Isoniazid

Anti-TB antibiotic
PRESCRIPTION ONLY IN INDIA

Isoniazid is a anti-TB antibiotic found in 1 medicine sold in India, such as R-Cinex 450. Below: what it is for, how it works, how to take it, side effects, interactions and pregnancy advice.

Also called: inh

What it is used for

Treats and prevents tuberculosis (TB).

How it works

A key TB antibiotic, used in combination treatment and alone to prevent TB.

How to take it

Usually once a day on an empty stomach, with vitamin B6 (pyridoxine) to protect nerves.

Common side effects

  • Nausea
  • Tingling in hands and feet

Get medical help straight away if

  • Yellow skin, dark urine, loss of appetite (liver)
  • Numbness

Be careful

Can cause tingling of hands and feet (vitamin B6 is usually given) and affect the liver. Never stop the course early.

Other medicines and interactions

Raises phenytoin and carbamazepine levels. Avoid alcohol (liver risk). Antacids reduce absorption.

Pregnancy and breastfeeding

Standard TB treatment is used in pregnancy (untreated TB is more dangerous) and while breastfeeding.

Combination medicines that contain Isoniazid (1)

R-Cinex 450

Common questions

What is Isoniazid used for?

Treats and prevents tuberculosis (TB).

How does Isoniazid work?

A key TB antibiotic, used in combination treatment and alone to prevent TB.

How should I take Isoniazid?

Usually once a day on an empty stomach, with vitamin B6 (pyridoxine) to protect nerves.

What are the side effects of Isoniazid?

Common: Nausea, tingling in hands and feet. Get help straight away for: Yellow skin, dark urine, loss of appetite (liver), numbness.

Does Isoniazid interact with other medicines?

Raises phenytoin and carbamazepine levels. Avoid alcohol (liver risk). Antacids reduce absorption.

Is Isoniazid safe in pregnancy and breastfeeding?

Standard TB treatment is used in pregnancy (untreated TB is more dangerous) and while breastfeeding.

Does Isoniazid need a prescription in India?

Yes. In India it is a prescription (Schedule H) medicine, so a pharmacist should sell it only with a doctor's prescription.

Which brands contain Isoniazid?

R-Cinex 450.

Sources and further reading

NHS (UK National Health Service) and MedlinePlus (US National Library of Medicine) are free, reviewed medicine guides. Brand names and doses there may differ from India.

Last reviewed 31 October 2026. Written by Satya Babu from standard prescribing information.

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For information only, not medical advice. This page is a plain-language summary written from standard prescribing information and the public guides linked below. Brands sometimes change their formula, so always check the composition printed on the pack. Doses here are typical adult doses; yours may differ. Do not start, stop or change a medicine without your doctor or pharmacist, and keep all medicines away from children. In an emergency, call 112 (India) or your local emergency number.