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Isoniazid

Isoniazid is an antibiotic used to treat tuberculosis (TB) caused by susceptible bacteria and to help prevent TB infection from turning into active disease in people at higher risk.

Brand names HyzydInhLaniazidNydrazidRimifon +2 more
Drug class Antimycobacterial
Rx Forms 3
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 27 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 8, 2026
Isoniazid 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

Isoniazid is a first-choice tuberculosis antibiotic that stops TB bacteria from building their cell wall. It has been on the U.S. market since about 1972 and is available as a generic, combined with other TB drugs for active disease and used alone to keep a latent (sleeping) infection from turning active. Many people tolerate it well, though some notice an upset stomach or tingling in the hands and feet. The real concern is its boxed warning for severe, sometimes fatal hepatitis (liver inflammation), so skip alcohol, keep your monthly checkups, and report dark urine, yellow eyes, nausea or loss of appetite promptly.

Clinical pearls

  • Take it on an empty stomach, and skip aged cheese, red wine, tuna and skipjack, which can trigger flushing, headache or sweating.
  • Many prescribers add vitamin B6 (pyridoxine) to help prevent the nerve tingling, especially with diabetes, alcohol use or poor nutrition.
  • Use acetaminophen (Tylenol) sparingly, if at all, because severe toxicity has been reported alongside isoniazid.
  • Isoniazid can raise blood levels of phenytoin, carbamazepine, valproate and theophylline, so those levels may need closer checks.
How we write & review this content — our editorial policy →
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾

Isoniazid can cause severe, sometimes fatal liver inflammation (hepatitis). It can happen even after many months of treatment, though it most often appears in the first three months.

The risk goes up with age, daily alcohol use, chronic liver disease and injection drug use. It may also be higher in women, especially Black and Hispanic women, and after childbirth. You should be checked monthly for symptoms. People 35 and older should have liver blood tests before starting and periodically during treatment.

Report these signs right away: unexplained loss of appetite, nausea, vomiting, dark urine, yellow skin or eyes, rash, ongoing tingling in the hands or feet, persistent tiredness or weakness, fever lasting more than 3 days, or belly pain, especially in the upper right side. Continuing the drug after liver damage starts can make it worse.

Read the full warning on DailyMed →
How you get itPrescription only
Comes asTablet, Oral solution, Injection
Earliest FDA record1952
Companies listing it with the FDA14
FDA label last updatedNov 1, 2019
FDA’s strongest warning (boxed)Yes, read the warning

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

What Isoniazid is used for

▾

Isoniazid is used to treat and help prevent tuberculosis (TB).

  • Treatment of all forms of TB caused by susceptible organisms, always with other TB medicines (tablets, oral solution and injection).
  • Preventive therapy for people with HIV infection or suspected HIV infection.
  • Preventive therapy for close contacts of someone with newly diagnosed infectious TB.
  • Preventive therapy for recent skin-test converters and for people with old healed TB on chest X-ray.
  • Preventive therapy for people with conditions that raise TB risk, such as diabetes, silicosis, end-stage renal disease, long-term steroid or immunosuppressive therapy, and poor nutrition.
  • Preventive therapy for certain people under 35 in high-incidence groups, and for children under 4 with a positive skin test.
  • Isoniazid Injection is given by intramuscular injection when the oral route is not possible.

How Isoniazid works

▾

Isoniazid stops TB bacteria from making mycolic acids, an essential part of their cell wall. At therapeutic levels it kills actively growing TB bacteria inside and outside cells.

TB can become resistant through gene mutations, and this develops quickly if isoniazid is used alone. That is why it is combined with other medicines for active TB.

Isoniazid dosage

▾

Isoniazid comes as tablets, an oral solution and an intramuscular injection. It is usually taken once daily or two to three times weekly, depending on the regimen. Take it without food, since food lowers absorption.

  • For active TB it is used with other TB medicines.
  • Twice- or three-times-weekly regimens should be given by directly observed therapy.
  • Your prescriber chooses the dose and length of treatment. Follow your label.

