From £23.81 per pack.
Source: NHS Drug Tariff (what the NHS pays per pack), 7 Nov 2026. What you pay at the counter can be higher (pharmacy fees, insurance).
Prices in other countries are not what you will pay where you live; they show how prices compare.
In United Kingdom, Isoniazid costs from £23.81 per pack (NHS Drug Tariff (what the NHS pays per pack)).
Ask the pharmacist for a generic version with the same active ingredient and strength: it works the same and usually costs much less. Compare a few licensed pharmacies, and never buy medicine from unlicensed sellers to save money.
Check the registration number on the pack with PillVera, look at the expiry date, and buy from a licensed or verified pharmacy. A price far below everyone else's is a warning sign.