Drug Interactions Table

This information on drug interactions with antimicrobials is intended for use as a guide and not as a complete reference source. Further information is available in the BNF Appendix 1 and in the SmPCs of the individual medicines (section 4.5) available at www.HPRA.ie. Please be aware that new evidence may emerge that may overtake some of these recommendations. This table lists antimicrobials according to the frequency of use in primary care.

Prescribers should be aware of the main serious drug interactions for regularly prescribed antibiotics.

GPs, dentists and other community prescribers may be less familiar with some less commonly prescribed agents which may be initiated in hospital or OPAT and have the potential for serious interactions with other medicines.

If a patient is prescribed an antibiotic or antifungal that you are not familiar with be alert for potential for drug interactions especially with concomitant use of statins, warfarin and non-vitamin K oral anticoagulants and antidepressants.

See also our pages on:

Drug Interactions Table (Click on the thumbnail image below for the full PDF)

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* Patient may be on via OPAT outpatient parenteral antimicrobial therapy

** Non-drug risk factors for prolonged QT interval: Family history, Increasing age, female sex, electrolyte abnormalities (hypokalaemia, hypocalcaemia, hypomagnesaemia), cardiac ischaemia, cardiomyopathies, hypothyroidism and hypoglycaemia.

*** Serotonergic Drugs: Triptans (e.g. sumatriptan); antidepressants; antipsychotics; anticonvulsants; antiparkinsonian agents; analgesics (e.g., fentanyl, pethidine, tramadol); cough and cold medication containing dextromethorphan; herbal products (St. John's Wort)

This is not a complete list; please consult with product SmPCs for further information.

Symptoms of Serotonin Syndrome

Alteration of mental status: agitation, confusion, delirium, hallucinations, drowsiness, coma.Neuromuscular hyperactivity: profound shivering, tremor, teeth grinding, myoclonus, ocular clonus, spontaneous clonus, hyperreflexia. Autonomic instability dilated pupils, diarrhoea, profuse sweating, flushing, tachycardia, hyper/hypotension.

In severe cases, hyperthermia, rhabdomyolysis, renal failure, and disseminated intravascular coagulopathy may develop

Combined Hormonal Contraception

Extra precautions are no longer required when using combined hormonal contraception (CHC) with antibiotics. (Unless those antibiotics are enzyme inducers e.g. rifampicin, rifabutin, isoniazid). The usual additional precautions regarding vomiting, diarrhoea and non-adherence to CHC apply. Correct contraceptive practice must be adhered to.

Reviewed November 2018

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