Drug interactions
Gliclazide + Sulfamethoxazole
Severity: Major
Gliclazide and Sulfamethoxazole: major 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
Sulfamethoxazole, usually given as co-trimoxazole, can enhance the glucose-lowering effect of sulfonylureas and has been linked to serious hypoglycemia. Elderly patients and those with kidney disease are particularly vulnerable.
What this interaction means in plain words
Gliclazide and Sulfamethoxazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Sulfamethoxazole inhibits CYP2C9, which metabolizes the sulfonylurea, and may displace it from protein binding.
What to do
Monitor blood glucose closely, particularly in the first days of therapy, and lower the gliclazide dose if needed; consider an alternative antibiotic in high-risk patients.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Gliclazide
Frequently asked questions
Can I take Gliclazide with Sulfamethoxazole?
MediHelp rates the interaction as major. Gliclazide and Sulfamethoxazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Sulfamethoxazole, usually given as co-trimoxazole, can enhance the glucose-lowering effect of sulfonylureas and has been linked to serious hypoglycemia. Elderly patients and those with kidney disease are particularly vulnerable.
How serious is the interaction between Gliclazide and Sulfamethoxazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood glucose closely, particularly in the first days of therapy, and lower the gliclazide dose if needed; consider an alternative antibiotic in high-risk patients.
What other medicines interact with Gliclazide?
MediHelp also lists interactions of Gliclazide with, for example, Ciprofloxacin, Clarithromycin, Disopyramide. The full list is on the Gliclazide page.
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