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Dyspepsia - unidentified cause - Management
What issues should I consider before prescribing metronidazole?
- Common adverse effects include a metallic taste and gastrointestinal irritation (in particular nausea and vomiting). These are more common at higher doses.
- 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: metronidazole can markedly increase the anticoagulant effects of warfarin [ABPI Medicines Compendium, 2008; Baxter, 2006]. If concurrent use cannot be avoided, monitor the international normalized ratio and adjust the warfarin dose accordingly [Baxter, 2006].
- Contraceptives: antibiotics may cause the combined oral contraceptive pill or patch to fail during the first few weeks of treatment [Baxter, 2006] (see the CKS topic on Contraception for information on the combined oral contraceptive pill or patch).
- Advise women to use additional contraception during the course of treatment and for 7 days afterwards. If this 7-day period runs beyond the end of the pack of contraceptive pills, advise the woman to start a new pack without a break (omitting any inactive tablets) [FFPRHC, 2005; FFPRHC, 2007].
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