About Phenytoin 100 mg Tablet
Phenytoin 100 mg Tablet contains Phenytoin 100 mg. Phenytoin is an anti-epileptic medicine used to prevent and control seizures. It is taken regularly, and the dose is adjusted using blood tests because the right amount differs from person to person. It should not be stopped suddenly.
Uses of Phenytoin 100 mg Tablet
- Epilepsy — tonic-clonic (grand mal) and focal seizures
- Prevention of seizures during or after brain surgery or head injury, as advised by your doctor
Benefits
In epilepsy
Taken regularly, it helps reduce the number of seizures, which can make daily life safer. It does not work for absence (petit mal) seizures.
Side effects
Do not stop taking it suddenly, as seizures can return or become severe. People of some Asian backgrounds may have a higher risk of serious skin reactions.
Common
- Swollen or overgrown gums
- Dizziness or unsteadiness
- Drowsiness
- Nausea or constipation
- Extra hair growth
- Coarsening of facial features with long use
Get medical help if you notice
- Skin rash, especially with fever, blisters, peeling or mouth sores — stop and contact your doctor straight away
- Fever, swollen glands and feeling very unwell — seek medical help
- Unsteady walking, double vision, slurred speech, jerky eye movements or confusion (signs of too much medicine) — contact your doctor
- Yellow eyes or skin, dark urine — contact your doctor
- Sore throat, fever, bruising or bleeding — contact your doctor
- Thoughts of harming yourself, or new or worse depression — contact your doctor straight away
How to use
Take it exactly as your doctor prescribed, at the same times each day. Swallow the tablet with water. Do not switch brands or forms without your doctor's advice, as the amount absorbed can differ.
How it works
It slows down the repeated firing of nerve cells in the brain by blocking sodium channels, which helps stop seizures from starting and spreading.
Safety advice
Alcohol Unsafe
Avoid alcohol. It can change phenytoin levels and increase the risk of seizures and side effects.
Pregnancy Consult your doctor
It can increase the risk of birth defects. Do not stop it on your own, as seizures in pregnancy are also dangerous. Talk to your doctor before planning a pregnancy.
Breastfeeding Consult your doctor
Small amounts pass into breast milk. Ask your doctor before breastfeeding.
Driving Caution
It can cause dizziness and drowsiness. Follow your doctor's advice and the driving rules for people with epilepsy.
Kidney Caution
Tell your doctor if you have kidney disease; blood level tests may need careful reading.
Liver Caution
It is processed by the liver. Your doctor may lower the dose and check blood levels more often.
If you miss a dose
If you miss a dose, take it when you remember. If it is nearly time for the next dose, skip the missed one. Do not take two doses together. Tell your doctor if you miss several doses.
Quick tips
- Do not stop it suddenly.
- Brush and floss well and see a dentist regularly to reduce gum problems.
- Go for blood tests as advised to check the level of the medicine.
- It can make hormonal contraceptives less effective — ask your doctor about contraception.
- Keep antacids at least 2 hours apart from your dose.
Substitutes
Same salts in the same strength from other makers. Only switch brands on your doctor's or pharmacist's advice; our pharmacist checks every order against the prescription.
Fact box
- Chemical class
- Hydantoin
- Therapeutic class
- Neurology / anti-epileptic
- Action class
- Anticonvulsant (sodium channel blocker)
- Habit forming
- No
- Prescription
- Required
Interactions with other medicines
Tell your doctor and pharmacist about every medicine, vitamin and herbal product you take.
| Medicine | What can happen |
|---|---|
| Hormonal contraceptives | Phenytoin can make them less effective |
| Blood thinners such as warfarin | Effects of both medicines can change; extra blood tests are needed |
| Isoniazid, fluconazole and some other medicines | Can raise phenytoin levels and cause toxicity |
| Rifampicin and carbamazepine | Can lower phenytoin levels |
| Antacids and calcium | Reduce phenytoin absorption; keep them apart |
This page is general information to help you understand your medicine. It is not a substitute for advice from your doctor or pharmacist. Do not start, stop or change a medicine on your own.
Written by the Asthra Health Care team from the approved prescribing information (Phenytoin prescribing information (CDSCO-approved labelling); US FDA phenytoin labelling; NICE BNF: phenytoin). Pharmacist review pending.