The Independent Pharmacy

What Is Metronidazole?

Andy Boysan
Andy BoysanBPharmDirector & Superintendent Pharmacist

Reviewed on 8 Nov 2023

Although it may feel embarrassing if you think you may have Bacterial Vaginosis (also known as BV), it is a very common condition that affects a lot of women — and it’s easy to find and buy an effective treatment like Metronidazole discreetly online. But if you’ve never heard of it, you might be wondering, ‘What is Metronidazole?’

In the guide below, we will be covering everything you need to know about Metronidazole, from Metronidazole uses to dosage, to how quickly Metronidazole takes to work. Read on for more information about the popular BV treatment.

Metronidazole 400mg Tablets
Metronidazole 400mg Tablets
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What is Metronidazole?

Metronidazole (also spelt Metronidazole) is a type of antibiotic medication that is used to treat several different infections and it is commonly used to treat bacterial vaginosis (BV). It usually comes in the form of 400mg tablets, but can also come as a gel, cream, liquid, or suppository.

Metronidazole is a very effective and fast-acting treatment, which is why it is one of the most popular medicines used to treat BV and other infections.

The treatment is only available with a prescription in the UK from your doctor or a registered online pharmacy. (You can buy Metronidazole discreetly from The Independent Pharmacy here following a short online consultation.)

You can find out more about the various bacterial vaginosis treatments here.

What is Metronidazole used for?

Metronidazole is used to treat a range of different bacterial and parasitic infections (as well as some other conditions).

These conditions include bacterial vaginosis (BV), pelvic inflammatory disease, skin infections, rosacea and mouth infections (such as infected gums and dental abscesses).

Metronidazole can also be used to treat skin ulcers, bedsores and wounds, and infected insect bites. It may also be used in conjunction with other medications to treat a specific type of stomach or intestinal ulcer caused by bacteria.

This antibiotic only treats certain bacterial and parasitic infections; it will not work for viral infections like the common cold or flu.

How does Metronidazole work?

Metronidazole is an antibiotic that works by stopping the growth of certain bacteria and parasites which are causing the infection.

Here at The Independent Pharmacy, we supply Metronidazole to treat bacterial vaginosis (BV). Bacterial vaginosis is a common condition which is thought to be caused by a change in the natural balance of bacteria that live in the vagina.

The vagina is naturally a slightly acidic environment, due to a bacteria called lactobacilli which produces lactic acid. The resulting acidity prevents other bacteria from growing inside the vagina and maintains a healthy environment.

When the natural balance of this bacteria is disrupted (which could be due to all sorts of different factors), the number of lactobacilli decreases, which means the vagina isn’t acidic enough to prevent other bacteria from growing; this imbalance of bacteria is what causes BV.

Metronidazole helps to kill some of the excess bacteria that occur in BV and returns the balance of bacteria to normal.

Metronidazole tablets, liquid or suppositories

Metronidazole can come in a few different forms.

The most popular is the 400mg oral tablet, which is the only oral option for treating bacterial vaginosis. We offer the Metronidazole 400mg dosage here at The Independent Pharmacy — you can buy it here.

There are other forms of Metronidazole available; this medication can also come as a gel, cream, liquid, or suppository.

Zidoval is a vaginal gel that contains metronidazole. The gel treats the BV infection locally by being inserted into the vagina. It is a prescription-only treatment that can be purchased after a short online consultation.

If you are prescribed a liquid medicine form of Metronidazole by your GP, it will come with a plastic spoon or cup to help you measure out the correct dose before you drink it.

Alternatively, your doctor may prescribe suppositories if you have difficulty swallowing medicines. Your doctor will give you instructions on how to use it, or you can follow the directions that come in the medicine packaging.

Metronidazole ingredients

The active ingredient in this medication is metronidazole 400mg.

The other ingredients are: Croscarmellose Sodium, Cellulose, Colloidal Silica, Lactose, Magnesium Stearate, Maize Starch, Polyethylene Glycol, Titanium Dioxide (E171), Hydroxypropylcellulose (E463), and Methylhydroxypropylcellulose (E464).

Please note that the above ingredients are representative of metronidazole 400mg tablets produced by one manufacturer. Different pharmaceutical manufacturers may use different inactive ingredients.

Who can take Metronidazole?

Metronidazole can be taken by most adults without any problems or negative side effects. However, Metronidazole isn't suitable for some people.

To make sure Metronidazole is safe for you to use, you should tell your doctor if you:

  • Are pregnant (read our guide on using Metronidazole while pregnant here)
  • Are breastfeeding
  • Have liver problems
  • Are having dialysis
  • Have had an allergic reaction to metronidazole or any other medicines in the past
  • Feel you won't be able to stop drinking alcohol while using metronidazole (the interaction can be very unpleasant — read our guide on Metronidazole and alcohol to find out more)

This applies regardless of whether you are using the tablet, gel, liquid or suppository form of Metronidazole.