Dosing details from the FDA-approved label

From the Isoniazid 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.

  • Treatment of tuberculosis - Adults
    • 5 mg/kg up to 300 mg daily in a single dose
    • Or 15 mg/kg up to 900 mg/day, two or three times/week
    • Maximum: 300 mg daily; 900 mg/day for two or three times/week dosing
    • Used in conjunction with other effective anti-tuberculous agents; twice or 3 times weekly regimens by directly observed therapy
  • Treatment of tuberculosis - Children
    • 10 mg/kg to 15 mg/kg up to 300 mg daily in a single dose
    • Or 20 mg/kg to 40 mg/kg up to 900 mg/day, two or three times/week
    • Maximum: 300 mg daily; 900 mg/day for two or three times/week dosing
    • Ethambutol not suggested in children whose visual acuity cannot be monitored
  • Pulmonary tuberculosis without HIV infection (children and adults) - Option 1
    • Daily isoniazid, rifampin and pyrazinamide for 8 weeks followed by 16 weeks of isoniazid and rifampin daily or 2 to 3 times weekly
    • Add ethambutol or streptomycin until sensitivity to isoniazid and rifampin is demonstrated
  • Pulmonary tuberculosis without HIV infection (children and adults) - Option 2
    • Daily isoniazid, rifampin, pyrazinamide and streptomycin or ethambutol for 2 weeks followed by twice weekly administration of the same drugs for 6 weeks, subsequently twice weekly isoniazid and rifampin for 16 weeks
  • Pulmonary tuberculosis without HIV infection (children and adults) - Option 3
    • Three times weekly with isoniazid, rifampin, pyrazinamide and ethambutol or streptomycin for 6 months
    • Directly observed therapy
  • Extra pulmonary tuberculosis
    • 6 to 9 month short-course regimen
    • Miliary, bone/joint tuberculosis and tuberculous meningitis in infants and children should receive 12 month therapy
  • Pregnant women with tuberculosis
    • Initial regimen of isoniazid and rifampin
    • Ethambutol should be included unless primary isoniazid resistance is unlikely
    • Streptomycin and routine pyrazinamide not recommended in pregnancy
  • Preventive therapy of tuberculosis - Adults over 30 kg
    • 300 mg per day in a single dose
    • Exclude bacteriologically positive or radiographically progressive tuberculosis before starting
  • Preventive therapy of tuberculosis - Infants and children
    • 10 mg/kg (up to 300 mg daily) in a single dose
    • Maximum: 300 mg daily
  • Preventive therapy when daily adherence cannot be assured
    • 20 mg/kg to 30 mg/kg twice weekly under direct observation of a health care worker
    • Maximum: 900 mg
Read the label’s full dosing text

DOSAGE AND ADMINISTRATION (See also INDICATIONS AND USAGE ) NOTE: For preventive therapy of tuberculous infection and treatment of tuberculosis, it is recommended that physicians be familiar with the following publications: (1) the recommendations of the Advisory Council for the Elimination of Tuberculosis, published in the MMWR: vol 42; RR-4, 1993 and (2) Treatment of Tuberculosis and Tuberculosis Infection in Adults and Children, American Journal of Respiratory and Critical Care Medicine: vol 149; 1359-1374, 1994. For Treatment of Tuberculosis Isoniazid is used in conjunction with other effective anti-tuberculous agents. Drug susceptibility testing should be performed on the organisms initially isolated from all patients with newly diagnosed tuberculosis. If the bacilli becomes resistant, therapy must be changed to agents to which the bacilli are susceptible. Usual Oral Dosage (depending on the regimen used): Adults 5 mg/kg up to 300 mg daily in a single dose; or 15 mg/kg up to 900 mg/day, two or three times/week Children 10 mg/kg to 15 mg/kg up to 300 mg daily in a single dose; or 20 mg/kg to 40 mg/kg up to 900 mg/day, two or three times/week Patients with Pulmonary Tuberculosis Without HIV Infection There are 3 regimen options for the initial treatment of tuberculosis in children and adults: Option 1: Daily isoniazid, rifampin, and pyrazinamide for 8 weeks followed by 16 weeks of isoniazid and rifampin daily or 2 to 3 times weekly. Ethambutol or streptomycin should be added to the initial regimen until sensitivity to isoniazid and rifampin is demonstrated. The addition of a fourth drug is optional if the relative prevalence of isoniazid-resistant Mycobacterium tuberculosis isolates in the community is less than or equal to four percent. Option 2: Daily isoniazid, rifampin, pyrazinamide, and streptomycin or ethambutol for 2 weeks followed by twice weekly administration of the same drugs for 6 weeks, subsequently twice weekly isoniazid and rifampin for 16 weeks. Option 3: Three times weekly with isoniazid, rifampin, pyrazinamide and ethambutol or streptomycin for 6 months. * All regimens given twice weekly or 3 times weekly should be administered by directly observed therapy (see also Directly Observed Therapy (DOT)).

Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →

Isoniazid side effects

▾

The most frequent reactions involve the nervous system and the liver.

Common side effects

  • Numbness or tingling in the hands and feet (peripheral neuropathy)
  • Nausea and vomiting
  • Upset stomach (epigastric distress)
  • Mild, temporary rise in liver enzymes
  • Fever or skin rash
  • Loss of appetite, tiredness and weakness

When to get medical help

  • Call your doctor right away for unexplained loss of appetite, nausea or vomiting, dark urine, yellowing of the skin or eyes, or pain in the upper right belly. These can be signs of liver damage.
  • Report persistent tiredness, weakness, or a fever lasting more than 3 days.
  • Report ongoing numbness or tingling in your hands or feet.
  • Stop the medicine and get help right away for a severe skin reaction, such as widespread rash, blistering or peeling skin.
  • Report clumsiness, unsteady walking, tremor, slurred speech or eye movements you cannot control, which may signal cerebellar syndrome (a problem with balance and coordination).
  • Get help for vision changes, seizures, confusion or memory problems.
  • Report easy bruising or bleeding, or signs of blood problems.

Isoniazid warnings and precautions

▾
  • Liver injury: severe and sometimes fatal hepatitis can occur, most often in the first three months. Risk rises with age and alcohol use.
  • Severe skin reactions: TEN, SJS, DRESS and AGEP have been reported. Stop the drug at once if they occur.
  • Cerebellar syndrome: balance and coordination problems, most often reported in people with chronic kidney disease. Stop the drug if it occurs.
  • Nerve damage: peripheral neuropathy is the most common toxic effect, especially in malnourished people, alcohol users and people with diabetes.

Isoniazid interactions

▾

Isoniazid affects several other medicines and some foods.

  • Food: lowers absorption, so take it without food.
  • Cheese, red wine and tuna-type fish: can cause reactions such as headache, flushing or low blood pressure.
  • Alcohol: increases liver injury risk.
  • Acetaminophen: severe toxicity has been reported.
  • Carbamazepine, phenytoin, valproate, theophylline: levels can rise, so monitoring and dose changes may be needed.
  • Ketoconazole: levels may fall when used with isoniazid and rifampin.

Interactions listed in the FDA-approved label

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

  • Food: Bioavailability of isoniazid is reduced significantly when administered with food. Isoniazid should not be administered with food.
  • Tyramine- and histamine-containing foods: Isoniazid has some monoamine oxidase inhibiting activity, so tyramine-containing foods (cheese, red wine) may interact; diamine oxidase may also be inhibited, causing exaggerated response (e.g., headache, sweating, palpitations, flushing, hypotension) to histamine-containing foods (e.g., skipjack, tuna, other tropical fish). Tyramine- and histamine-containing foods should be avoided.
  • Acetaminophen: A report of severe acetaminophen toxicity in a patient receiving isoniazid; isoniazid induces P-450IIE1, which may generate more toxic acetaminophen metabolites.
  • Carbamazepine: Isoniazid slows the metabolism of carbamazepine and increases its serum levels. Determine carbamazepine levels before concurrent administration, monitor closely for signs and symptoms of toxicity, and adjust the anticonvulsant dosage appropriately.
  • Ketoconazole: Potential interaction; when given with isoniazid and rifampin the AUC of ketoconazole is decreased by as much as 88 percent after 5 months of concurrent therapy.
  • Phenytoin: Isoniazid may increase serum levels of phenytoin. Make appropriate adjustment of the anticonvulsant to avoid phenytoin intoxication.
  • Theophylline: Concomitant use may cause elevated plasma levels of theophylline and in some instances a slight decrease in the elimination of isoniazid. Monitor theophylline serum levels closely and adjust theophylline dosage appropriately.
  • Valproate: A possible increase in the plasma level of valproate when co-administered with isoniazid. Monitor plasma valproate concentration and adjust valproate dosage appropriately.
Read the label’s full interactions text

