Drug interactions
Dexamethasone-tobramycin + Phenytoin
Severity: Minor
Dexamethasone-tobramycin and Phenytoin: 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
Phenytoin strongly induces CYP3A4 and can substantially lower systemic dexamethasone exposure, reducing steroid effect. With topical dexamethasone-tobramycin this is unlikely to matter clinically.
What this interaction means in plain words
Dexamethasone-tobramycin and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Dexamethasone-tobramycin belongs to Anti Bacterial; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induction of CYP3A4 increases dexamethasone metabolism.
What to do
No change is needed for topical use. With systemic dexamethasone, monitor clinical response and increase the dose if needed.
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 Dexamethasone-tobramycin
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Dexamethasone-tobramycin with Phenytoin?
MediHelp rates the interaction as minor. Dexamethasone-tobramycin and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenytoin strongly induces CYP3A4 and can substantially lower systemic dexamethasone exposure, reducing steroid effect. With topical dexamethasone-tobramycin this is unlikely to matter clinically.
How serious is the interaction between Dexamethasone-tobramycin and Phenytoin?
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 change is needed for topical use. With systemic dexamethasone, monitor clinical response and increase the dose if needed.
What other medicines interact with Dexamethasone-tobramycin?
MediHelp also lists interactions of Dexamethasone-tobramycin with, for example, Capreomycin, Carboplatin, Ciprofloxacin. The full list is on the Dexamethasone-tobramycin page.
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