Metronidazole 2g Single Dose (5 x 400mg Tablets)

The metronidazole 2g single dose treats bacterial vaginosis (BV) with one dose of antibiotic: you take 5 metronidazole 400mg tablets together, once. It is an alternative to the 7-day course of metronidazole tablets for people who would find a single dose easier. At Bury Healthcare Online we supply it to people who have had BV diagnosed before and recognise the same symptoms. You complete a short online consultation, and a UK prescriber checks your answers before anything is dispatched.

How to get the metronidazole single dose online

1. Select Start Consultation. Choosing the single dose is a preference: the final decision is made with your prescriber.
2. Complete a short online consultation about your symptoms, your health and any medicines you take. It takes about 5 minutes.
3. A UK prescriber checks your answers against your NHS Summary Care Record (with your consent) or with a short phone call. After you order, we also ask you to confirm your identity online. The prescriber may suggest a different BV treatment or decide treatment isn’t suitable. If it isn’t suitable, you get a full refund.
4. Approved orders are dispatched in plain packaging from our GPhC-registered pharmacy in Bury (GPhC 1126145).

We supply one course per order. With your consent, we send your GP a short summary of the treatment.

Who this service is for

This service is for people aged 18 to 64 who have had BV diagnosed before by a doctor, nurse or sexual health clinic and have the same symptoms again, such as a thin white or grey discharge with a fishy smell. It isn’t suitable if:

• this is the first time you’ve had these symptoms (you need a swab test to confirm it’s BV)
• you are pregnant, could be pregnant or are breastfeeding (the high single dose is not recommended in pregnancy)
• you have had BV 3 or more times in the last 12 months
• you have pain in your lower tummy or pelvis, a fever, bleeding between periods or after sex, or sores or blisters

A sexual health clinic or your GP can help in these situations. Itching and a thick white discharge are more likely to be thrush, which metronidazole doesn’t treat.

Single dose or 7-day course?

Both use the same medicine. The single dose is quicker and there is no course to remember. However, it is more likely to make you feel sick, and some studies suggest it may be slightly less effective than the 7-day course. If you have had sickness with metronidazole before, the 7-day course, Zidoval gel or clindamycin cream may suit you better.

How to take the single dose

• Take all 5 tablets (2g) together, once, with a glass of water.
• Take them during or just after a meal to reduce the chance of feeling sick.
• Swallow the tablets whole. Don’t chew them.
• If you are sick within a few hours of taking the tablets, contact us or a pharmacist for advice.

Metronidazole and alcohol

Don’t drink alcohol on the day you take the tablets and for at least 48 hours (2 days) afterwards. Drinking can make you feel very unwell, with sickness, stomach pain, hot flushes, a fast heartbeat and a headache. Check labels too, as some medicines and mouthwashes contain alcohol.

Who shouldn’t take metronidazole

Don’t take metronidazole if you are allergic to metronidazole or similar medicines (nitroimidazoles). Tell your prescriber if you:

• have liver problems, a condition affecting your nervous system, or Cockayne syndrome
• are on dialysis
• are trying for a baby
• think you won’t be able to avoid alcohol for 2 days

Some medicines can affect metronidazole, or be affected by it. Tell your prescriber if you take disulfiram (Antabuse), warfarin, lithium, phenytoin or phenobarbital, ciclosporin, busulfan, fluorouracil, or any medicine that affects your heart rhythm.

Side effects

Common side effects include feeling or being sick, diarrhoea, and a metallic taste or furry tongue. These are more likely with the single high dose. Contact a doctor if being sick or diarrhoea lasts more than 24 hours.

Metronidazole can occasionally cause drowsiness, dizziness or problems with your vision. Don’t drive or use machinery if this happens.

Call a doctor or NHS 111 straight away if you get yellow skin or eyes, unexpected infections, mouth ulcers, bruising or bleeding gums, severe stomach pain that may spread to your back, or blurred or double vision.

Compare prescription BV treatments

Prices include the consultation. Prescription medicines are supplied only after a prescriber has reviewed your consultation. Prefer to start without antibiotics? Lactic acid products such as Balance Activ BV gel are available without a prescription.

Important safety information

Call 999 or go to A&E if you have a headache, high temperature and stiff neck together with sensitivity to light, confusion or hallucinations, or signs of a serious allergic reaction, such as swelling of the lips, mouth or throat, difficulty breathing, or a widespread rash.

This page is a summary. Always read the patient information leaflet supplied with your medicine. See a sexual health clinic or GP if your symptoms haven’t gone within a week of treatment, or if they keep coming back. You can report side effects through the MHRA Yellow Card scheme.

Medically reviewed by Hassan Khan, MPharm, Independent Prescriber — Superintendent Pharmacist, Bury Healthcare Online (GPhC-registered pharmacy 1126145). Last reviewed: October 2026. Information checked against the UK Summary of Product Characteristics.

Read our BV treatment guide to compare prescription and non-prescription BV treatments, and to find out more about symptoms and when to see a GP.

Frequently asked questions