Drug Interactions Food Isoniazid should not be administered with food. Studies have shown that the bioavailability of isoniazid is reduced significantly when administered with food. Tyramine- and histamine-containing foods should be avoided in patients receiving isoniazid. Because isoniazid has some monoamine oxidase inhibiting activity, an interaction with tyramine-containing foods (cheese, red wine) may occur. Diamine oxidase may also be inhibited, causing exaggerated response (e.g., headache, sweating, palpitations, flushing, hypotension) to foods containing histamine (e.g., skipjack, tuna, other tropical fish). Acetaminophen A report of severe acetaminophen toxicity was reported in a patient receiving isoniazid. It is believed that the toxicity may have resulted from a previously unrecognized interaction between isoniazid and acetaminophen and a molecular basis for this interaction has been proposed. However, current evidence suggests that isoniazid does induce P-450IIE1, a mixed-function oxidase enzyme that appears to generate the toxic metabolites, in the liver. Furthermore it has been proposed that isoniazid resulted in induction of P-450IIE1 in the patient’s liver which, in turn, resulted in a greater proportion of the ingested acetaminophen being converted to the toxic metabolites. Studies have demonstrated that pretreatment with isoniazid potentiates acetaminophen hepatotoxicity in rats 1,2 . Carbamazepine Isoniazid is known to slow the metabolism of carbamazepine and increase its serum levels. Carbamazepine levels should be determined prior to concurrent administration with isoniazid, signs and symptoms of carbamazepine toxicity should be monitored closely and appropriate dosage adjustment of the anticonvulsant should be made 3 . Ketoconazole Potential interaction of ketoconazole and isoniazid may exist.

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.

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

Before taking Isoniazid

▾
  • Do not use if you have acute liver disease or past isoniazid-related liver injury.
  • Do not use if you had a severe reaction to isoniazid, such as drug fever, chills or arthritis.
  • Tell your doctor about alcohol use, chronic liver disease, injection drug use, diabetes, kidney disease or poor nutrition.
  • People 35 and older need liver tests before and during treatment.
  • Women, particularly Black and Hispanic women, and the post-partum period may need closer monitoring.
  • Isoniazid crosses the placenta and enters breast milk, so discuss pregnancy and breastfeeding with your prescriber.

Isoniazid overdose

▾

Overdose can cause nausea, vomiting, dizziness, slurred speech, blurred vision and hallucinations within 30 minutes to 3 hours. Larger overdoses can cause breathing trouble, coma and severe seizures. This is an emergency: get medical help right away. Treatment includes intravenous pyridoxine (vitamin B6) and supportive care.

What Isoniazid does in the body

▾

Isoniazid blocks mycolic acid synthesis and kills actively growing TB bacteria. High doses can use up vitamin B6 (pyridoxine) in adults. Resistance develops rapidly when it is used alone.

How your body processes Isoniazid

▾

After oral dosing, isoniazid peaks in the blood within 1 to 2 hours and falls to half or less within 6 hours. It spreads into body fluids and tissues, crosses the placenta and enters milk. About 50 to 70 percent is passed in urine within 24 hours.

The body breaks it down mainly by acetylation, which is genetically determined. Slow acetylators have higher blood levels and a greater chance of toxic effects.

