How the dose is calculated
Tinidazole is dosed once daily in mg/kg. Giardiasis uses a single-day dose, while invasive amoebiasis uses the same daily dose continued for a short course (typically 3 days) — select the indication to see the correct course length.
Typical dosing by indication
| Indication | Dose | Frequency | Max |
|---|---|---|---|
| Giardiasis | 50 mg/kg once, single dose | single dose (day 1 only) | 2000 mg |
| Amoebiasis | 50 mg/kg once daily | once daily for 3 days | 2000 mg/day |
Clinical use
- Tinidazole's longer half-life than metronidazole allows shorter courses — a single dose for giardiasis versus metronidazole's multi-day, multiple-times-daily regimen — which can improve adherence.
- Effective for invasive amoebiasis (including amoebic liver abscess) as a shorter alternative to metronidazole, typically given once daily for 3 days.
- Shares metronidazole's disulfiram-like interaction with alcohol — avoid alcohol during treatment and for at least 72 hours after the last dose (longer than metronidazole's 48-hour window, given tinidazole's longer half-life).
- Metallic taste and nausea are common but harmless side effects worth mentioning to patients in advance.
Frequently asked questions
What is tinidazole used for?
Tinidazole treats Giardia lamblia infection (giardiasis) and invasive amoebiasis, including amoebic liver abscess, usually with a shorter course than metronidazole for the same conditions.
What is tinidazole 500mg used for?
500 mg is the standard adult tablet strength — the tablets are combined to reach the calculated weight-based dose (e.g. 2 g for giardiasis is four 500 mg tablets). It's used for the same indications as tinidazole generally: giardiasis and invasive amoebiasis (including amoebic liver abscess), and it's also used for bacterial vaginosis and as part of some H. pylori eradication regimens.
How should tinidazole 500mg be taken?
Taken orally with food to reduce nausea, swallowed whole rather than chewed or crushed, at the calculated dose and frequency for the specific indication (e.g. a single dose for giardiasis, or once daily for a short course for amoebiasis). Avoid alcohol during treatment and for at least 72 hours after the last dose. Always confirm the exact regimen and duration for the indication being treated.
Why is tinidazole only a single dose for giardiasis?
Its longer half-life than metronidazole means a single dose maintains effective drug levels long enough to clear Giardia lamblia, avoiding the multi-day course metronidazole requires for the same infection.
Can I drink alcohol while taking tinidazole?
No — like metronidazole, tinidazole can cause a disulfiram-like reaction with alcohol (flushing, nausea, rapid heartbeat). Avoid alcohol during treatment and for at least 72 hours after the last dose.
Is tinidazole the same as metronidazole?
They're related 5-nitroimidazole antibiotics with a similar spectrum against anaerobes and protozoa, but tinidazole's longer half-life allows shorter courses for some indications, such as a single dose for giardiasis.
References
- Centers for Disease Control and Prevention. Giardiasis — Treatment Guidance.
- British National Formulary for Children (BNFc) — Tinidazole.
- World Health Organization. Model Formulary — Tinidazole.