Isoniazid: Side Effects, Uses & Monitoring
Isoniazid Tablets are recommended for all forms of tuberculosis in which organisms are susceptible.
- Data source
- FDA labeling via NIH DailyMed (label 2e09b1a5…)
- Label version
- current
- Last reviewed
- 2026
Reported adverse reactions
Reactions listed in current FDA labeling, with the highest frequency reported across summarized placebo-controlled trials.
No structured frequency data available in current labeling. Consult the official label.
Labeled uses (from FDA prescribing information)
Isoniazid Tablets 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 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. Preventive therapy may be considered for HIV infected persons who are tuberculin-negative but belong to groups in which the prevalence of tuberculosis infection is high. Candidates for preventive therapy who have HIV infection should have a minimum of 12 months of therapy. Close contacts of persons with newly diagnosed infectious tuberculosis (greater than or equal to 5 mm). In addition,…
Conditions associated with Isoniazid in labeling
Frequently Asked Questions
What is Isoniazid used for?
FDA labeling lists the approved uses shown above under "Labeled uses." This summary is informational; only a qualified prescriber can determine whether a medication is appropriate for you.
What are the most commonly reported side effects of Isoniazid?
Current labeling for this ingredient does not include a structured frequency table that we can reproduce. Review the official label linked below.
Does Isoniazid require lab monitoring?
Monitoring needs vary. Ask your healthcare provider whether any lab tests apply while taking Isoniazid.
Where does this information come from?
All clinical facts on this page were extracted from the current FDA-registered product labeling for this ingredient, published by manufacturers through NIH DailyMed. See the source link below.
Medical disclaimer: Educational content extracted from public FDA labeling. Not medical advice. Always consult a qualified healthcare professional before starting, stopping, or changing any medication.