Side effects to consider when taking Metronidazole

Metronidazole is an antibiotic used to treat infections. It stops certain bacteria and parasites from growing. It does not work for viral infections (such as the common cold and the flu). It can also be used with other medicines to treat some stomach ulcers.

What to consider when taking Metronidazole tablets

Before taking Metronidazole, consult your doctor or pharmacist know if you are allergic to similar medicines. Tell them about any other allergies as well.

You should also tell your doctor if you have any other conditions. In particular, tell them if you have a history of:

• Liver disease

• Kidney disease

• Allergic reactions

• Certain blood disorders (such as a low blood cell count)

• Rare genetic disorders (such as Cockayne syndrome)

Do not drink alcohol while taking metronidazole. Do not consume products containing propylene glycol (E1520). Do not consume either of these for at least three days after finishing the course.

Consuming propylene glycol when on metronidazole can cause:

• Severe stomach upset or cramps

• Nausea and  vomiting

• Headaches

• Flushes

Metronidazole may make you feel dizzy. As well as alcohol, do not consume marijuana (cannabis), as it can make this worse. You may also not be as alert as usual. For this reason, do not drive, use machinery or take part in anything that needs complete focus.

If you are getting vaccinated, tell your provider that you are on metronidazole. This is because it can make some live vaccines (such as the typhoid vaccine) less effective.

Common side effects of metronidazole tablets

Metronidazole has some side effects. They should stop after a few days. If they don’t, tell your GP.

When you first take the medicine, you may experience:

• Nausea

• Vomiting

• Diarrhoea

• A feeling of agitation

• Back pain

• Temporary blindness

• Decreased or blurred vision

Other side effects include:

• Burning

• Numbness

• Tingling or pain in the hands or feet

• Abrupt changes in speech patterns

• States of panic or depression

• Dizziness

• Drowsiness

• Eye pain

• High fever

• Headache or migraine

• Lack of coordination

• Hallucinations

• Seizures

• Shakiness

• Unsteadiness when walking

• Slurred speech or speaking difficulty

• Stiffness in the back or neck

• Unusual fatigue

Sometimes, other side effects can occur. These should go away without treatment. Tell your GP if you still have them after several days or if you are worried.

These side effects can include:

• Feeling light-headed

• Feeling that you or your surroundings are constantly moving

• Heartburn

• A sensation of spinning or vertigo

• Stomach cramps

• Trouble sleeping or insomnia

• Sudden change in weight

• Black solid stools

• Blood in urine

• Body aches or pain

• Burning sensation while urinating

• Chills or goosebumps

• Difficulty with breathing or asthma

• Ear congestion

• Fainting spells

• Pelvic pressure

• Irregular heartbeat

• Voice loss

• Nasal congestion

• Red spots on the skin

• Runny nose

• Skin rashes, hives, redness or itching

• Frequent sneezing

• Unusual bleeding or bruising

• Vaginal irritation, discharge or dryness that started after taking the medicine

Serious side effects of Metronidazole

In some cases, severe side effects occur. Get immediate medical help if any of these occur:

• Change in taste

• Congestion (ears or nose)

• Dry mouth

• Pain around the eyes and cheekbones

• Tenderness or swollen glands in the neck

• Trouble swallowing

• Unpleasant or sharp metallic taste in the mouth

• Unusual voice changes

• Decreased interest in sexual intercourse

• Inability to have or keep an erection

• Loss in sexual ability, desire, drive or performance

• Painful sexual intercourse