Drug interactions
Fosphenytoin + Upadacitinib
Severity: Major
Fosphenytoin and Upadacitinib: 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
Fosphenytoin is converted to phenytoin, which induces CYP3A4 and may reduce upadacitinib exposure. Efficacy may be lost.
What this interaction means in plain words
Fosphenytoin and Upadacitinib 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.
Fosphenytoin belongs to Central Nervous System; Upadacitinib belongs to Musculoskeletal.
Why it happens
Phenytoin induces CYP3A4 and increases upadacitinib clearance.
What to do
Avoid the combination if possible. If both are necessary, monitor disease activity closely.
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 Upadacitinib
- Abrocitinib + Upadacitinib Contraindicated
- Adenovirus types 4 and 7 live + Upadacitinib Contraindicated
- Baricitinib + Upadacitinib Contraindicated
- Bcg vaccine live + Upadacitinib Contraindicated
- Dengue vaccine + Upadacitinib Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Upadacitinib Contraindicated
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Upadacitinib?
MediHelp rates the interaction as major. Fosphenytoin and Upadacitinib 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. Fosphenytoin is converted to phenytoin, which induces CYP3A4 and may reduce upadacitinib exposure. Efficacy may be lost.
How serious is the interaction between Fosphenytoin and Upadacitinib?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If both are necessary, monitor disease activity closely.
What other medicines interact with Upadacitinib?
MediHelp also lists interactions of Upadacitinib with, for example, Abrocitinib, Adenovirus types 4 and 7 live, Baricitinib. The full list is on the Upadacitinib page.
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