't explain. These are less common but serious enough to report promptly.

I take warfarin and my doctor just added zileuton. Should I be worried?

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Your doctor is right to keep a close eye on this combination. Zileuton raises warfarin levels in the blood, which can increase your risk of bleeding. You'll need more frequent blood clotting tests (called prothrombin time or INR) and your warfarin dose may need to be adjusted. It's manageable — just make sure all your doctors and your pharmacist know you're on both medications.

Does it matter if I take the extended-release tablets with food or on an empty stomach?

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Yes, it really does matter for the extended-release form. Food significantly increases how much of the drug your body absorbs. Take zileuton extended-release tablets within one hour after your morning and evening meals — and don't chew, cut, or crush them. Swallow them whole so the extended-release mechanism works correctly.

Is zileuton safe to take during pregnancy?

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There isn't enough human data to say for certain. Animal studies did show some fetal harm at high doses, so this is a real conversation to have with your doctor. They can weigh the risks of untreated asthma against the potential risks of the medicine and help you decide what's best. If you become pregnant while taking zileuton, let your prescriber know right away. There is also a free pregnancy registry you can join — MothersToBaby at 1-877-311-8972.

Is Zileuton available over the counter?

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No. Zileuton is a prescription medicine: every Zileuton product listed with the FDA is prescription only, so it is not sold over the counter. Your prescriber decides whether it is appropriate for you, and your pharmacist dispenses it.

When was Zileuton first available?

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The earliest FDA record we hold for Zileuton is from 1996: its first approval in Drugs@FDA or its earliest product listing in the NDC Directory, whichever is older. Many older medicines were in use before their first formal FDA approval, so this is the earliest date on record, not necessarily when Zileuton was first used.

Who makes Zileuton?

▾
6 companies currently list Zileuton products in the FDA's NDC Directory, including Camber Pharmaceuticals, Inc., Chiesi USA, Inc., Golden State Medical Supply, Inc.. That count includes repackagers and distributors as well as manufacturers (companies that sell only the raw ingredient are not counted), so fewer companies actually make it; the label on your bottle names the one that supplied yours.

Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →

More about Zileuton on HelloPharmacist

📊Zileuton supplement interactions213 checked — ranked by severity 🌿Drug & Supplement CheckerZileuton vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Zileuton NDCs & costs 🅰️Browse Drugs A–ZLook up any medication
Detailed data & references for Zileuton Forms & strengths, pricing, billing codes, manufacturers, safety reports and sourcing — the data behind the page. Most people can stop here. Each section below opens on a tap.

Zileuton forms and strengths (how it comes)

Zileuton is available in 2 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Zileuton inactive ingredients by manufacturer.

Extended-release tablet

By mouth
How this form is used
What it may be used for
  • Zileuton extended-release tablets are used for the prevention and long-term treatment of asthma in adults and children 12 years of age and older.
  • Zileuton extended-release tablets are not for reversing a sudden asthma attack — do not use them in place of a rescue inhaler.
  • Zileuton extended-release tablets can be continued during an asthma flare-up.
Important instructions
  • Zileuton extended-release tablets are taken twice a day — within one hour after morning and evening meals.
  • Do not chew, cut, or crush the extended-release tablets; swallow them whole.
  • If a dose is missed, take the next dose at the scheduled time — do not take a double dose.
  • Liver enzyme blood tests must be checked before starting and monitored regularly during treatment.
Available strengths 1 strength
600 mg
7 FDA-listed product records ⓘ

Tablet

By mouth
Brands Zyflo
How this form is used
What it may be used for
  • Zyflo is used for the prevention and long-term treatment of asthma in adults and children 12 years of age and older.
  • Zyflo is not for stopping a sudden asthma attack — use your rescue inhaler for that.
  • Zyflo can be continued during an asthma flare-up.
Important instructions
  • Zyflo tablets are taken four times a day.
  • Zyflo may be taken with meals and at bedtime for convenience.
  • Liver enzyme blood tests should be checked before starting Zyflo and periodically during treatment.
  • Follow your prescriber's instructions for how long to continue Zyflo.
Available strengths 1 strength
600 mg
2 FDA-listed product records ⓘ

Zileuton on the U.S. market: products, makers and brands

How Zileuton appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

6 companies list 6 Zileuton product records with the FDA, mostly as extended-release tablet, tablet; the earliest marketing or approval year on record is 1996. Brand names on the directory include Zyflo, Zyflo CR; the rest are generics.

2
Dose forms ⓘ
6
Labelers (makers, repackagers, distributors)
2
Brand names
6
FDA-listed product records ⓘ
1996
Earliest FDA record ⓘ

FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

Also listed with the FDA, not a patient dose form: Powder (8) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.

Camber Pharmaceuticals, Inc.17%
Chiesi USA, Inc.17%
Golden State Medical Supply, Inc.17%
NorthStar RxLLC17%
Rising Pharma Holdings, Inc.17%
Strides Pharma Science Limited17%

Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

How widely Zileuton is used (Medicaid data)

A general measure of how commonly Zileuton is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.

Think of this as a proxy for how widely Zileuton is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.

