Metronidazole

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Reviewed on Jan 31, 2025. by Mr Craig Marsh Independent Prescriber Registered with GPhC (No. 2070724) Next review due on January 31, 2028.

Last updated on Jan 31, 2025.

Product info

Metronidazole is an antibiotic used to treat bacterial infections.
It can help clear bacterial vaginosis (BV) symptoms like itching, irritation and discharge.
The usual dose is two 400mg tablets a day.

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Prices include:

Express shipping
24 hour shipping by secure courier.
Consultation + Access to our clinicians
Ask our experts anything you like, any time you want.
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£35.95

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Metronidazole: essential info
Metronidazole: instructions
Important stuff you need to know
FAQ

What is Metronidazole?

Metronidazole is an antibiotic that’s used to treat bacterial infections. It’s prescribed for various conditions including rosacea, infected gums and bacterial vaginosis.

Metronidazole helps to restore the balance of bacteria in your vagina. Metronidazole is the active ingredient in the generic tablets and in the branded version Flagyl. The branded and generic version are made by different companies and come in slightly different packaging.

Metronidazole tends to be cheaper than Flagyl.

What are bacterial infections?

Bacterial vaginosis is a common infection that results in unusual vaginal discharge. It’s not a sexually transmitted infection (STI), but it can increase your risk of getting chlamydia.^[1]Any woman can get it, including transgender women, those in same sex relationships, and those who’ve never had sex.

Symptoms include a burning sensation when you pee, a grey or green discharge from the vagina and an unpleasant ‘fishy’ smell.

Bacterial vaginosis happens when the natural balance of bacteria in your vagina changes. This sometimes occurs when you have sex with a new partner, have an IUD fitted or use perfumed products around your genitals. The pH balance within the vagina is delicate and introducing anything that upsets the balance can cause infection to thrive.

How does Metronidazole work?

Bacterial infections exist in the body by entering a suitable environment and then reproducing. The cells do this by multiplying. The active ingredients in metronidazole pass into the bacteria cells and cause DNA damage, thus stopping the bacteria from growing and multiplying.^[2]Without the ability to multiply the infection weakens and the body uses its natural immune defences to clear up the remaining infection.

Your genitals need some ‘good bacteria’ to keep them healthy, but bacterial vaginosis is caused by the excessive growth of unwanted bacteria, and so the right balance needs to be restored.

What doses of Metronidazole are there?

There are three dosage sizes available: 200mg, 400mg and 500mg. The common prescription for bacterial vaginosis is one 400mg tablet taken twice a day.

Treated trusted sources:

NHS Health A to Z (2018). Bacterial vaginosis.
Sigeti, J.S., Guiney, D.G. and Davis, C.E. (1983). Mechanism of Action of Metronidazole on Bacteroides fragilis. Journal of Infectious Diseases, 148(6), pp.1083–1089.

This page was written by The Treated Content Team.

This page was medically reviewed by Mr Craig Marsh on January 31, 2025. Next review due on January 31, 2028.

How we source info.

When we present you with stats, data, opinion or a consensus, we’ll tell you where this came from. And we’ll only present data as clinically reliable if it’s come from a reputable source, such as a state or government-funded health body, a peer-reviewed medical journal, or a recognised analytics or data body. Read more in our editorial policy.

FAQ: Metronidazole

Have something specific you want to know? Search our info below, or ask our experts a question if you can’t find what you’re looking for.

How is Metronidazole different from other treatments for bacterial vaginosis?

Answer:

Some people don’t know that they’ve got bacterial vaginosis, and it often clears up on its own. For others, the symptoms can be unpleasant and recurring. Metronidazole is a popular and effective treatment^[1] for bacterial vaginosis, but there are alternative medications too.

Another common treatment is Zidoval, which is a branded version of Metronidazole. While Metronidazole comes as tablets, Zidoval is a gel containing 0.75% metronidazole (each g of gel contains 7.5mg of metronidazole) that’s applied directly inside the vagina (or neovagina for trans women) to treat bacterial vaginosis.

Dalacin is another topical treatment for bacterial vaginosis. Unlike Metronidazole, it’s a cream and contains a slightly different antibiotic called clindamycin phosphate. Dalacin is applied using a disposable plastic applicator to the vagina before you go to sleep. A course of Dalacin usually lasts three to five days.

As they all contain antibacterial agents, all of these options are only available on prescription. A clinician needs to mobitor their use to ensure they're safe for you to take and use correctly.

Can I get Metronidazole over the counter?

Answer:

No. All antibiotics need to be prescribed by a trained clinician. This is because all infections need to be monitored as they’re treated to ensure that they don’t spread or worsen.

When it comes to antibiotics, it’s important to ensure that you’re taking the right medication to treat the right infection. Our clinicians will chat to you and build up a full picture before prescribing the best treatment for your needs.

You can get tested through your GP, or at a sexual health clinic, for BV. Providing evidence of a positive result helps us choose the best medication for you. If you haven’t been tested yet, we can still offer treatments if there are enough indicators that you have bacterial vaginosis.

Is Metronidazole similar to any other treatments?

Answer:

As well as being available as a generic tablet, Metronidazole is also available as a branded tablet called Flagyl. There’s also a gel version called Zidoval. All three treatments have the same active ingredient: metronidazole.

Which version of Metronidazole should I use?

Answer:

When it comes to the tablets, there isn’t much difference between the generic tablets and the branded tablets. They may look different and come in different packaging, but the job they do and the way they work is the same.

Zidoval - the gel version of metronidazole - might be the best treatment option if your bacterial vaginosis is quite mild or if you don’t like taking tablets.

During your consultation with one of our clinicians you will be able to get expert advice on the right form and course of treatment to help you get rid of the infection quickly and effectively.

How effective is Metronidazole?

Answer:

Studies show that Metronidazole is highly effective at treating bacterial vaginosis. Ninety percent of women who take metronidazole find that it treats bacterial vaginosis within a week. It’s also 50% effective at stopping the infection from coming back for a year after treatment ends. ^[1]

Treated trusted sources:

Information, N.C. for B., Pike, U.S.N.L. of M. 8600 R., MD, B. and Usa, 20894 (2018). Which treatments are effective for bacterial vaginosis? www.ncbi.nlm.nih.gov. Institute for Quality and Efficiency in Health Care (IQWiG).