Phenytoin
Also sold as: Epanutin, Dilantin
Prescription neededEpilepsy and nerve pain
Comes as:CapsuleTabletSuspensionInjection
Also sold as: Epanutin, Dilantin
Dose is set by your doctor, often 200 mg to 400 mg a day, sometimes guided by blood levels. Take it at the same time each day and do not stop it suddenly.
Your doctor may give you a different dose. Children's doses depend on weight.
Stop taking it and see a doctor straight away if you notice:
Medicines that can react with this one.
Phenytoin strongly lowers daclatasvir levels; do not combine.
Phenytoin makes the contraceptive pill less effective; use another method.
Isoniazid raises phenytoin levels and can cause toxicity.
Phenytoin makes levonorgestrel less effective; ask a doctor about a double dose or a copper IUD.
Phenytoin changes warfarin levels in both directions; INR must be checked closely.
Phenytoin lowers theophylline levels, and theophylline can lower phenytoin levels.
Raises phenytoin levels; watch for unsteadiness or drowsiness.
Phenytoin lowers clonazepam levels; seizure control should be watched.
Raises phenytoin levels; watch for unsteadiness or drowsiness.
High doses of pyridoxine can lower phenytoin levels.
Phenytoin lowers dexamethasone levels, and dexamethasone can change phenytoin levels.
Fluconazole raises phenytoin levels.
Fluoxetine can raise phenytoin levels and cause toxicity.
Folic acid can lower phenytoin levels and seizure control; the doctor may check levels.
Metronidazole can raise phenytoin levels.
Phenytoin strongly lowers quetiapine levels, so it may not work.
Phenytoin levels can change in either direction; levels should be checked.