Isoniazid: uses, side effects & brands

Written & medically reviewed by Dr. Sanjay Anbu, MBBS · Last reviewed 5 November 2026

Isoniazid is a core TB drug; vitamin B6 is given to prevent nerve effects. It belongs to the Anti-tuberculosis (TB) medicine group. These treat tuberculosis. TB always needs a combination of drugs for several months to cure it and prevent resistance.

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Drug type — dosing is set by your doctor

Measure	Range
Drug class	Anti-tuberculosis (TB) medicine
Type	Prescription
Dose	Individual — ask your doctor or pharmacist

What it is used for

Core medicine for treating active tuberculosis with other TB drugs
Used alone to prevent TB in people with latent TB infection
Used to protect close contacts and people with weak immunity, such as HIV

Common brand names

India: Isokin, Solonex
Worldwide: (isoniazid/INH brands)

Common side effects

Tingling or numbness in hands and feet
Nausea or loss of appetite
Raised liver enzymes
Rash

Before taking it — precautions

Vitamin B6 (pyridoxine) is usually given alongside to protect the nerves
Avoid alcohol and tell your doctor about liver disease; liver checks may be needed
Tell your doctor if you take epilepsy medicines, as levels can change

When to see a doctor urgently

Yellow skin or eyes, dark urine, or unusual tiredness and vomiting (urgent)
Severe numbness, burning or weakness in the limbs
Severe rash or fever

Not a prescription — no dose shown. The right dose of isoniazid depends on age, weight, kidney/liver function and the condition, so MedDroid does not show a dose here. Always get your dose from a doctor or pharmacist and the leaflet inside the pack. General educational information only.

Frequently asked questions

Why do I need vitamin B6 with isoniazid?

Isoniazid can lower vitamin B6 and cause nerve damage; taking B6 helps prevent this.

Can I drink alcohol?

Avoid alcohol, because it raises the risk of liver damage with isoniazid.

Why is it given to people without TB symptoms?

It can treat hidden (latent) TB infection so that it does not become active disease later.

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Sources & further reading

Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.