Drug interactions
Guselkumab + Phenytoin
Severity: Minor
Guselkumab 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
Guselkumab may reverse cytokine-mediated suppression of CYP450 enzymes in inflammatory disease, possibly altering clearance of CYP substrates. Clinical relevance for phenytoin is uncertain but possible given its narrow therapeutic index.
What this interaction means in plain words
Guselkumab 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.
Guselkumab belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Normalization of CYP expression as inflammation resolves may change phenytoin metabolism.
What to do
Check phenytoin levels when guselkumab is started or stopped and adjust the dose if levels change.
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 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
Other interactions of Guselkumab
- Adenovirus types 4 and 7 live + Guselkumab Major
- Bcg vaccine live + Guselkumab Major
- Guselkumab + Influenza virus vaccine quadrivalent intranasal Major
- Guselkumab + Measles mumps and rubella vaccine live Major
- Guselkumab + Measles mumps rubella and varicella vaccine live Major
- Guselkumab + Measles vaccine Major
Frequently asked questions
Can I take Guselkumab with Phenytoin?
MediHelp rates the interaction as minor. Guselkumab 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. Guselkumab may reverse cytokine-mediated suppression of CYP450 enzymes in inflammatory disease, possibly altering clearance of CYP substrates. Clinical relevance for phenytoin is uncertain but possible given its narrow therapeutic index.
How serious is the interaction between Guselkumab 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: Check phenytoin levels when guselkumab is started or stopped and adjust the dose if levels change.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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