Phenytoin is available in Canada by prescription only.
Dilantin, Phenytoin Sodium and Tremytoine
How to Use
The actual dosage will vary until the doctor stabilizes the blood levels needed for maximum therapeutic dosage. Phenytoin is taken by mouth or administered by injection in the hospital.
- Common side effects of phenytoin may include slurred speech, dizziness, insomnia, coordination problems, constipation, nausea and vomiting.
- Use over a long period may also result in some connective tissue damage. Coarsening of facial features, overgrowth of the gums, and enlargement of the lips may occur.
- Seniors and those with impaired liver function should be under close medical supervision because the liver is to susceptible to phenytoin.
- People with diabetes should be cautious taking phenytoin because it may inhibit the release of insulin in the body.
- If a skin rash results when taking phenytoin, seek an alternate drug from your doctor immediately.
Do not stop taking phenytoin abruptly. This can precipitate status epilepticus.
If you are using any over-the-counter medication, inform doctor or pharmacist. Some medications may increase the phenytoin level in the blood. Others may decrease it. Mothers considering breastfeeding should consult their physician. Small amounts of phenytoin may be passed in human milk. Tip:Do not consume too much alcohol as it upsets the blood serum levels of phenytoin.
Substances that may increase the level of phenytoin in the bloodExpand Substances that may increase the level of phenytoin in the blood Section
- alcohol (acute intake)
- amphotericin B
- cimetidine (Tagamet)
- salicylates (ASA)
Substances that may decrease the level of phenytoin in the bloodExpand Substances that may decrease the level of phenytoin in the blood Section
- antacids containing calcium
- antibacterial agents/fluoroquinolones (ciprofloxacin, rifampin)
- alcohol (chronic abuse)
- folic acid
Substances that may either increase or decrease the level of phenytoin in the bloodExpand Substances that may either increase or decrease the level of phenytoin in the blood Section
- sodium valproate
- valproic acid
Phenytoin may decrease the effects of these substancesExpand Phenytoin may decrease the effects of these substances Section
- acetaminophen (Tylenol)
Phenytoin may either increase or decrease the level of these substancesExpand Phenytoin may either increase or decrease the level of these substances Section
- sodium valproate
- valproic acid
Phenytoin may affect the blood level and/or alter the effects of these substancesExpand Phenytoin may affect the blood level and/or alter the effects of these substances Section
- oral contraceptives
Take next dose as soon as you remember, then resume medication as usual. Do not double the dosage to catch up on therapeutic effect.
Store at room temperature between 15°C and 30°C. Keep away from children, heat, light and moisture.
- Capsules: 300 to 400 mg daily for adults, 4 to 8 mg/kg daily for children
- Tablets (flavoured, chewable): 30 mg for infants
DisclaimerExpand Disclaimer Section
The material offered at this site is to provide general information about epilepsy to the public. It is not intended to be taken as medical advice. Although all material presented at this site has been thoroughly researched and is believed to be correct, Epilepsy Ontario accepts no liability. Consult your physician and/or neurologist with any questions you have. People with epilepsy should never discontinue anti-epileptic medications or make changes in activities unless specifically advised to do so by an attending physician.