Health Guide
Drug Guide

Fosphenytoin (Injection route)



Brand Names:

Dosage Forms:


Injection route(Solution)

The rate of IV fosphenytoin sodium administration should not exceed 150 mg phenytoin sodium equivalents (PE) per minute because of the risk of severe hypotension and cardiac arrhythmias. Careful cardiac monitoring is needed during and after administering IV fosphenytoin sodium. Although the risk of cardiovascular toxicity increases with infusion rates above the recommended infusion rate, these events have also been reported at or below the recommended infusion rate. Reduction in rate of administration or discontinuation of dosing may be needed .





Hydantoin (class)

Uses of This Medicine:

Fosphenytoin injection is used to control certain types of seizures (convulsions) in the treatment of epilepsy. It is also used to prevent and treat seizures that occur during brain surgery. This medicine is an anticonvulsant that works in the brain tissue to stop seizures.

This medicine is to be given only by or under the direct supervision of a doctor.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of fosphenytoin injection in the pediatric population. Safety and efficacy have not been established.

Older adults

Appropriate studies on the relationship of age to the effects of fosphenytoin injection have not been performed in the geriatric population. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require caution and an adjustment in the dose for patients receiving fosphenytoin injection.


Pregnancy CategoryExplanation
All TrimestersDStudies in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy in a life threatening situation or a serious disease, may outweigh the potential risk.


Studies in women breastfeeding have demonstrated harmful infant effects. An alternative to this medication should be prescribed or you should stop breastfeeding while using this medicine.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

A nurse or other trained health professional will give you this medicine in a hospital. This medicine is given as a shot into one of your muscles or through a needle placed in one of your veins.

Your doctor will only give you a few doses of this medicine until your condition improves. You will be switched to an oral medicine that works the same way. If you have any concerns about this, talk to your doctor.

Precautions While Using This Medicine:

It is very important that your doctor check your progress closely while you are receiving this medicine. This is to see if the medicine is working properly and to allow for a change in the dose. Blood tests may be needed to check for any unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away. Your doctor may want you to join a pregnancy registry for patients taking a seizure medicine.

Do not receive this medicine while you are also taking delavirdine (Rescriptor®). Using these medicines together may cause delavirdine to not work as well for you.

This medicine may cause some people to become dizzy, lightheaded, faint, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert and able to see well.

Do not stop using this medicine without first checking with your doctor. Stopping the medicine suddenly may cause your seizures to return or to occur more often.

Stop using this medicine and tell your doctor right away if you develop a fever; rash; swollen, painful, or tender lymph glands in the neck, armpit, or groin; unusual bleeding or bruising; or yellow eyes or skin. These may be symptoms of a serious and life-threatening condition called Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS).

If you develop a skin rash, hives, or any allergic reaction to this medicine, stop using the medicine and check with your doctor as soon as possible.

Tell your doctor right away if your skin feels like it is burning, crawling, or itching, or if you have numbness, prickling, "pins and needles", or tingling feelings after receiving fosphenytoin injection.

This medicine may cause purple glove syndrome. Tell your doctor right away if you have skin discoloration, pain, or swelling at the injection site after receiving this medicine.

This medicine may affect blood sugar levels. If you notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor.

Birth control pills may not work while you are using this medicine. To keep from getting pregnant, use another form of birth control along with your birth control pills. Other forms include a condom, a diaphragm, or a contraceptive foam or jelly.

Avoid drinking alcohol while you are receiving this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur:

More common
Blurred vision
dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
feeling of warmth or heat
flushing or redness of the skin, especially on the face and neck
unusual tiredness or weakness
Less common
burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
changes in patterns and rhythms of speech
difficulty with speaking
dry mouth
fast, pounding, or irregular heartbeat or pulse
itching skin
lack of coordination
large, flat, blue, or purplish patches in the skin
loss of balance control
muscle trembling, jerking, or stiffness
problems with movement, walking, or speech
shakiness in the legs, arms, hands, or feet
shortness of breath
shuffling walk
slurred speech
stiffness of the limbs
trouble with sleeping
twisting movements of the body
uncontrolled movements, especially of the face, neck, and back
unsteadiness, trembling, or other problems with muscle control or coordination
Abdominal or stomach pain
absence of or decrease in body movement
aggressive or angry
black, tarry stools
bleeding gums
bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
blistering, burning, crusting, dryness, or flaking of the skin
blood in the urine or stools
bloody nose
bluish color of the fingernails, lips, skin, palms, or nail beds
body aches or pain
bone pain
burning while urinating
change in consciousness
change in personality
change in the ability to see colors, especially blue or yellow
change in the color of the treated skin
chest pain or discomfort
cloudy urine
cold, clammy skin
cough or hoarseness
cough producing mucus
coughing or spitting up blood
decrease in frequency of urination
decrease in the amount of urine
deep or fast breathing with dizziness
difficulty in passing urine (dribbling)
difficulty with breathing
difficulty with moving
difficulty with swallowing
dilated neck veins
dizziness, fainting, or lightheadedness
dryness or soreness of the throat
eye pain
feeling of unreality
feeling that others are watching you or controlling your behavior
feeling that others can hear your thoughts
feeling, seeing, or hearing things that are not there
fever or chills
flushed, dry skin
frequent urination
fruit-like breath odor
general feeling of discomfort or illness
general physical wasting or malnutrition associated with severe illness
greatly increased frequency of urination or amount of urine
headache, severe and throbbing
hives or welts
inability to move the legs or arms
inability to sit still
increase in body movements
increase in heart rate
increased hunger
increased sensitivity of the skin to sunlight
increased thirst
increased urination
increased volume of pale, dilute urine
increased watering of the mouth
irregular breathing
itching, scaling, severe redness, soreness, or swelling of the skin
joint pain
leg cramps
loss of appetite
loss of bladder control
loss of consciousness
loss of memory
loss of strength or energy
lower back or side pain
muscle aches, pains, or stiffness
muscle twitching or jerking
muscular tenderness, wasting, or weakness
nausea or vomiting
need to keep moving
no blood pressure or pulse
not breathing
numbness of the feet, hands, and around the mouth
numbness or tingling in the face, arms, hands, feet, or lips
pain or tenderness around the eyes and cheekbones
pale skin
paralysis of one side of the body
pinpoint red spots on the skin
pounding in the ears
problems with memory
quick to react or overreact emotionally
rapid breathing
rapid heartbeat
rapid weight gain
rapidly changing moods
rash with flat lesions or small raised lesions on the skin
redness of the skin
redness or other discoloration of the skin
rhythmic movement of the muscles
sense of detachment from self or body
severe constipation
severe headache
severe mood or mental changes
severe pain in the chest
severe sunburn
severe vomiting
small lumps under the skin
small red or purple spots on the skin
sores, ulcers, or white spots on the lips or in the mouth
spots on your skin resembling a blister or pimple
stiff neck
stopping of heart
stuffy or runny nose
sudden onset of severe breathing difficulty
sudden shortness of breath or troubled breathing
sunken eyes
swelling of the face, fingers, feet, ankles, or lower legs
swelling of the tongue
swollen joints
swollen, painful, or tender lymph glands in the neck, armpit, or groin
tightness of the chest or wheezing
troubled breathing with exertion
twisting movements of body
unable to sleep
uncontrolled movements, especially of the face, neck, and back
unexplained weight loss
unusual behavior
unusual bleeding or bruising
unusual weak feeling
voice changes
vomiting of blood or material that looks like coffee grounds
weakness or heaviness of the legs
weight gain
wrinkled skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
Continuing ringing or buzzing or other unexplained noise in the ears
decreased awareness or responsiveness
hearing loss
severe sleepiness
sleepiness or unusual drowsiness
uncontrolled eye movements
Less common
Back pain
change in taste or bad, unusual, or unpleasant (after) taste
change in vision
double vision
feeling of constant movement of self or surroundings
impaired vision
lack or loss of strength
pelvic pain
seeing double
sensation of spinning
Acid or sour stomach
bigger, dilated, or enlarged pupils (black part of eye)
burning feeling in the chest or stomach
burning, dry, or itching eyes
change in color vision
difficulty having a bowel movement (stool)
difficulty seeing at night
discharge, excessive tearing
ear pain
excess air or gas in the stomach or intestines
frequent urge to defecate
full feeling
increased sense of hearing
increased sensitivity of the eyes to light
itching of the vagina or genital area
loss of taste
pain during sexual intercourse
passing gas
redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
stomach discomfort, upset, or pain
straining while passing stool
tenderness in the stomach area
thick, white vaginal discharge with no odor or with a mild odor
transient, mild, or pleasant aromatic odor
vaginal yeast infection
weight loss

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 9/15/2016

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