Isoniazid: uses, dosing, side effects & brands
Isoniazid is an antimycobacterial sold in the U.S. under 4 brand and generic names, for tuberculosis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Antimycobacterial
- Treats (across its forms)
- Tuberculosis
- Available as
- Tablet · Injectable · Solution · Syrup
- Sold as
- 4 products — Nydrazid, Isoniazid and Laniazid, and others
- Prescription?
- Prescription only
- Generic available?
- Yes
- What the pharmacy pays
- about $97 for a 30-count supply — not your price
- Boxed warning
- Boxed warning
How Laniazid is dosed
From the FDA label for Laniazid (application ANDA089776). Other isoniazid products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
(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…
Everything below is the FDA label for Laniazid (tablet). Isoniazid is also sold as injectable, solution and syrup, and those are different medicines to take — follow the label for the one you were prescribed.
Laniazid side effects
The most frequent reactions are those affecting the nervous system and the liver. Nervous System Reactions Peripheral neuropathy is the most common toxic effect. It is dose-related, occurs most often in the malnourished and in those predisposed to neuritis (e.g., alcoholics and diabetics) and is usually preceded by paresthesias of the feet and hands. The incidence is higher in "slow inactivators". Cerebellar syndrome, which may include abnormal motor coordination manifesting as gait, trunk, and limb ataxia, dysmetria and dysdiadochokinesia, intention tremor, dysarthria, or nystagmus, have been reported in post marketing case reports (see WARNINGS ). Other neurotoxic effects, which are uncommon with conventional doses, are convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment and toxic psychosis. Hepatic Reactions See boxed warning . Elevated serum transaminase (SGOT; SGPT), bilirubinemia, bilirubinuria, jaundice and occasionally severe and sometimes fatal hepatitis. The common prodromal symptoms of hepatitis are anorexia, nausea, vomiting, fatigue, malaise and weakness. Mild hepatic dysfunction, evidenced by mild and transient elevation of serum transaminase levels occurs in 10 to 20 percent of patients taking isoniazid. This abnormality usually appears in the first 1 to 3 months of treatment but can occur at any time during therapy. In most…
Who shouldn’t take Laniazid
Isoniazid is contraindicated in patients who develop severe hypersensitivity reactions, including drug- induced hepatitis; previous isoniazid-associated hepatic injury; severe adverse reactions to isoniazid such as drug fever, chills, arthritis; and acute liver disease of any etiology.
Every isoniazid product we track (4)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 72/100 | Prescription | Tablet | Generic | $97 | View → | |
| 2 | 70/100 | Prescription | Injectable | Generic | $97 | View → | |
| 3 | Not yet rated | Prescription | Tablet | Generic | $97 | View → | |
| 4 | Not yet rated | Prescription | Injectable | Generic | $97 | View → |
What isoniazid pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
Combination products containing isoniazid
A combination is a different drug — different dosing, different warnings. It is listed here so you can find it, not so you can substitute it.
How long isoniazid keeps
No isoniazid label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
Does isoniazid expire? The in-use limits and storage rules from its labelsIsoniazid and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for isoniazid: levels in milk, effects in breastfed infants, and the drugs it would consider insteadBecause of the low levels of isoniazid in breastmilk and safe administration directly to infants, it is unlikely to cause adverse reactions in infants, but infants should be monitored for rare instances of jaundice. Giving the maternal once-daily dose before the infant's longest sleep period will decrease the dose the infant receives. The amount of isoniazid in milk is insufficient to treat tuberculosis in the breastfed infant. If breastfed infants are treated with isoniazid, they should also receive pyridoxine 1 mg/kg daily. The Centers for Disease Control and Prevention and other professional organizations state that breastfeeding should not be discouraged in women taking isoniazid.
National Institute of Child Health and Human Development, record revised August 15, 2024. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about isoniazid
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 17,282 reports naming isoniazid, and the FDA flagged 91% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- pyrexia1,265 reports
- nausea1,047 reports
- drug-induced liver injury884 reports
- drug reaction with eosinophilia and systemic symptoms768 reports
- headache704 reports
- vomiting693 reports
- malaise586 reports
- anaemia581 reports
Read these as a signal, not a rate. A report does not mean isoniazid caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved August 25, 2026.
Related calculators
Frequently asked questions
What is Laniazid?
Laniazid (Isoniazid) is an antimycobacterial used to treat Tuberculosis.
What kind of drug is isoniazid?
The FDA classifies isoniazid as an antimycobacterial. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take isoniazid with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run isoniazid against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is isoniazid sold under?
We track 4 isoniazid-containing products in the U.S.: Nydrazid, Isoniazid, Laniazid and Rimifon. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does isoniazid come in?
Across the brands we track, isoniazid is currently marketed as tablet, injectable, solution and syrup, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic isoniazid?
Yes. Our catalog lists 2 generic isoniazid products alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.
Cite this page
- APA
- pharmaranks. (2026, July 24). Isoniazid: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/isoniazid
- MLA
- “Isoniazid: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/isoniazid.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for isoniazid on DailyMed (NIH) ↗ — including its boxed warning in full.