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Dyspepsia - unidentified cause - Management
What issues should I consider before prescribing amoxicillin?
- Amoxicillin should not be taken by people who have true penicillin allergy. However, gastrointestinal adverse effects alone (e.g. nausea, vomiting, or diarrhoea) do not constitute an allergy to penicillin [BNF 55, 2008]:
- An erythematous, maculopapular rash is common with amoxicillin, but this only indicates hypersensitivity to amoxicillin and not usually to other penicillins [Sweetman, 2005].
- Note: an urticarial rash does constitute true penicillin allergy.
- Drug interactions:
- 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].
- Anticoagulants: documented reports of oral anticoagulant/penicillin (including amoxicillin) interaction are relatively rare [Baxter, 2006]. However, the British National Formulary advises that common experience in anticoagulant clinics is that a course of broad-spectrum antibiotic can alter the international normalized ratio [BNF 55, 2008].
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