Talk to your doctor, pharmacist before being given metronidazole if you have:
- severe liver damage
- a blood formation disorder or
- a disease of brain, spinal cord or nerves
Therefore, your doctor will very carefully determine whether you should be treated with metronidazole.
If convulsive fits or any other nerve affections (e.g. numbness in limbs) become apparent during therapy, your treatment will promptly be revised.
Treatment must be stopped or revised immediately if you get severe diarrhoea which may be due to a severe large bowel disease called “pseudomembranous colitis” (see also section 4.)
As prolonged use of metronidazole may impair blood formation (see section “Possible side effects”), your blood counts will be monitored during treatment.
If you received this medicine your urine may be darkened.
Cases of severe liver toxicity/acute liver failure, including cases with a fatal outcome, in patients with Cockayne syndrome have been reported with products containing metronidazole.
If you are affected by Cockayne syndrome, your doctor should also monitor your liver function frequently while you are being treated with metronidazole and afterwards.
Tell your doctor immediately and stop taking metronidazole if you develop:
- stomach pain, anorexia, nausea, vomiting, fever, malaise, fatigue. Jaundice, dark urine, putty or mastic coloured stools or itching.
Treatment with Metronidazole should not usually be continued for longer than 10 days; the treatment period will only be extended in exceptional circumstances and if absolutely necessary. Repeat therapy with metronidazole will be restricted to cases where this is absolutely necessary. In such a case, you will be monitored particularly carefully.
Certain medicines are known to change the normal effect of this infusion.
Certain medicines can have their effect changed by this infusion.
These medicines should not be used at the same time as Metronidazole 500 mg/100 ml Solution for infusion.
Please tell your doctor if you are taking, have recently taken or might take any of the following medicines:
Amiodarone (used to treat irregular heartbeat)
When you receive this medicine, your heart function should be monitored. You should see your doctor if you notice any heart function abnormalities, dizziness or fainting.
Barbiturates (the active substance in sleeping pills)
The duration of action of metronidazole is reduced by phenobarbital; your metronidazole dose may therefore have to be increased.
Birth control pills
Your birth control pill may be less reliable while you are being given metronidazole.
Busulfan
Metronidazole should not be given to patients receiving busulfan because in that case toxic effects are more likely to occur.
Carbamazepine (a drug for the treatment of epilepsy)
This combination also warrants caution because metronidazole may increase the duration of action of carbamazepine.
Cimetidine (a drug for the treatment of stomach disorders)
Cimetidine may reduce the elimination of metronidazole in isolated cases and subsequently leads to increased serum metronidazole concentrations.
Coumarin derivatives (drugs that inhibit blood clotting)
Metronidazole may enhance the blood clotting inhibition brought about by coumarins. So, if you are taking a medicine that inhibits blood clotting (for example warfarin), you may need less of it during treatment with metronidazole.
Cyclosporin (a drug used to suppress undesirable immune responses)
When cyclosporin is given together with metronidazole, the blood levels of cyclosporin may increase; your doctor will therefore have to adjust your cyclosporin dose as appropriate.
Disulfiram (used in alcohol withdrawal therapy)
If you are taking disulfiram, you must not be given metronidazole, or disulfiram must be stopped.
Combined use of these two drugs may lead to states of confusion up to the point of a serious mental disorder (psychosis).
Drugs containing alcohol
Please refer to section ‘Using Metronidazole’ with food and drink.
Fluorouracil (an anticancer drug)
The daily dose of Fluorouracil may have to be reduced when giving it together with Metronidazole because metronidazole may lead to an increase of the blood level of Fluorouracil.
Lithium (used to treat mental illness)
Treatment with lithium preparations requires particularly careful monitoring during treatment with metronidazole, and the dose of the lithium preparation may need to be re-adjusted. Lithium treatment should be tapered or withdrawn before administration of metronidazole.
Mycophenolate mofetil (used for the prevention of rejection reactions after organ transplant).
Its effect may be weakened by metronidazole, so careful monitoring of the effect of the medicine is recommended.
Phenytoin (a drug for the treatment of epilepsy)
If you are taking phenytoin, your doctor will treat you with metronidazole only with caution because metronidazole may increase the duration of action of phenytoin. On the other hand, phenytoin may reduce the effect of metronidazole.
Tacrolimus (used to suppress unwanted immune reactions)
The blood levels of this agent and your kidney function should be checked when starting and stopping treatment with metronidazole.
Please tell your doctor if you are taking or have recently taken any other medicines, including medicines obtained without a prescription.