5,278
Medicaid prescriptions filled (Q1–Q4 2025)
$2.5M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Zileuton prescribed? Of the 1,601 medications we measure, Zileuton ranks #1,037 by Medicaid prescriptions — more than 35% of them.

Where Zileuton ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #1,037 of 1,601
#1,032 Ceftazidime Injection 5,585 Rx #1,033 Methylergonovine 5,549 Rx #1,034 Dalbavancin Injection 5,497 Rx #1,035 Rivastigmine Transderm... 5,404 Rx #1,036 Levofloxacin Injection 5,358 Rx #1,037 Zileuton 5,278 Rx #1,038 Lamivudine 5,277 Rx #1,039 Ozanimod 5,236 Rx #1,040 Orlistat 5,217 Rx #1,041 Pimozide 5,148 Rx #1,042 Desipramine 5,105 Rx

Utilization by Zileuton product

Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.

12 HR zileuton 600 MG Extended Release Oral Tablet

5,278 Medicaid prescriptions (Q1–Q4 2025) 100% of Zileuton prescriptions shown $2.5M gross reimbursement (before rebates) ≈ $472 per prescription (gross)

Summed across the 4 of 9 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 730834

Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.

Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Zileuton, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 4 of 9 listed Zileuton NDCs with Medicaid activity.

Compare Zileuton products

A representative set of FDA-listed product records for Zileuton — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)

Strength Route Manufacturer / Labeler Category ⓘ Details
💊Extended-release tablet
600 mg Oral Camber Pharmaceuticals, Inc. ANDA View NDC →
600 mg Oral Golden State Medical Supply, Inc. ANDA View NDC →
600 mg Oral NorthStar RxLLC ANDA View NDC →
600 mg Oral Rising Pharma Holdings, Inc. ANDA View NDC →
600 mg Oral Strides Pharma Science Limited ANDA View NDC →
💊Tablet
600 mg Oral Chiesi USA, Inc. NDA View NDC →

Showing 6 of 6 products — FDA National Drug Code Directory. See every product, package size and price: browse all 6 Zileuton NDCs →

Zileuton recall history

A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.

The FDA’s enforcement reports list no Zileuton recalls since July 2021.

✅No Zileuton recalls on record since July 2021

Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Zileuton RxCUI 40575 2 dose forms · 2 strengths
  1. Dose form (SCDF) Extended Release Oral Tablet RxCUI 723847 In current FDA listings
    Clinical drug / strength (SCD) 12 HR zileuton 600 MG RxCUI 730834
  2. Dose form (SCDF) Oral Tablet RxCUI 374334 In current FDA listings
    Clinical drug / strength (SCD) 600 MG RxCUI 199904

Look up RxCUI 40575 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

💵 What Zileuton costs pharmacies (NADAC benchmark)

The national average invoice price pharmacies pay for the drug itself, from CMS's NADAC survey (data as of Sep 30, 2026). This is a supply-cost benchmark — not a retail price and not what you'd pay at the counter.

FormStrengthPharmacy acquisition benchmark
Tablet, Extended Release · Oral 600 mg $2.05 per tablet NDC details & price history
Tablet, Film Coated, Extended Release · Oral 600 mg $2.05 per tablet NDC details & price history
Why show this? Your out-of-pocket cost depends on insurance, pharmacy markup, and discounts — but the acquisition benchmark tells you whether the medication itself is inexpensive or costly, which strengths cost more per dose, and whether a cash-price quote is in a reasonable range. Each row links to the NDC-level record with its full price history.

Source: CMS National Average Drug Acquisition Cost (NADAC), a survey of retail pharmacy invoice prices. Benchmarks shown are the range across package sizes of a representative product for each form and strength — other manufacturers' products may differ.

Zileuton brand names

Zileuton is sold under 2 brand names in the FDA directory — Zyflo, Zyflo CR. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.

Zyflo Zyflo CR

Who makes Zileuton: manufacturers and labelers

6 companies list Zileuton products with the FDA. By number of product records, the largest are Camber Pharmaceuticals, Inc., Chiesi USA, Inc., Golden State Medical Supply, Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.

Camber Pharmaceuticals, Inc. 1 Chiesi USA, Inc. 1 Golden State Medical Supply, Inc. 1 NorthStar RxLLC 1 Rising Pharma Holdings, Inc. 1 Strides Pharma Science Limited 1

Zileuton drug class (RxNorm)

Zileuton belongs to the 5-Lipoxygenase Inhibitor class.

Pharmacologic class 5-Lipoxygenase Inhibitor
How it works 5-Lipoxygenase Inhibitors

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

Sources for this Zileuton page

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Nov 30, 2025
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Zileuton.
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Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
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Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Zileuton after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
6
Finished products in the current FDA directory
6
Companies listing them (makers, repackagers, distributors)
6
FDA labeler codes behind them ⓘ
6
Linked representative label ⓘ
Chiesi USA, Inc.
Linked label effective
Nov 30, 2025
Composite sections available
22
Linked SPL Set ID
aee65202-fddb-497f-9f11-17cc727cb157
Linked SPL Document ID
d49e40c7-0635-4220-8b0a-c5068116ee17
Open the linked representative label on DailyMed ↗
NDC package records associated with this linked SPL 1

How this page is built

HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Chiesi USA, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →