How Phenytoin works

Phenytoin is an antiepileptic medication. It controls seizures or fits by decreasing the abnormal and excessive activity of the nerve cells in the brain.

Side Effects

Nystagmus (involuntary eye movement), Double vision, Sleepiness, Anemia, Peripheral neuropathy (tingling and numbness of feet and hand), Gingival hyperplasia, Increased hair growth, Osteoporosis

Usage

Phenytoin is used in the treatment of seizures and trigeminal neuralgia.

Frequently Asked Questions

Q. How does Phenytoin work?

Phenytoin is used to control seizures (fits) in epilepsy patients and it works by suppressing the abnormal and excessive activity of the nerve cells in the brain.

Q. Does Phenytoin cause gingival hyperplasia?

Phenytoin is known to cause gingival hyperplasia (enlarged gums). To avoid this, you must maintain a good dental hygiene (taking proper care of your teeth and gums). Please consult your doctor if you have enlarged gums after taking Phenytoin.

Q. Does Phenytoin cause osteomalacia?

Osteomalacia (softening of the bones) has been associated with long-term (>10 years) use of Phenytoin by patients with chronic epilepsy. There have been reports of bone disorders including osteopenia (reduced protein and mineral content of bone tissue) and osteoporosis (thinning of the bone) and fractures with Phenytoin. Please consult your doctor for further information.

Q. Can I take Phenytoin with aspirin?

Phenytoin can decrease the levels of aspirin by increasing its metabolism (breakdown) and hence decrease its effect. Please consult your doctor before taking the two medicines together.

Q. Can I take Phenytoin with ibuprofen?

Phenytoin can be taken with ibuprofen. No drug-drug interactions have been reported between the two. However, interactions can occur. Please consult your doctor before taking the two medicines together.

Q. Can I take Phenytoin with paracetamol?

Phenytoin decreases the level of paracetamol by increasing its metabolism (breakdown). Increased metabolism of paracetamol can increase the levels of substances that can cause liver damage. Please consult your doctor before taking the two medicines together.

Q. Is Phenytoin a narcotic?

Phenytoin is not a narcotic substance. Phenytoin belongs to a group of medicines known as anti-epileptic medicines, these medicines are used to treat epilepsy.

Q. Is Phenytoin a controlled substance?

Phenytoin is not a controlled substance under the Controlled Substance Act (CSA). A controlled substance is generally a drug or chemical whose manufacture, possession or use is regulated by a government.

Q. Is Phenytoin dialyzable?

Phenytoin is not dialyzable by a conventional hemodialysis machine but can be dialyzed by a high permeability type of hemodialysis. To know more about the different types of dialysis and dialysability of Phenytoin, please consult your doctor.

Q. Is Phenytoin teratogenic (cause birth defects)?

Phenytoin is teratogenic. Based on human experience, Phenytoin is suggested to cause congenital malformations (birth defects) when given during pregnancy. It can cause defects of the heart, brain, fingers and can decrease the growth of the unborn baby.

Q. Is Phenytoin a cytochrome P450 (CYP450) inducer?

Cytochrome P450 (CYP450) is an enzyme which causes metabolism (breakdown) of many drugs. Phenytoin is a CYP450 enzyme inducer (increases the working of CYP450) causing increased breakdown of some medicines given along with Phenytoin (known as drug-drug interactions). Please consult your doctor before taking any medicines along with Phenytoin as it may affect the metabolism of the medicines which are metabolized by CYP450 for example Vitamin D.

Q. Is Phenytoin basic or acidic?

Phenytoin is a weakly acidic drug.

Q. Is Phenytoin addictive?

Phenytoin has not been reported to have any addictive potential and it does not show any symptoms of dependence. However, it should be taken for the duration as advised by your doctor.

Q. Does Phenytoin get you high?

Phenytoin does not give you a high.

Q. Does Phenytoin cause hyponatremia?

Phenytoin does not cause hyponatremia (low sodium levels). However, Phenytoin is known to cause hypernatremia (high serum sodium level >145 mmol/L).

Q. Does Phenytoin cause QT prolongation?

Phenytoin is not known to cause QT prolongation (abnormal heart rhythm). However, it can rarely cause abnormal heart rhythms. Please talk to your doctor if you have any abnormal heart rhythm (beats) while taking Phenytoin.

Q. Does Phenytoin affect thyroid?

Thyroid function may get affected while you are taking Phenytoin, especially in children. Thyroid function should be monitored while taking Phenytoin. Please consult your doctor if you have hypothyroidism or a history of hypothyroidism.

Q. Does Phenytoin cause weight gain?

Phenytoin has not been reported to cause weight gain. However, weight loss can occur with longer term use of a higher dose of Phenytoin. Please consult your doctor if you experience weight gain after taking Phenytoin.

Q. Does Phenytoin make you sleepy (sedation)?

Phenytoin can make you feel sleepy (sedation, somnolence, and drowsiness). Please consult your doctor if you feel very sleepy after taking Phenytoin, especially during the first few weeks of treatment or following a dose increase. Talk to your doctor as you may be advised not to drive or use machines until it is established that your ability to perform such activities is not affected.

Q. Does Phenytoin affect birth control?

Phenytoin does affect birth control. Phenytoin can decrease the effect of oral contraceptives (birth control pills) which can make the contraceptive (birth control) effect unreliable. Please talk to your doctor if you are asked to take the two medicines together as you may need to use extra protection for birth control.