Prescription medicine
Isoniazid First approved as Nydrazid
Isoniazid (Nydrazid) is a prescription medicine with an FDA approval on record since 1952. FDA's NDC Directory lists it from 14 generic labelers, and pharmacies paid $3.40 per isoniazid 300 mg tablet in the October 7, 2026 NADAC survey.
- Generic listed
- Boxed warning
Check it at the source: the isoniazid FDA label on DailyMed (effective July 8, 2025, OMNIVIUM PHARMACEUTICALS LLC.); the NDA 8662 record on Drugs@FDA; every isoniazid label on DailyMed.
Highlights of the record
FDA label of July 8, 2025; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026; NADAC October 7, 2026
Severe and sometimes fatal hepatitis associated with isoniazid therapy has been reported and may occur or may develop even after many months of treatment. The risk of developing hepatitis is age related. Approximate case rates by age are: less than 1 per 1,000 for persons under 20 years of age, 3 per 1,000 for persons in the 20 to 34 year age group, 12 per 1,000 for persons in the 35 to 49 year age group, 23 per 1,000 for persons in the 50 to 64 year age group and 8 per 1,000 for persons over 65 years of age. The risk of hepatitis is increased with daily consumption of alcohol. Precise data to provide a fatality rate for isoniazid-related hepatitis is not available; however, in a U.S. Public Health Service Surveillance Study of 13,838 persons taking isoniazid, there were 8 deaths among 174 cases of hepatitis. Therefore, patients given isoniazid should be carefully monitored and interviewed at monthly intervals. For persons 35 and older, in addition to monthly symptom reviews, hepatic enzymes (specifically, AST and ALT (formerly SGOT and SGPT, respectively)) should be measured prior to starting isoniazid therapy and periodically throughout treatment. Isoniazid-associated hepatitis usually occurs during the first three months of treatment. Usually, enzyme levels return to normal despite continuance of drug, but in some cases progressive liver dysfunction occurs. […]
Used for
From the label: indications and usageIsoniazid is recommended for all forms of tuberculosis in which organisms are susceptible.
Forms and strengths
- 100 mg
- 300 mg
- 50 mg/5ml
- 100 mg/ml
Tablet; solution; injection (solution).
On the market
- Earliest approval on file
- September 29, 1952 Nydrazid, Sandoz; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 30 first November 13, 1970; 5 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 14 of which 14 under generic applications, 0 under brand applications, repackagers included
Supply and safety
- Pharmacy cost (NADAC)
- $3.40 per tablet Isoniazid 300 mg tablet
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- 2 since 2012 0 Class I among all firms' recalls; latest May 20, 2014; 1 more by firms not listed as its makers
- FAERS reports
- 16,105 through July 30, 2026
What is isoniazid used for?
From the label: indications and usageIsoniazid is recommended for all forms of tuberculosis in which organisms are susceptible. However, active tuberculosis must be treated with multiple concomitant anti-tuberculosis medications to prevent the emergence of drug resistance. Single-drug treatment of active tuberculosis with isoniazid, or any other medication is inadequate therapy. Isoniazid is recommended as preventive therapy for the following groups, regardless of age. (Note: the criterion for a positive reaction to a skin test (in millimeters of induration) for each group is given in parentheses): 1. […]
FDA pharmacologic class: Antimycobacterial.
Source: FDA drug label (isoniazid), OMNIVIUM PHARMACEUTICALS LLC., effective July 8, 2025 (SPL set 35400f1d-fd25-4bfa-a382-ac390e21bf2e), via openFDA; the full label on DailyMed
Is there a generic for isoniazid (Nydrazid)?
The FDA approved the first generic isoniazid on November 13, 1970. 30 generic applications are approved; 5 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 isoniazid from 14 labelers under a generic (ANDA) application. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it.
- 1952 earliest approval on file
- 1970 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 isoniazid (Nydrazid)?
In CMS's NADAC survey of October 7, 2026, pharmacies paid $3.40 per Isoniazid 300 mg tablet, up 19% from $2.86 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.