Occasionally, your doctor may prescribe or suggest a different antibiotic which may be more suitable for you (such as if you are allergic or have previously had a bad reaction to Metronidazole in the past). If this is the case, Clindamycin cream is usually used as an alternative treatment for bacterial vaginosis.

Does Metronidazole work?

Metronidazole works very well to treat a range of different bacterial and parasitic infections such as BV, and is extremely effective.

But how quickly does Metronidazole work? Well, a treatment course of Metronidazole 400mg tablets for BV generally lasts for seven days (in which you have to take one 400g tablet twice daily for seven days). You may start to see improvements within a few days of taking the antibiotic, but it is important to complete the course of treatment — failure to do so may result in the infection coming back.

The alternative is to take a Metronidazole cream or gel (like Zidoval). This is also an effective treatment for BV that is applied inside the vagina at bedtime for five days. Again, it is important to complete the course of treatment.

Both have similar results, though it’s thought that the vaginal treatment may cause fewer side effects (but it can be less desirable to use than tablets).

What are the side effects of using Metronidazole?

Metronidazole is a commonly-used medicine and most people have no problems taking it for a week course.

Although unusual, Metronidazole tablets can have some side effects. The most common may include headaches, vomiting, diarrhoea, heartburn, constipation, loss of appetite, abdominal cramps, and a metallic taste in the mouth. You can find out more on our Metronidazole side effects page.

Metronidazole dosage

Metronidazole is available in several different doses. The dosage is based on your medical condition and your response to the treatment.

Here at The Independent Pharmacy, we offer the Metronidazole 400mg dosage tablets. This is the recommended dosage used to treat BV, and is normally taken in 400mg tablets twice a day, for a seven-day course (bringing the dosage to 800mg daily in divided doses).

Do not take this medicine in larger or smaller doses than your doctor or the directions on your prescription label suggest. You should also avoid taking Metronidazole for longer than recommended.

Taking Metronidazole with other medicines

Generally speaking, Metronidazole isn't known to cause any problems when taken alongside most other medicines. However, there are some medicines that don't mix well with Metronidazole (whether it is the tablet form, liquid, gel or suppositories).

You should avoid taking Metronidazole if you use any of the following medications:

  • Anti-coagulants (blood thinning agents), such as warfarin
  • Lithium (if taken at the same time as metronidazole, the kidneys may be affected)
  • Phenytoin, primidone or phenobarbitone (medicines used to treat epilepsy)
  • 5-fluorouracil or busulfan (used to treat some cancers)
  • Disulfiram (for alcohol abuse)
  • Cimetidine (for indigestion and heartburn)
  • Ciclosporin (used to reduce activity in the immune system)

You always seek advice from your doctor if you are currently taking any of the above medicines and wish to start a course of Metronidazole.

You should also avoid taking Metronidazole alongside any medicines which may contain alcohol — even in very small quantities — such as cough syrups and mouthwash. This is because Metronidazole is known to react badly with alcohol and may cause several unpleasant side effects; for more information, go to our Metronidazole and alcohol page.

Taking Metronidazole with paracetamol and ibuprofen

It is completely safe to take Metronidazole with painkillers such as paracetamol and ibuprofen; doing so will not result in any bad reactions.

If you're worried about a possible interaction, you can talk to your doctor or pharmacist, or check your medication leaflet.

Metronidazole and sex

It is advised to avoid sex until you have finished your course of treatment and your infection has completely cleared up.

This is because having sex may upset the pH balance in the vagina and make symptoms worse during treatment, as well as reducing the effectiveness of the medication.

BV may also be transferred between female sex partners, so it is best to avoid sex while you are treating BV. If your sexual partner is male, they cannot ‘catch’ BV, but they may carry the bacteria in their penis, which means you could become reinfected if you continue to have sex.

Can Metronidazole cause thrush?

Metronidazole does not directly cause thrush, however, some women can find that a course of oral antibiotics can lead to thrush.

Thrush is a yeast infection caused by the candida fungus and is different from bacterial vaginosis. Different vaginal infections have their individual specific treatments.

You can suffer from BV and a yeast infection at the same time. However, you should consult a doctor to be sure — they will be able to help you further. Alternatively, you can contact us for free impartial advice if you suspect you have more than one infection.

Metronidazole and the pill

Previously, it was thought that taking a course of Metronidazole may alter the effectiveness of your contraceptive pill. However, it has now been shown that Metronidazole does not affect the contraceptive pill.

For information read our ‘Metronidazole while pregnant’ guide.


Metronidazole is a safe and effective antibiotic medication used to treat bacterial vaginosis (BV), as well as other bacterial infections.

You can buy Metronidazole at The Independent Pharmacy. All you need to do is fill in a short online questionnaire — it’s quick and free to do. We offer a fast, secure and discreet online service and delivery straight to your door so that you can start treatment without delay.

For more information on BV, visit our bacterial vaginosis treatments page.


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