How to store Isoniazid

▾

Protect from moisture and light. Dispense in a tight, light-resistant container as defined in the USP, with a child-resistant closure (as required). Store at 20° to 25°C (68° to 77°F) .

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

84

Supplements & herbs that interact with Isoniazid

84 supplements and herbal products have documented interactions with Isoniazid 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 · 4
  • Moderate · 67
  • Minor · 13
ACTIVATED CHARCOAL Major BEER Major SIBERIAN COCKLEBUR Major WINE Major ADRAFINIL Moderate ASHWAGANDHA Moderate BIOFEEDBACK Moderate BLACK COHOSH Moderate +76 more
Every supplement checked against Isoniazid — ranked by severity The full interaction hub: 4 major · 67 moderate · 13 minor · every one linked to its full report. Check Isoniazid 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.

2

Nutrient depletion considerations

Isoniazid has been associated with lower levels of 2 nutrients in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.

NIACIN Moderate Depletion VITAMIN B6 Moderate Depletion
See the full Isoniazid nutrient depletion report

Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.

Isoniazid: pharmacist answers to common questions

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

What is isoniazid for?

▾
It treats tuberculosis (TB) caused by susceptible bacteria and is also used to prevent TB infection from becoming active disease in people at higher risk. For active TB, you will take it with other TB medicines, because isoniazid alone is not enough.

How should I take it?

▾
Take it exactly as your prescriber directs, without food, since food reduces how much your body absorbs. It is usually taken daily or a few times a week. Some schedules are given with a health professional watching, and it is important not to skip doses.

What side effects should I expect?

▾
Some people have nausea, stomach upset, or tingling in the hands and feet. Mild liver enzyme rises are fairly common and are checked with blood tests. Call your doctor if the tingling does not go away.

What warning signs should make me call right away?

▾
Call right away for loss of appetite, nausea or vomiting, dark urine, yellow skin or eyes, belly pain on the upper right, unusual tiredness, or fever lasting more than 3 days. Also call for a bad rash or blistering skin, or trouble with balance or coordination. These can be signs of serious problems.

Can I drink alcohol or take other medicines with it?

▾
Daily alcohol raises your risk of liver injury, so it is best to avoid it. Tell me about any other medicines you use. Acetaminophen, seizure medicines like phenytoin, carbamazepine and valproate, and theophylline can interact. Also avoid aged cheese, red wine and fish like tuna.

Will I need blood tests?

▾
Yes, if you are 35 or older, liver tests are done before you start and periodically during treatment. Everyone should be checked for symptoms monthly. Those at higher risk may need more frequent monitoring.

Is Isoniazid available over the counter?

▾
No. Isoniazid is a prescription medicine: every Isoniazid 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 Isoniazid first available?

▾
The earliest FDA record we hold for Isoniazid is from 1952: 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 Isoniazid was first used.

Who makes Isoniazid?

▾
14 companies currently list Isoniazid products in the FDA's NDC Directory, including Bryant Ranch Prepack, A-S Medication Solutions, Chartwell RX, LLC. 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 Isoniazid on HelloPharmacist

📊Isoniazid supplement interactions84 checked — ranked by severity 🌿Drug & Supplement CheckerIsoniazid vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Isoniazid NDCs & costs 🅰️Browse Drugs A–ZLook up any medication
Detailed data & references for Isoniazid 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.

Isoniazid forms and strengths (how it comes)

Isoniazid is available in 3 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 Isoniazid inactive ingredients by manufacturer.

