Drug interactions
Lamivudine + Sulfamethoxazole
Severity: Minor
Lamivudine and Sulfamethoxazole: 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
Trimethoprim-sulfamethoxazole increases lamivudine exposure modestly, an effect mainly due to trimethoprim. No lamivudine dose change is generally needed with normal renal function.
What this interaction means in plain words
Lamivudine and Sulfamethoxazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Reduced renal tubular secretion of lamivudine through competition at organic cation transporters, mainly by trimethoprim.
What to do
No dose adjustment is needed with normal renal function; monitor for lamivudine adverse effects, especially at high-dose cotrimoxazole or renal impairment.
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 Lamivudine
Frequently asked questions
Can I take Lamivudine with Sulfamethoxazole?
MediHelp rates the interaction as minor. Lamivudine and Sulfamethoxazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Trimethoprim-sulfamethoxazole increases lamivudine exposure modestly, an effect mainly due to trimethoprim. No lamivudine dose change is generally needed with normal renal function.
How serious is the interaction between Lamivudine and Sulfamethoxazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No dose adjustment is needed with normal renal function; monitor for lamivudine adverse effects, especially at high-dose cotrimoxazole or renal impairment.
What other medicines interact with Lamivudine?
MediHelp also lists interactions of Lamivudine with, for example, Elvitegravir / cobicistat / emtricitabine / tenofovir df, Atidarsagene autotemcel, Betibeglogene autotemcel. The full list is on the Lamivudine page.
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