Tinidazole for BV: How It Compares to Metronidazole
Where tinidazole fits in UK practice, how it is dosed, and why its alcohol rule runs longer.
Part of the Bacterial Vaginosis condition guide.
Please note: Access Doctor does not supply tinidazole. We stock metronidazole tablets, Zidoval vaginal gel and Dalacin 2% cream for BV. This guide is here because tinidazole comes up regularly as an alternative and the information is hard to find in one place — not because we are offering it.
Key fact: Tinidazole is a close relative of metronidazole with a longer half-life. That allows shorter, once-daily courses — but it also means the alcohol restriction runs for 72 hours after the last dose rather than 48.
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Access Doctor provides metronidazole, Zidoval and Dalacin following a GPhC-regulated online consultation with our pharmacist independent prescribers.
See BV treatment options →What tinidazole is
Tinidazole is an antibiotic in the nitroimidazole class — the same family as metronidazole. It works the same way: it is inactive until it enters an organism living in low-oxygen conditions, where it is chemically reduced into a reactive form that damages bacterial DNA and kills the cell.
Because the mechanism is shared, the range of organisms it covers is essentially the same. It is used for bacterial vaginosis, trichomoniasis, giardiasis and amoebiasis. In the UK it is prescription-only and has been marketed under the brand name Fasigyn.
| Detail | |
|---|---|
| Drug class | Nitroimidazole — same class as metronidazole |
| Active against | Anaerobic bacteria and certain protozoa |
| Half-life | Roughly twice that of metronidazole |
| UK licensing for BV | Licensed, but not first-line in NICE guidance |
| Alcohol restriction | During the course and for at least 72 hours after |
| Availability | Prescription only; not supplied by Access Doctor |
Where it sits in UK practice
Tinidazole is licensed for bacterial vaginosis in the UK, but it is not what most women are given. NICE Clinical Knowledge Summaries point to metronidazole 400mg twice daily for five to seven days as the first-line option, with vaginal metronidazole gel or clindamycin cream as the main alternatives.
Tinidazole tends to appear in a few specific situations: where metronidazole has been poorly tolerated, where a prescriber has a particular reason to prefer once-daily dosing, or in settings following US guidance, where tinidazole features more prominently in CDC recommendations than in UK ones.
Why the UK and US differ here. The CDC lists tinidazole among its alternative regimens for BV, which is why American sources mention it far more often. UK practice has stayed with metronidazole as the default, partly through familiarity and cost and partly because there is no compelling evidence that tinidazole produces better outcomes.
Dosing for BV
Two regimens are used for bacterial vaginosis in non-pregnant adults. Both are taken with food.
| Regimen | Duration | Notes |
|---|---|---|
| Tinidazole 2g once daily | 2 days | Shortest option; four 500mg tablets taken together each day |
| Tinidazole 1g once daily | 5 days | Lower daily dose spread over longer; generally better tolerated |
The evidence suggests the longer, lower-dose regimen is more effective than a single 2g dose taken once. That mirrors what is seen with metronidazole, where the single 2g dose is less effective at preventing early recurrence and is not routinely recommended in UK practice.
Always follow your own prescription label. Tinidazole is used at different doses for different conditions — the regimen for giardiasis is not the regimen for BV. If the label differs from anything on this page, follow the label and ask your pharmacist.
Tinidazole vs metronidazole
The two are close enough that the comparison comes down to practicalities rather than effectiveness.
| Metronidazole | Tinidazole | |
|---|---|---|
| Class | Nitroimidazole | Nitroimidazole |
| UK first-line for BV | Yes | No |
| Typical course | 400mg twice daily, 5–7 days | 2g once daily for 2 days, or 1g once daily for 5 days |
| Doses per day | Two | One |
| Half-life | Around 8 hours | Roughly double |
| Alcohol restriction after last dose | 48 hours | At least 72 hours |
| Nausea and metallic taste | Common | Reported, sometimes described as milder |
| Vaginal formulation available | Yes — Zidoval gel | No |
| Cost and availability in the UK | Widely stocked, inexpensive | Less commonly stocked |
Where tinidazole may appeal
Once-daily dosing over two to five days is simpler than twelve-hourly for a week, and some people find it easier on the stomach.
Where it does not
The longer alcohol restriction, no vaginal formulation, patchier UK availability, and no clear cure-rate advantage.
The longer alcohol rule
This is the most practically important difference and the one most often missed.
Avoid alcohol during a tinidazole course and for at least 72 hours after the final dose. Because tinidazole persists in the body longer than metronidazole, the window extends beyond the 48 hours that applies to metronidazole. The reaction is the same — flushing, throbbing headache, severe nausea, vomiting and palpitations.
The mechanism is identical: nitroimidazoles interfere with the enzyme that clears acetaldehyde, a by-product of alcohol metabolism, and it is the build-up of acetaldehyde that produces the symptoms. The same hidden sources apply too — alcohol-containing mouthwashes, some cough and cold liquids, and certain tonics. Our guide to how to take metronidazole covers the rule and its hidden sources in full, and the principle transfers directly.
Side effects and cautions
Because the two drugs share a class, the side effect profile is broadly the same as for metronidazole.
- Common: nausea, metallic or bitter taste, reduced appetite, headache and mild abdominal discomfort.
- Less common: dizziness, tiredness, and darkened urine, which is harmless.