- Isoniazid 300 mg tablet (generic)
| Strength and form | Brand or generic | Pharmacy cost | 30 tablets, or one pen or vial | 12-month change |
|---|---|---|---|---|
| Isoniazid 100 mg tablet | Generic | $1.73 per tablet | $51.97 | +8% |
| Isoniazid 300 mg tablet | Generic | $3.40 per tablet | $102.06 | +19% |
Source: CMS National Average Drug Acquisition Cost (NADAC) survey, October 7, 2026: what retail pharmacies paid per unit; not a counter price
Has isoniazid been recalled?
The FDA's Enforcement Report lists 3 recalls naming isoniazid since 2012: 0 Class I (the most serious), 3 Class II, 0 Class III; 0 still ongoing. 1 of them is by a firm that FDA's NDC Directory does not list as a maker of isoniazid and that holds no application for it in Drugs@FDA, such as compounding pharmacies or bulk-ingredient suppliers; the recall notice names the product recalled. A recall names products and lots, not every product of the medicine.
| Started | Class | Company | Reason |
|---|---|---|---|
| May 20, 2014 | Class II | West-Ward Pharmaceutical Corp. | Failed Dissolution Specifications: Stability lots cannot support dissolution past the 36 month time point. |
| July 2, 2013 | Class II | Aidapak Services, LLC not a listed maker | Labeling: Label Mixup: ISONIAZID, Tablet, 300 mg may have potentially been mislabeled as one of the following drugs: hydrOXYzine PAMOATE, Capsule, 100 mg, NDC … |
| December 4, 2012 | Class II | West-ward Pharmaceutical Corp. | Failed Dissolution Specifications; 36 month stability timepoint |
Source: FDA Enforcement Report (drug recalls) via openFDA, through October 8, 2026
What does the isoniazid label say about other medicines?
The isoniazid label names 6 other medicines in its interaction, contraindication or warning sections. The labels of 40 other medicines name isoniazid. 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 |
|---|---|---|
| Acetaminophen | drug interactions | Acetaminophen A report of severe acetaminophen toxicity was reported in a patient receiving isoniazid. |
| Carbamazepine | drug interactions | Carbamazepine Isoniazid is known to slow the metabolism of carbamazepine and increase its serum levels. |
| Ketoconazole | drug interactions | Ketoconazole Potential interaction of ketoconazole and isoniazid may exist. |
| Phenytoin | drug interactions | Phenytoin Isoniazid may increase serum levels of phenytoin. |
| Rifampin | drug interactions | When ketoconazole is given in combination with isoniazid and rifampin the AUC of ketoconazole is decreased by as much as 88% after 5 months of concurrent isoniazid and rifampin therapy 4 . |
| Theophylline | drug interactions | Theophylline A recent study has shown that concomitant administration of isoniazid and theophylline may cause elevated plasma levels of theophylline, and in some instances a slight decrease in the elimination of isoniazid. |
Other labels that name isoniazid
- Bacillus calmette-guerin substrain tice live antigen
- Bedaquiline
- Carbidopa
- Dexamethasone
- Disulfiram
- Folic acid
- Foscarbidopa and foslevodopa
- Glimepiride
- Glipizide
- Hydrocortisone
- Insulin aspart
- Insulin degludec
- Insulin detemir
- Insulin glargine
- Insulin glulisine
- Insulin human
- Insulin lispro
- Levodopa
- Metformin
- Methylprednisolone
- Multiple vitamins
- Prednisolone
- Propranolol
- Repaglinide
- Rifapentine
- Triamcinolone
Source: FDA drug label (isoniazid), OMNIVIUM PHARMACEUTICALS LLC., effective July 8, 2025 (SPL set 35400f1d-fd25-4bfa-a382-ac390e21bf2e), via openFDA; the full label on DailyMed
What do FAERS reports show for isoniazid?
The FDA Adverse Event Reporting System holds 16,105 reports that list isoniazid among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 2,199 are coded as a death and 6,997 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 next?
- Other antimycobacterials
- the pharmacologic class, with prices and generics
- Isoniazid side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other