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Sore throat - acute - Management
What are the general issues when prescribing phenoxymethylpenicillin?
- Phenoxymethylpenicillin (penicillin V) is a narrow-spectrum antibiotic and is usually well tolerated, but nausea, vomiting, or diarrhoea can sometimes occur.
- Phenoxymethylpenicillin should not be taken by people who have true penicillin allergy. However, gastrointestinal adverse effects alone (i.e. nausea, vomiting, or diarrhoea) do not constitute an allergy to penicillin [BNF 54, 2007].
- Drug interactions:
- Contraceptives: antibiotics may cause combined hormonal contraceptives (see the pill or the patch in the CKS topic on Contraception) to fail during the first 3 weeks of antibiotic treatment [FFPRHC, 2004; FFPRHC, 2005; FFPRHC, 2007].
- Advise the woman 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).
- 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 the International Normalization Ratio (INR) can be altered by a course of broad-spectrum penicillin [BNF 54, 2007].
- Warn the individual of the possible risk of increased bruising and bleeding. Advise when to seek medical help.
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