Anticonvulsant (Anti-seizure medicine)
Last reviewed June 2026
Who is this for?
Phenytoin Sodium is a medicine that calms down excessive electrical activity in the brain to prevent seizures (convulsions). It works by stabilizing nerve cells so they don't fire too rapidly.
Inhibits neuronal sodium channels by stabilizing their inactive state, reducing repetitive neuronal firing and preventing the spread of seizure activity across the brain. Also increases the threshold for seizure generation by enhancing GABAergic inhibitory neurotransmission.
Prescription Required
You need a doctor's prescription to buy this drug.
Explore this drug
Adults usually start with 100mg taken 3 times a day, or 300mg once daily. Swallow the capsule whole with a full glass of water — do not crush or chew it. You can take it with food to reduce stomach upset. Your doctor will adjust your dose based on how your body responds, so follow their instructions carefully. In Nigeria, you may find it sold as Festphenytoin Capsules.
Take the missed dose as soon as you remember. But if it is almost time for your next dose, skip the missed one and continue your normal schedule. Never take a double dose to make up for the one you missed. Missing doses can trigger seizures, so try to take it at the same time every day.
Do not buy phenytoin from roadside sellers or unregistered pharmacies — fake or expired medicines are dangerous, especially for seizure control. Do not stop taking this medicine suddenly without your doctor's advice, as this can cause very serious, life-threatening seizures. This is a prescription medicine — do not share it with others even if they also have convulsions, because the dose must be carefully adjusted for each person.
Alcohol makes the side effects of phenytoin much worse — avoid drinking beer, palm wine, ogogoro, or any alcohol while on this medicine. Antacids (like aluminum or magnesium-based ones for stomach acid) can reduce how well phenytoin works — take them at least 2 hours apart. Some antibiotics and antifungal medicines can change phenytoin levels in your blood, so always tell your doctor or pharmacist about every medicine you are taking.
Check your specific combination
Is it safe to take Phenytoin with your other drugs?
Phenytoin is NOT safe during pregnancy as it can cause serious birth defects; if you are pregnant, planning to become pregnant, or breastfeeding, talk to your doctor immediately about safer alternatives.
Store in a cool, dry place away from direct sunlight and heat — Nigerian weather can be very hot, so avoid leaving it in your car or near a window. Keep the container tightly closed to protect from moisture. Always keep out of reach of children.
For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.
Names this drug is sold under — especially in Nigerian and West African pharmacies
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Counterfeit Drug Warning
Fake drugs are a serious problem in Nigeria. Always buy from a registered pharmacy. If the packaging looks different from what is described above, do not use it.