Dilantin (phenytoin)

Dilantin generic

Dilantin is a brand-name drug that contains the active ingredient phenytoin. This active ingredient is also available as a generic medication. A generic drug is an exact copy of the active ingredient in a brand-name medication.

The generic is considered to be as safe and effective as the original drug. Generics tend to cost less than brand-name drugs.

If you’re interested in using the generic form of Dilantin, talk with your doctor. They can tell you if it comes in forms and strengths that can be used for your condition.

Dilantin side effects

Dilantin can cause mild or serious side effects (also known as adverse effects). The following lists contain some of the key side effects that may occur while taking Dilantin. These lists do not include all possible side effects.

For more information about the possible side effects of Dilantin, talk with your doctor or pharmacist. They can give you tips on how to manage any side effects that may be concerning or bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Dilantin, you can do so through MedWatch.

Mild side effects

Below is a partial list of mild side effects of Dilantin. To learn about other mild side effects, talk with your doctor or pharmacist, or view the prescribing information for Dilantin oral capsules, Dilantin Infatab chewable tablets, and Dilantin-125 oral suspension.

Mild side effects of Dilantin can include:

• nystagmus (eye movements that you can’t control)
• trouble with coordinated movements, such as walking
• slurred speech
• drowsiness
• confusion
• mild allergic reaction*

Most of these side effects may go away within a few days to a couple of weeks. However, if they become more severe or don’t go away, talk with your doctor or pharmacist.

* For more information about allergic reaction and Dilantin, see “Allergic reaction” below.

Serious side effects

Serious side effects from Dilantin aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

• Heart problems, including low heart rate and heart attack. Symptoms can include:
  • dizziness
  • chest pain or pressure
  • shortness of breath
• Liver problems, such as acute (sudden) liver failure. Signs or symptoms may include:
  • jaundice
  • elevated liver enzymes
  • abdominal pain
• Severe skin reactions. Symptoms can include:
  • skin rash
  • blisters
  • peeling skin
• Blood disorders, such as:
  • anemia (low red blood cells), which may cause fatigue
  • low platelets, which may cause bruising or bleeding
  • low white blood cells, which may lead to infection and fever
• Mental health changes, including:
  • new or worsening depression
  • unusual changes in behavior or mood
  • suicidal thoughts or behavior
• High blood sugar.
• Severe allergic reaction.*

* For details about allergic reaction and Dilantin, see “Allergic reaction” below.

Side effects in children

The possible side effects of Dilantin in adults are the same side effects that may also occur in children.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Dilantin. This was a rare side effect in clinical trials of Dilantin oral capsules, Dilantin Infatab chewable tablets, and Dilantin-125 oral suspension.

Symptoms of a mild allergic reaction can include:

• skin rash
• itchiness
• flushing

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

• swelling under your skin, typically in your eyelids, lips, hands, or feet
• swelling of your tongue, mouth, or throat
• trouble breathing

Call your doctor right away if you have an allergic reaction to Dilantin, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Dilantin dosage

The Dilantin dosage your doctor prescribes will depend on several factors. These include:

• the type and severity of the condition you’re using Dilantin to treat
• your age
• body weight (in children)
• the form of Dilantin they prescribe for you
• other medical conditions you may have
• how your body responds to the drug
• the level of the drug in your blood during treatment, which may change over time due to certain factors

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Dilantin comes in the following forms and strengths:

• extended-release oral capsule: 30 milligrams (mg) and 100 mg
• chewable tablets: 50 mg
• oral liquid suspension: 125 mg per 5 milliliters (mL)

The number of tablets, capsules, or teaspoons you’ll take for each dose depends on the form of Dilantin your doctor prescribes. Check your prescription label or ask your doctor or pharmacist if you have questions about how much to take.

Dosage for seizures

Dosage of Dilantin oral capsules:

The recommended starting dose of Dilantin oral capsules in adults is 100 mg. You’ll take this dose three times per day. After 7–10 days, your doctor will likely test the levels of the drug in your blood. The blood levels help guide doctors in adjusting the dosage to the right amount. They may increase your dose and repeat the blood test as necessary to manage your condition. The maximum dosage is 200 mg taken three times per day.

After your seizures are adequately managed, your doctor may recommend switching to a once-daily maintenance regimen. This is typically 300 mg (three 100-mg capsules) taken once daily.

Dosage of Dilantin chewable tablets:

The recommended starting dose of Dilantin chewable tablets in adults is 100 mg. You’ll take this dose three times per day. After 7–10 days, your doctor will likely test the levels of the drug in your blood. The blood levels help guide doctors in adjusting the dosage to the right amount. They may increase your dose and repeat the blood test as necessary to manage your condition. The maximum dosage is 200 mg taken three times per day.

Dosage of Dilantin oral suspension:

The recommended starting dose of Dilantin oral suspension in adults is 125 mg (5 mL, which equals one teaspoonful). You’ll take this dose three times per day. After 7–10 days, your doctor will likely test the levels of the drug in your blood. The blood levels help guide doctors in adjusting the dosage to the right amount. They may increase your dose and repeat the blood test as necessary to manage your condition. The maximum dosage is a total of 25 mL per day.

Children’s dosage

The dosage of Dilantin in children is based on body weight in kilograms (kg). One kg equals about 2.2 pounds (lb). The recommendations for Dilantin’s dosage in children are the same regardless of the form prescribed.

The recommended starting dose of Dilantin in children is 5 mg per kg (mg/kg). This dose is divided into two or three doses each day. After 7–10 days, your child’s doctor will likely test the levels of the drug in their blood. The blood levels help guide doctors in adjusting the dosage to the right amount. They may adjust the dose and repeat the blood test as necessary to manage your child’s condition. In children, the maximum dosage is 300 mg per day.

For example, if your child weighs 10 kg (about 22 lbs), their doctor will likely prescribe a starting dosage of 50 mg taken three times per day.

The number of tablets, capsules, or teaspoons your child will take for each dose depends on the form of Dilantin their doctor prescribes. Check your prescription label or ask your doctor or pharmacist if you have questions about how much Dilantin to give your child.

About taking Dilantin

Below you’ll find information about key dosage issues.

• When to take: You should take Dilantin according to your doctor’s directions. This may be one, two, or three times a day, depending on the form you’re prescribed and other factors. Taking the medication consistently as directed helps keep a steady level of the drug in your body. This helps Dilantin work effectively.
• If you miss a dose: If you miss a dose of Dilantin, take it as soon as you remember it. However, if it’s almost time for your next dose, skip the missed dose. Then take your usual dose at the next scheduled time. Talk with your doctor or pharmacist if you’re unsure what to do about a missed dose of Dilantin.
• Taking Dilantin with food: You should avoid eating at least 1 hour before and 1 hour after taking Dilantin. This is because taking Dilantin with food lowers the level of the drug in your body, which may make it less effective.
• Crushing, splitting, or chewing Dilantin: Dilantin oral capsules should be swallowed whole. Dilantin Infatabs can be chewed before swallowing them, or they can be swallowed whole. Dilantin oral suspension should be swallowed after measuring the dose using an oral syringe or medicine cup. Your pharmacist can provide you with one of these tools. A household spoon may not be accurate for measuring medication doses.
• Length of use: Dilantin is typically used as a long-term treatment. If you and your doctor determine that Dilantin is safe and effective for you, you’ll likely take it long term.

Overdose

Using more than the recommended dosage of Dilantin can lead to serious side effects. Do not use more Dilantin than your doctor recommends.

Overdose symptoms

Signs and symptoms of an overdose can include:

• nystagmus (eye movements that you can’t control)
• trouble with coordinated movements, such as walking
• trouble speaking or slurred speech
• tremor
• stiffness
• sluggishness
• blurred vision
• nausea or vomiting
• low blood pressure
• coma

Severe overdoses of Dilantin may be fatal.

What to do in case of overdose

If you think you’ve taken too much of this drug, call your doctor. You can also call America’s Poison Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

Common questions about Dilantin

Here are answers to some frequently asked questions about Dilantin.

Does Dilantin cause long-term side effects?

Yes, long-term side effects are possible with Dilantin treatment. Long-term side effects can occur during or after treatment, lasting for an extended time or even after treatment ends.

Bone-related side effects have been reported with long-term use of Dilantin in people with epilepsy (seizure disorder). These include:

• decreased bone mineral density
• osteoporosis (weakened bones)
• bone fractures
• decreased levels of certain vitamins and minerals that are important for bone health, including vitamin D, calcium, and phosphate

These side effects were reported with Dilantin oral capsules, Dilantin Infatab chewable tablets, and Dilantin-125 oral suspension.

You and your doctor will monitor for bone-related side effects throughout Dilantin treatment. They may also recommend ways to help prevent these side effects.

Talk with your doctor if you have questions or concerns about possible long-term side effects of Dilantin.

Is Dilantin a controlled substance?

No, Dilantin is not a controlled substance. A controlled substance is a drug the government regulates due to the risk of dependence or misuse. (With dependence, your body needs the drug to function as usual. And misuse is taking a drug in a way other than how a doctor prescribes it.)

However, if you suddenly stop taking Dilantin, withdrawal symptoms may occur. These may include severe seizures (status epilepticus) that do not stop and require urgent medical treatment. To help prevent withdrawal symptoms, if you and your doctor decide to end Dilantin treatment, they’ll instruct you on how to lower your dose gradually before stopping it.

Talk with your doctor or pharmacist if you have questions or concerns about taking or stopping Dilantin.

Can Dilantin be used for pain?

No, Dilantin is prescribed to treat or help prevent certain types of seizures.

