Isoniazid — Membership Pricing

Other medications in Infections

• Itraconazole
• Ketoconazole
• Lamivudine
• Ledipasvir
• Linezolid
• Loracarbef
• Meropenem
• Minocycline

What Isoniazid is approved for (FDA label)

Isoniazid tablets, USP are 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 tablets, USP are 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 parenthesis): Persons with human immunodeficiency virus (HIV) infection (greater than or equal to 5 mm) and persons with risk factors for HIV infection whose HIV infection status is unknown but who are suspected of having HIV infection.

Source: Read the full FDA label on DailyMed. Label effective date: September 4, 2026.

Excerpt from the FDA-approved prescribing information. This is not medical advice; talk to your doctor or pharmacist.

Boxed warning for Isoniazid (FDA label)

WARNING 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.

Source: FDA prescribing information (DailyMed). Set ID: 6dab7b7b-a3a9-47ef-b423-134bc6970d8b. SPL document ID: 5aa9218d-82a2-5923-e063-6394a90ad1c1. Label effective date: September 4, 2026. Read the full label.

Excerpt from the FDA-approved prescribing information. This is not medical advice; talk to your doctor or pharmacist.

Adverse reactions for Isoniazid (FDA label)

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". Other neurotoxic effects, which are uncommon with conventional doses, are convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment and toxic psychosis. 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 ).

Source: FDA prescribing information (DailyMed). Set ID: 6dab7b7b-a3a9-47ef-b423-134bc6970d8b. SPL document ID: 5aa9218d-82a2-5923-e063-6394a90ad1c1. Label effective date: September 4, 2026. Read the full label.

Excerpt from the FDA-approved prescribing information. This is not medical advice; talk to your doctor or pharmacist.

Contraindications for Isoniazid (FDA label)

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.

Source: FDA prescribing information (DailyMed). Set ID: 6dab7b7b-a3a9-47ef-b423-134bc6970d8b. SPL document ID: 5aa9218d-82a2-5923-e063-6394a90ad1c1. Label effective date: September 4, 2026. Read the full label.

Excerpt from the FDA-approved prescribing information. This is not medical advice; talk to your doctor or pharmacist.

Drug interactions for Isoniazid (FDA label)

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.

Source: FDA prescribing information (DailyMed). Set ID: 6dab7b7b-a3a9-47ef-b423-134bc6970d8b. SPL document ID: 5aa9218d-82a2-5923-e063-6394a90ad1c1. Label effective date: September 4, 2026. Read the full label.

Excerpt from the FDA-approved prescribing information. This is not medical advice; talk to your doctor or pharmacist.