- Stop and seek advice: numbness or tingling in the hands or feet, severe or bloody diarrhoea, seizures, unexplained bruising or bleeding, or a rash with facial swelling or breathing difficulty.
- Interactions: the same ones that matter for metronidazole, including warfarin, lithium, phenytoin and disulfiram.
- Avoid if: you are allergic to any nitroimidazole, have a blood disorder, or have a history of neurological conditions without specialist advice.
- Pregnancy: generally avoided, particularly in the first trimester.
The full detail on nitroimidazole side effects, the interaction table and what warrants stopping is in metronidazole side effects and warnings — the great majority of it applies equally to tinidazole.
Pregnancy and breastfeeding. Tinidazole is generally avoided in pregnancy. If you are pregnant with BV symptoms, see BV in pregnancy and contact your GP or midwife rather than seeking treatment online.
If metronidazole has not suited you
Most people looking into tinidazole have arrived there because metronidazole caused nausea or the alcohol restriction was impractical. On both counts there are options more readily available in the UK, and in most cases better suited to the problem.
1
If oral metronidazole made you nauseated
A vaginal preparation is the more reliable answer. Zidoval gel delivers the same drug locally with minimal systemic absorption, so nausea and metallic taste are far less of a problem. Tinidazole, being oral and in the same class, does not reliably solve this.
2
If the alcohol restriction is the obstacle
Dalacin 2% cream contains clindamycin, a different class entirely, and has no alcohol restriction at all. Tinidazole moves in the wrong direction here, extending the window to 72 hours.
3
If you want the shortest possible course
Zidoval is five nights and Dalacin is seven. Tinidazole's two-day regimen is shorter, but the trade-off is a much higher single daily dose and a longer alcohol window afterwards.
4
If episodes keep returning
Switching between similar antibiotics is unlikely to be the answer. Recurrent BV is managed with extended courses, suppressive twice-weekly gel and trigger management — see recurrent BV.
A side-by-side comparison of the three options we do supply, mapped against circumstances like alcohol, latex condoms and oral intolerance, is in BV treatment options compared.
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Start a BV consultation →Frequently Asked Questions
Is tinidazole used for BV in the UK?
Tinidazole is licensed for bacterial vaginosis in the UK but is not the usual first-line choice. NICE guidance points to metronidazole first, and tinidazole tends to be used where metronidazole has not been tolerated or where a prescriber has a specific reason to prefer it.
What is the dose of tinidazole for BV?
UK dosing for bacterial vaginosis in non-pregnant adults is 2g once daily for two days, or 1g once daily for five days, both taken with food. The longer, lower-dose regimen appears more effective than a single 2g dose.
Is tinidazole better than metronidazole for BV?
Not clearly better in terms of cure rates. Tinidazole has a longer half-life, which allows once-daily dosing over a shorter course, and some people find it easier on the stomach. Against that, its alcohol restriction lasts longer and it is less commonly stocked.
How long must I avoid alcohol after tinidazole?
Longer than with metronidazole. Alcohol should be avoided during the course and for at least 72 hours after the final dose, because tinidazole stays in the body longer. The reaction is the same unpleasant flushing, nausea and palpitations.
Can I take tinidazole if metronidazole made me feel sick?
It is one option a prescriber may consider, and some people tolerate it better. Both are nitroimidazoles, though, so side effects can overlap. A vaginal preparation such as Zidoval gel or Dalacin cream is often the more reliable way to avoid systemic side effects.
Can I take tinidazole in pregnancy?
Tinidazole is generally avoided in pregnancy, particularly in the first trimester. BV in pregnancy should be managed by your GP, midwife or a sexual health clinic rather than through self-treatment or an online order.
Does Access Doctor supply tinidazole?
No. We supply metronidazole tablets, Zidoval vaginal gel and Dalacin 2% cream for BV. If a prescriber has recommended tinidazole specifically, you will need to obtain it through your GP or the service that recommended it.
Completing the treatment
We do not supply tinidazole, but the three treatments we do stock cover the situations that usually lead people to look for it — oral intolerance, the alcohol restriction, and a preference for a short course.
Bacterial vaginosis · Rx
Zidoval Vaginal Gel
Metronidazole 0.75% gel — five nights, with far less nausea than tablets.
View product →Bacterial vaginosis · Rx
Dalacin 2% Cream
Clindamycin vaginal cream — the option with no alcohol restriction.
View product →Bacterial vaginosis · Rx
Metronidazole 400mg Tablets
UK first-line oral antibiotic for BV, taken twice daily for five to seven days.
View product →Self-test · Pharmacy
Canestest Self-Test
Checks vaginal pH at home to help distinguish BV from thrush before you treat.
View product →References
- National Institute for Health and Care Excellence. Clinical Knowledge Summaries: Bacterial vaginosis. 2025. cks.nice.org.uk
- British National Formulary. Tinidazole. bnf.nice.org.uk
- Dickey LJ, Nailor MD, Sobel JD. Guidelines for the treatment of bacterial vaginosis: focus on tinidazole. International Journal of Women's Health. tandfonline.com
- Centers for Disease Control and Prevention. Sexually Transmitted Infections Treatment Guidelines: Bacterial Vaginosis. cdc.gov
- Electronic Medicines Compendium. Tinidazole 500mg Tablets — Summary of Product Characteristics. medicines.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.