Metronidazole

Metronidazole is an antibiotic.

It’s used in the treatment of conditions such as bacterial vaginosis and pelvic inflammatory disease.

Metronidazole is only available on prescription. Metronidazole is also used to treat various other infections.

The most common side effects of metronidazole tablets, liquid, suppositories or vaginal gel are feeling or being sick, diarrhoea, and a slight metallic taste in your mouth.

Do not drink alcohol while taking a course of metronidazole tablets, liquid, suppositories or vaginal gel, or for 2 days after finishing treatment. Alcohol can cause side effects such as feeling and being sick, stomach pain, hot flushes, a pounding heartbeat (palpitations) and a headache.

For most infections, you’ll start to feel better in a few days but for some it may take longer. When treating rosacea, you may only notice a difference after several weeks.

Metronidazole tablets or suppositories are called by the brand name Flagyl.

Metronidazole cream is called by the brand names Rosiced or Rozex. The gel is called by the brand names Acea, Anabact, Metrogel, Metrosa, Rozex or Zyomet.

Metronidazole can be taken by most adults and children. Metronidazole is not suitable for some people.

To make sure the tablets, liquid or suppositories are safe for you, tell your doctor if you:

• have had an allergic reaction to metronidazole or any other medicines in the past
• are pregnant or breastfeeding
• have liver problems
• are having dialysis
• feel you will not be able to stop drinking alcohol while using metronidazole

To make sure the external cream or gel is safe for you, tell your doctor if you:

• have had an allergic reaction to metronidazole or any other medicines (including any creams or ointments) in the past
• are pregnant or breastfeeding

To make sure the vaginal gel is safe for you, tell your doctor if you:

• have had an allergic reaction to metronidazole or any other medicines in the past
• are pregnant or breastfeeding
• have liver problems
• feel you will not be able to stop drinking alcohol while using metronidazole
• think you may have vaginal thrush

Pregnancy and breastfeeding

It’s generally safe to use metronidazole while you’re pregnant or breastfeeding.

If you’re breastfeeding, take care when applying metronidazole cream or gel. Make sure you do not accidentally get it on your breasts. If this happens, wash off any cream or gel from your breasts before feeding your baby.

For more information about how metronidazole can affect you and your baby during pregnancy, visit the Best Use of Medicines in Pregnancy (BUMPS) website.

Tell your doctor if you’re:

• trying to get pregnant
• pregnant
• breastfeeding

Cautions with other medicines

Metronidazole cream or gel is not known to cause any problems with other medicines. However, there are some medicines that don’t mix well with the tablets, suppositories, liquid or vaginal gel.

Tell your doctor before you start taking metronidazole tablets, suppositories, liquid or vaginal gel if you’re taking these medicines:

• a blood thinner called warfarin
• lithium (used to treat some types of mental health problem)
• disulfiram (used to help people stay off alcohol)
• phenytoin or phenobarbitone (used to treat epilepsy)
• ciclosporin (used to dampen the immune system)
• fluorouracil or busulfan (used to treat some types of cancer)
• any medicines that you take as a liquid, in case these contain alcohol

Mixing metronidazole with herbal remedies and supplements

There are no known problems with taking herbal remedies and supplements alongside metronidazole. However, some remedies and supplements that come as liquids that you drink may also contain alcohol. Check the list of ingredients or ask the supplier or manufacturer.

For the treatment of Bacterial Vaginosis, it is recommended you take one tablet twice a day for seven days.

How long should I take it for?

It’s very important to keep taking metronidazole for as long as your doctor has prescribed it.

What if I forget to take it?

If you forget to take a dose, take it as soon as you remember, unless it’s nearly time for your next dose. In this case, just leave out the missed dose and take your next dose as normal.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to remember your medicines.

What if I take too much?

Accidentally taking an extra dose of metronidazole is unlikely to harm you or your child.

Speak to your pharmacist or doctor if you’re worried or you take more than 1 extra dose.

Always complete your course, even if you start to feel better.

It’s unusual to have side effects when using metronidazole cream or gel. However there can be some common side effects with the tablets, suppositories or vaginal gel.

Do not drink alcohol while taking the tablets or liquid or using the vaginal gel or suppositories. It can give you severe side effects such as feeling or being sick, stomach pain, hot flushes, a pounding heartbeat (palpitations) and a headache. After finishing your treatment, wait for 2 days before drinking alcohol again. This allows the metronidazole to leave your body.