Tablet

By mouth
How this form is used
What it may be used for
  • Isoniazid tablets are recommended for all forms of tuberculosis caused by susceptible organisms.
  • Isoniazid tablets are also recommended as preventive therapy in the groups listed on its label.
Important instructions
  • Isoniazid tablets are taken by mouth and used with other effective TB medicines for treating active TB.
  • Isoniazid tablets given twice or three times weekly should be given by directly observed therapy.
Available strengths 2 strengths
100 mg 300 mg
33 FDA-listed product records ⓘ

Oral solution

By mouth
How this form is used
What it may be used for
  • Isoniazid oral solution is recommended for all forms of tuberculosis caused by susceptible organisms.
  • Isoniazid oral solution is also recommended as preventive therapy in the groups listed on its label.
Important instructions
  • Isoniazid oral solution is taken by mouth and used with other effective TB medicines for treating active TB.
Available strengths 1 strength
50 mg/5 mL
4 FDA-listed product records ⓘ

Injection

Into a muscle
How this form is used
What it may be used for
  • Isoniazid Injection is recommended for all forms of tuberculosis caused by susceptible organisms.
  • Isoniazid Injection is also recommended as preventive therapy in the groups listed on its label.
Important instructions
  • Isoniazid Injection is given intramuscularly and is intended for use whenever taking it by mouth is not possible.
  • Isoniazid Injection is used together with other effective TB medicines.
Available strengths 1 strength
100 mg/mL
2 FDA-listed product records ⓘ

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

How Isoniazid 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.

14 companies list 27 Isoniazid product records with the FDA, mostly as tablet, oral solution, injection; the earliest marketing or approval year on record is 1952. Brand names on the directory include Hyzyd, Inh, Laniazid and 4 more; the rest are generics.

3
Dose forms ⓘ
14
Labelers (makers, repackagers, distributors)
1
Brand names
27
FDA-listed product records ⓘ
1952
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.

Bryant Ranch Prepack19%
A-S Medication Solutions11%
Chartwell RX, LLC7%
Coupler LLC7%
Genus Lifesciences7%
Marlex Pharmaceuticals, Inc.7%
Other makers41%

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

How widely Isoniazid is used (Medicaid data)

A general measure of how commonly Isoniazid 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 Isoniazid 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.

30,009
Medicaid prescriptions filled (Q1–Q4 2025)
$1.6M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Isoniazid prescribed? Of the 1,601 medications we measure, Isoniazid ranks #739 by Medicaid prescriptions — more than 54% of them.

Where Isoniazid ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #739 of 1,601
#734 Triazolam 30,954 Rx #735 Cobicistat / Darunavir... 30,573 Rx #736 Chlorzoxazone 30,247 Rx #737 Fluorouracil Topical 30,176 Rx #738 Febuxostat 30,153 Rx #739 Isoniazid 30,009 Rx #740 Capecitabine 29,934 Rx #741 Thiamine (Vitamin B<su... 29,550 Rx #742 Empagliflozin / Linagl... 29,523 Rx #743 Rituximab Injection 29,521 Rx #744 Mesalamine Rectal 29,129 Rx

Utilization by Isoniazid 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.

The 300 mg oral tablet is the most-dispensed Isoniazid product — about 96% of these Medicaid prescriptions.

isoniazid 300 MG Oral Tablet Most dispensed

28,673 Medicaid prescriptions (Q1–Q4 2025) 96% of Isoniazid prescriptions shown $1.3M gross reimbursement (before rebates) ≈ $45 per prescription (gross)

Summed across the 9 of 78 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 197832

isoniazid 100 MG Oral Tablet

713 Medicaid prescriptions (Q1–Q4 2025) 2% of Isoniazid prescriptions shown $60,715 gross reimbursement (before rebates) ≈ $85 per prescription (gross)

Summed across the 3 of 15 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 311166

isoniazid 10 MG/ML Oral Solution

623 Medicaid prescriptions (Q1–Q4 2025) 2% of Isoniazid prescriptions shown $243,613 gross reimbursement (before rebates) ≈ $391 per prescription (gross)

Summed across the 1 of 4 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 105292

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 Isoniazid, 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 13 of 97 listed Isoniazid NDCs with Medicaid activity.

Compare Isoniazid products

A representative set of FDA-listed product records for Isoniazid — 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.)

Showing 27 of 27 products — FDA National Drug Code Directory. See every product, package size and price: browse all 27 Isoniazid NDCs →

Isoniazid side effects reported to the FDA (FAERS)

After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Isoniazid — a signal of what to watch for, not proof the drug caused it.

