Anti-tuberculosis antibiotic
Last reviewed June 2026
Who is this for?
Isoniazid is an antibiotic specifically designed to fight tuberculosis (TB) bacteria. It works by stopping the TB germs from building their protective walls, which kills them off over time.
Inhibits mycobacterial cell wall synthesis by blocking mycolic acid production through inhibition of InhA (enoyl-ACP reductase) after hepatic activation to its active metabolite. This disrupts the integrity of the mycobacterial cell envelope, leading to bacterial cell death.
Prescription Required
You need a doctor's prescription to buy this drug.
Explore this drug
For active TB treatment, the usual adult dose is 300 mg (one 300 mg tablet) taken once daily on an empty stomach — ideally 1 hour before food or 2 hours after eating. Your doctor will combine it with other TB drugs. For TB prevention, the dose is also 300 mg once daily, usually for 6 to 9 months. Always follow your doctor's exact instructions and never stop early even if you feel better.
If you miss a dose, take it as soon as you remember. But if it is almost time for your next dose, skip the missed one and continue your normal schedule. Do not take two doses at once to make up for it.
Important for antibiotics
Always complete the full course even if you feel better. Stopping early can cause the infection to return and become drug-resistant.
Complete your full TB treatment course even if you feel fine — stopping early can cause drug-resistant TB which is much harder and more expensive to treat. Your doctor may prescribe vitamin B6 (pyridoxine) alongside isoniazid to prevent nerve problems — make sure you take it. Only buy your isoniazid from licensed pharmacies and not from roadside sellers, as fake or expired TB drugs are dangerous and can make the disease harder to cure.
Alcohol — drinking alcohol while on isoniazid greatly increases your risk of liver damage, so avoid alcohol completely during treatment. Paracetamol — using paracetamol regularly alongside isoniazid can also stress your liver, so use it sparingly and only when necessary. Antacids like aluminium hydroxide (commonly sold in Nigerian pharmacies) can reduce how well isoniazid works — take them at least 1 hour apart.
Check your specific combination
Is it safe to take Isoniazid with your other drugs?
Isoniazid can be used during pregnancy and breastfeeding when your doctor decides the benefit of treating or preventing TB outweighs the risks — always consult your doctor before taking it.
Store in a cool, dry place away from direct sunlight and heat — Nigerian weather can be very hot, so avoid storing it near windows or in your car. Keep the container tightly closed to protect from moisture, and always keep it out of the reach of children.
For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.
Names this drug is sold under — especially in Nigerian and West African pharmacies
Tap a brand for packaging, NAFDAC details and authenticity check
Counterfeit Drug Warning
Fake drugs are a serious problem in Nigeria. Always buy from a registered pharmacy. If the packaging looks different from what is described above, do not use it.
Dispensing Isoniazid?
Clinical tools built for Nigerian pharmacists — launching soon.