Isoniazid

Nydrazid, Laniazid, INH

Antimycobacterial • Isonicotinic acid hydrazide

Premium

Hepatotoxic

Half-life

1-4 hours (varies with acetylator status)

Protein Binding

0-10%

Metabolized By

NAT2 (N-acetyltransferase)

External

Drugs.com

Boxed warning

Fatal hepatitis risk — monitor LFTs monthly; increased risk with age, alcohol use, and pre-existing liver disease

Clinical alerts

Boxed warning

1 boxed warning

Hepatotoxic

Monitor liver function

Mechanism of action

Inhibits mycolic acid synthesis in mycobacterial cell walls; potent CYP2E1 inhibitor

Recorded indications

From the drug index — may include conditions studied rather than approved indications

·Tuberculosis
·Tuberculosis, Pulmonary
·Tuberculosis, Lymph Node
·Mycobacterium Tuberculosis
·Tuberculosis, Latent

Interactions

1 curated · 1 major or contraindicated · select a row for management

Interacting drug	Severity	Effect
rifampicin	major	Increased risk of drug-induced hepatitis, particularly in slow acetylators, elderly, and patients with pre-existing liver disease.

Common adverse effects

Peripheral neuropathy
Hepatitis
Nausea
Rash
Elevated LFTs

Food, alcohol & herbal

Food

Avoid tyramine-rich foods (aged cheese, smoked meats, soy sauce) — MAO inhibition risk
Avoid histamine-rich foods (tuna, mackerel) — may cause flushing/headache
Take on empty stomach

Alcohol · major

Significantly increased hepatotoxicity risk; daily alcohol use is a major risk factor for isoniazid-induced liver injury

Herbal

Kava (major) — Additive hepatotoxicity risk

Pharmacokinetics

Half-life: 1-4 hours (varies with acetylator status)
Protein binding: 0-10%
Metabolised by: NAT2 (N-acetyltransferase)
Inhibits: CYP2E1, CYP2C19, CYP3A4
Induces: CYP2E1 (chronic)

Pregnancy & lactation

Not recorded for Isoniazid. Absence here means this database does not hold a category — not that the drug is safe in pregnancy or breastfeeding.

Sources

Assembled from: drug index, curated drug database, curated interaction pairs.

Not a substitute for clinical judgement

Isoniazid

Nydrazid, Laniazid, INH

Antimycobacterial • Isonicotinic acid hydrazide

Premium

Hepatotoxic

Half-life

1-4 hours (varies with acetylator status)

Protein Binding

0-10%

Metabolized By

NAT2 (N-acetyltransferase)

External

Drugs.com

Boxed warning

Fatal hepatitis risk — monitor LFTs monthly; increased risk with age, alcohol use, and pre-existing liver disease

Clinical alerts

Boxed warning

1 boxed warning

Hepatotoxic

Monitor liver function

Mechanism of action

Inhibits mycolic acid synthesis in mycobacterial cell walls; potent CYP2E1 inhibitor

Recorded indications

From the drug index — may include conditions studied rather than approved indications

·Tuberculosis
·Tuberculosis, Pulmonary
·Tuberculosis, Lymph Node
·Mycobacterium Tuberculosis
·Tuberculosis, Latent

Interactions

1 curated · 1 major or contraindicated · select a row for management

Interacting drug	Severity	Effect
rifampicin	major	Increased risk of drug-induced hepatitis, particularly in slow acetylators, elderly, and patients with pre-existing liver disease.

Common adverse effects

Peripheral neuropathy
Hepatitis
Nausea
Rash
Elevated LFTs

Food, alcohol & herbal

Food

Avoid tyramine-rich foods (aged cheese, smoked meats, soy sauce) — MAO inhibition risk
Avoid histamine-rich foods (tuna, mackerel) — may cause flushing/headache
Take on empty stomach

Alcohol · major

Significantly increased hepatotoxicity risk; daily alcohol use is a major risk factor for isoniazid-induced liver injury

Herbal

Kava (major) — Additive hepatotoxicity risk

Pharmacokinetics

Half-life: 1-4 hours (varies with acetylator status)
Protein binding: 0-10%
Metabolised by: NAT2 (N-acetyltransferase)
Inhibits: CYP2E1, CYP2C19, CYP3A4
Induces: CYP2E1 (chronic)

Pregnancy & lactation

Not recorded for Isoniazid. Absence here means this database does not hold a category — not that the drug is safe in pregnancy or breastfeeding.

Sources

Assembled from: drug index, curated drug database, curated interaction pairs.

Not a substitute for clinical judgement

Isoniazid Drug Profile | PharmaGraphX