The effects most often named in FDA reports that mention Isoniazid are pyrexia, drug interaction, nausea; about 91% of the reports were classed as serious. These are voluntary reports, so they show what people report, not how often it happens.

16,105
Reports mentioning it
91%
Reported as serious
12
Distinct effects shown
Most reported effects
Pyrexia
1,102
Drug Interaction
935
Nausea
903
Drug-induced Liver Injury
862
Drug Reaction With Eosinophilia And Systemic Symptoms
744
Vomiting
636
Headache
614
Paradoxical Drug Reaction
553
Tuberculosis
547
Arthralgia
546
Age groups
Adult · 2,055Elderly · 647Child · 140Adolescent · 96Infant · 65Neonate · 58

Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Isoniazid in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.

Isoniazid FDA approval history

How Isoniazid went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.

Isoniazid was first approved by the FDA in 1952 (Brand: NYDRAZID · Sandoz); the first generic version was approved in 1970. It remains available in U.S. pharmacies today.

1952
Brand approved
Brand: NYDRAZID · Sandoz
1970
First generic approved
Lower-cost ANDA competition begins
2026
Available today
Active in U.S. pharmacies

Source: Drugs@FDA.

Isoniazid 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 Isoniazid recalls since July 2021.

✅No Isoniazid recalls on record since July 2021

Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Oct 8, 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) Isoniazid RxCUI 6038 3 dose forms · 6 strengths
  1. Dose form (SCDF) Injectable Solution RxCUI 370715 In current FDA listings
    Clinical drug / strength (SCD) 25 MG/ML RxCUI 105293 100 MG/ML RxCUI 204430
  2. Dose form (SCDF) Oral Solution RxCUI 379262 In current FDA listings
    Clinical drug / strength (SCD) 10 MG/ML RxCUI 105292
  3. Dose form (SCDF) Oral Tablet RxCUI 370716 In current FDA listings
    Clinical drug / strength (SCD) 50 MG RxCUI 311171 100 MG RxCUI 311166 300 MG RxCUI 197832

Look up RxCUI 6038 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 Isoniazid 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 · Oral 300 mg $3.40 per tablet NDC details & price history
Tablet · Oral 100 mg $1.73 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.

Isoniazid brand names

Isoniazid is sold under 7 brand names in the FDA directory — Hyzyd, Inh, Laniazid, Nydrazid and others. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.

Hyzyd Inh Laniazid Nydrazid Rimifon Stanozide Tubizid

Who makes Isoniazid: manufacturers and labelers

14 companies list Isoniazid products with the FDA. By number of product records, the largest are Bryant Ranch Prepack, A-S Medication Solutions, Chartwell RX, LLC. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.

Bryant Ranch Prepack 5 A-S Medication Solutions 3 Chartwell RX, LLC 2 Coupler LLC 2 Genus Lifesciences 2 Marlex Pharmaceuticals, Inc. 2 Omnivium Pharmaceuticals Llc. 2 Remedyrepack Inc. 2 Teva Pharmaceuticals USA, Inc. 2 Aphena Pharma Solutions - Tennessee, LLC 1 CMP Pharma, Inc. 1 Mylan Institutional Inc. 1 Proficient Rx LP 1 Sandoz Inc 1

Isoniazid drug class (RxNorm)

Isoniazid belongs to the Antimycobacterial class.

Pharmacologic class Antimycobacterial
Drug family (ATC) Hydrazides

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 Isoniazid 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 1, 2019
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Isoniazid.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Isoniazid after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
27
Finished products in the current FDA directory
27
Companies listing them (makers, repackagers, distributors)
14
FDA labeler codes behind them ⓘ
15
Linked representative label ⓘ
Proficient Rx LP
Linked label effective
Nov 1, 2019
Composite sections available
17
Linked SPL Set ID
65e50989-d24c-4bb3-a041-d6aea2635ef1
Linked SPL Document ID
5c1e5064-9311-4161-a11f-1e006dd97bfb
Open the linked representative label on DailyMed ↗

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. Proficient Rx LP 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 →