Drug interactions
Clarithromycin + Trimethoprim
Severity: Minor
Clarithromycin and Trimethoprim: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Both drugs have been linked to QT prolongation, and trimethoprim can raise potassium. The combination may modestly increase arrhythmia risk, mainly in patients with other risk factors.
What this interaction means in plain words
Clarithromycin and Trimethoprim have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Clarithromycin belongs to Anti Bacterial; Trimethoprim belongs to Anti Bacterial.
Why it happens
Possible additive QT prolongation, with hyperkalemia from trimethoprim as an added contributor.
What to do
Check ECG and electrolytes including potassium in high-risk patients such as those with renal impairment or heart disease. No action is usually needed otherwise.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
Other interactions of Trimethoprim
Frequently asked questions
Can I take Clarithromycin with Trimethoprim?
MediHelp rates the interaction as minor. Clarithromycin and Trimethoprim have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Both drugs have been linked to QT prolongation, and trimethoprim can raise potassium. The combination may modestly increase arrhythmia risk, mainly in patients with other risk factors.
How serious is the interaction between Clarithromycin and Trimethoprim?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check ECG and electrolytes including potassium in high-risk patients such as those with renal impairment or heart disease. No action is usually needed otherwise.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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