Common side effects

Keep taking the medicine, but talk to your doctor or pharmacist if these side effects bother you or do not go away:

• feeling sick (nausea)
• being sick (vomiting) or diarrhoea
• metallic taste in your mouth or a furry tongue

Serious side effects

Serious side effects are rare and happen in less than 1 in 1,000 people.

Call a doctor straight away if:

• you get yellow skin or the whites of your eyes turn yellow – these can be warning signs of liver or gallbladder problems
• you get unexpected infections, mouth ulcers, bruising, bleeding gums, or extreme tiredness – these can be caused by a blood problem
• you have bad stomach pains which may reach through to your back – this can be a sign of pancreatitis
• you have blurred or double vision
• you have a high temparture and stiff neck, you’re seeing or hearing things that are not there (hallucinating), feeling confused, unable to cope with bright light or having difficulty speaking – these can be warning signs of meningitis, or that metronidazole is affecting your brain

If you suspect that you or someone else are showing signs of meningitis, or other problems related to the brain, speak to a doctor or go to your A&E.

Serious allergic reaction

In rare cases, it’s possible to have a serious allergic reaction (anaphylaxis) to metronidazole.

Immediate action required:Call 999 or go to A&E now if:

• you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
• you’re wheezing
• you get tightness in the chest or throat
• you have trouble breathing or talking
• your mouth, face, lips, tongue or throat start swelling
• You could be having a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of metronidazole tablets, cream, gel, suppositories or vaginal gel. For a full list see the leaflet inside your medicines packet.

Information:

You can report any suspected side effect using the Yellow Card safety scheme.

How to cope with side effects

What to do about:

• feeling sick (nausea) – stick to simple meals and do not eat rich or spicy food. You should always try to take your metronidazole after a meal or snack.
• being sick (vomiting) or diarrhoea –drink lots of fluids, such as water or squash to avoid dehydration. Take small, frequent sips if you are being sick. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. If your diarrhoea and vomiting continues for more than 24 hours contact your doctor for advice. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor.
• metallic taste in your mouth or a furry tongue – drink plenty of water and eat plain foods that you usually enjoy. If your tongue is very furry, this could be a sign of thrush – ask your pharmacist or doctor for advice.

Metronidazole is an antibiotic. It works by stopping the growth of the bacteria (or parasites) causing the infection.

For most infections, you should feel better within a few days. With serious swelling (including dental infections), the medicine will start working within a few days but it may take longer before your symptoms start to get better.

For some of the infections that metronidazole is used for, you may only begin to notice an improvement after a week.

When using the cream or gel to treat rosacea, you may have to wait a few weeks before you see any improvement.

It’s very important that you keep taking metronidazole until the course is finished. Do this even if you feel better. It will help stop the infection coming back.

Tell your doctor if you still do not feel better 2 or 3 days after finishing your course of metronidazole. Also tell them if, at any time, you start to feel worse.

Metronidazole does not stop any type of contraception from working, including the combined pill and emergency contraception.

However, if metronidazole makes you vomit or have severe diarrhoea, your contraceptive pills may not protect you from pregnancy. If this happens, follow the instructions in the leaflet that comes with your contraceptive pills.

Some people get a fungal infection called thrush after taking a course of antibiotics like metronidazole. This is more common if you’re using the vaginal gel. It happens because antibiotics kill the normal harmless bacteria that help to protect you against thrush.

Ask your pharmacist or doctor for advice if this happens to you.

There’s no clear evidence to suggest that taking metronidazole will reduce fertility in either men or women. However, speak to a pharmacist or doctor before taking it if you’re trying to get pregnant.

Metronidazole does not usually affect you being able to drive or cycle.

However, very rarely, some people suffer from drowsiness or blurred vision. Do not drive or ride a bike until you stop feeling drowsy and your vision is clear.

Do not drink alcohol while you’re taking metronidazole, including for 2 days afterwards. This gives the medicine time to leave your body.

This is important because metronidazole can react with alcohol to cause a number of side effects. These include feeling and being sick, stomach pain, hot flushes, a pounding heartbeat (palpitations) and a headache.

You must not have any alcohol (in either your food or drink) while taking metronidazole – and for 2 days afterwards.

Otherwise you can eat and drink normally.