Some seizure medications are sometimes used to treat pain, but Dilantin isn’t one of them. For instance, gabapentin (Neurontin) is a seizure medication that’s approved to treat partial seizures. Gabapentin is also approved to treat postherpetic neuralgia (nerve pain due to shingles).

Also, some people might confuse Dilantin with another drug with a similar name. Dilantin is the brand-name version of the seizure drug phenytoin. A medication with a similar name, Dilaudid, is the brand version of hydromorphone. Dilaudid is used to treat severe pain in certain situations.

You can help avoid confusion by describing why you’re taking each medication when sharing your medication list with your doctor or other healthcare professionals.

Dilantin uses

The Food and Drug Administration (FDA) approves prescription drugs such as Dilantin to treat certain conditions. Dilantin may also be used off-label for other conditions. Off-label drug use is when an FDA-approved drug is prescribed for a purpose other than what it’s approved for.

Dilantin for seizures

Dilantin is FDA-approved for the following uses in adults and children:

• to treat tonic-clonic (grand mal) seizures and temporal lobe (psychomotor) seizures
• to prevent and treat seizures during or after brain surgery

For these uses, doctors may prescribe Dilantin with other antiepileptic drugs.

To learn more about your condition and treatment options, see our epilepsy and seizures hub.

Dilantin and children

Dilantin is FDA-approved for the above uses in children of all ages.

Similar drugs

Other drugs are available that can treat your condition. Some may be a better fit for you than others. If you’re interested in finding an alternative to Dilantin, talk with your doctor. They can tell you about other medications that may work well for you.

While not a complete list, the following drugs are similar to Dilantin:

• levetiracetam (Keppra)
• brivaracetam (Briviact)
• carbamazepine (Carbatrol, Tegretol, others)
• cannabidiol (Epidiolex)
• divalproex (Depakote and Depakote ER)
• gabapentin (Neurontin)
• lamotrigine (Lamictal)
• oxcarbazepine (Trileptal)
• perampanel (Fycompa)
• phenobarbital
• pregabalin (Lyrica)
• topiramate (Topamax)
• valproic acid

Dilantin interactions

Dilantin can interact with several other medications. It can also interact with certain supplements as well as certain foods.

Before taking Dilantin, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

Interactions with medications, foods, and supplements

Below is a list of medications, supplements, and foods that can interact with Dilantin. This list does not contain all drugs that may interact with Dilantin. If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Alcohol interaction

It is not safe to consume alcohol while taking Dilantin. If you have questions about the safety of drinking alcohol while taking Dilantin, talk with your doctor or pharmacist.

Dilantin cost and coupons

As with all medications, the cost of Dilantin can vary. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Drug coupons: You can visit Optum Perks for price estimates of Dilantin Infatabs and Dilantin-125. These estimates are based on the use of Optum Perks coupons. Note: Optum Perks coupons cannot be used with any insurance copays or benefits.

Financial and insurance assistance: If you need financial support to pay for Dilantin, or if you need help understanding your insurance coverage, help is available.

A savings card is available for Dilantin. For more information and to find out if you’re eligible for support, visit the manufacturer website.

To learn more about saving money on prescriptions, check out this article.

Generic version:Dilantin is available in a generic form called phenytoin. A generic drug is an exact copy of the active ingredient in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs. To find out how the cost of phenytoin compares to the cost of Dilantin, talk with your doctor or pharmacist.

To learn more about saving money on prescriptions, check out this article.

Save on your Dilantin prescription

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Retail price refers to the manufacturer’s published list price and is up to date as of 3/2023. Retail and discounted prices are U.S.-only and can vary based on region and pharmacy. We cannot guarantee that the discounted price listed here will exactly match the price at your pharmacy. Please contact your pharmacy for the exact price.

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Things to consider when taking Dilantin

If you can become pregnant, consider the following information about pregnancy, fertility, birth control, and breastfeeding.

Dilantin and pregnancy

There are risks to taking Dilantin during pregnancy, including the risk of congenital anomalies (commonly known as birth defects).

However, there are also risks with having untreated seizures while pregnant. (Dilantin is used for treating or preventing certain types of seizures.)

If you’re planning a pregnancy or can become pregnant, talk with your doctor about potential treatment options. Together, you can consider the risks and benefits of your treatment options and decide whether or not you should take Dilantin during pregnancy.

People who take Dilantin or another antiepileptic drug (AED) during pregnancy are encouraged to sign up for the North American Antiepileptic Drug Pregnancy Registry. Pregnancy registries collect information about the outcomes of medication use during pregnancy. This can help healthcare professionals and patients make informed decisions about medication use during pregnancy. Learn more about this registry online or by calling 888-233-2334.

Dilantin and birth control

There are risks to taking Dilantin during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs during Dilantin treatment.

Keep in mind that Dilantin can interact with birth control pills. (For details, see the “Dilantin interactions” section above.) Talk with your doctor about a birth control option that won’t interact with Dilantin.

Dilantin and breastfeeding

It’s not known whether Dilantin should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication.