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Dental abscess - Management
What are the general issues when prescribing metronidazole?

  • Common adverse effects include a metallic taste and gastrointestinal irritation (in particular nausea and vomiting). These are more common at higher doses.
    • Advise that metronidazole should be taken with or after food.
  • Drug interactions:
    • Alcohol: some people taking oral metronidazole experience disulfiram-like reactions to alcohol (flushing, increased respiratory rate, increased pulse rate). Although there is no conclusive evidence to support an interaction between metronidazole and alcohol, people taking metronidazole should be advised of the possible consequences of drinking alcohol [Baxter, 2006].
    • Anticoagulants: the anticoagulant effects of warfarin can be markedly increased by metronidazole [ABPI Medicines Compendium, 2008; Baxter, 2006].
      • If concurrent use cannot be avoided, consider reducing the warfarin dosage appropriately (by between one-third to one-half) [Baxter, 2006].
      • Warn the individual of the possible risk of increased bruising and bleeding. Advise when to seek medical help.
    • Contraceptives: broad spectrum antibiotics may cause combined hormonal contraceptives to fail during the first 3 weeks of antibiotic treatment (see the CKS topic on Contraception for information on the pill or the patch) [FFPRHC, 2004; FFPRHC, 2005; FFPRHC, 2007].
      • Advise women to use an additional method of contraception during the course of antibiotic treatment and for 7 days afterwards. If this 7-day period runs beyond the end of the pack of contraceptive pills or patch, advise the woman to start a new pack without a break (omitting any inactive tablets).

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