Overview

Dilantin is one of the oldest and best studied anti-seizure medications on the market. Although it was first developed in 1908, the drug’s ability to prevent epilepsy wasn’t discovered until 1938.

Dilantin works in part by stabilizing nerve cells and making them less excitable. It also exerts a similar action in the heart and is sometimes prescribed for irregular rhythms or a painful nerve condition that affects the face called trigeminal neuralgia.

Side Effects and Interactions

Dilantin can cause a number of side effects which are more common at higher doses.

Symptoms to be alert for include slurred speech, confusion, clumsiness, tremor, poor coordination, dizziness, drowsiness, uncontrollable eye movements, blurred vision, muscle twitching,
insomnia, headaches, nervousness and hyperactivity. If these adverse reactions do not disappear within a few weeks of starting therapy contact your physician promptly and request a blood test.

If you develop a skin rash call your doctor immediately. This side effect usually calls for the discontinuation of the medicine, though this may require a gradual tapering of the dose and the substitution of another drug.

Other less common side effects include chest pain, nausea, diarrhea or constipation, water retention, numbness or tingling of hands and feet, hair loss, fever, blood changes, weight gain, and liver problems.

Some women note unwanted hair growth on their faces or bodies. Report any symptoms to your physician promptly. Many people who take Dilantin for long periods of time experience overgrowth of the gums. In this case good dental hygiene is especially important. Frequent dental visits are advisable.

A large number of over-the-counter and prescription medications may interact with Dilantin in a dangerous way. This anticonvulsant can interfere with the transplant drug Sandimmune, increasing the risk of rejection. Certain other anticonvulsants may increase Dilantin’s toxicity, as may Prozac or related antidepressants.

Some drugs, such as theophylline or tuberculosis drugs, can reduce the effectiveness of Dilantin and make people more vulnerable to seizures. In addition, Dilantin can interfere with the effectiveness of many other medications, including doxycycline, theophylline, birth control pills and the heart medicine Cordarone.

Other drugs that interact with Dilantin include alcohol, calcium-based antacids, pain relievers containing acetaminophen, folic acid, quinidine heart drugs, the blood thinner Coumadin, certain antidepressants and the ulcer medicines Tagamet and Prilosec.

Do not take any other medication without first checking with your physician and pharmacist.

Special Precautions

Determining the proper dose of Dilantin is not always easy. Some individuals metabolize this medicine more rapidly than normal and may need higher amounts. Others, especially older people or those with liver problems may need lower doses or a different anti-seizure medication to avoid toxicity.

Periodic blood tests can help determine if the dose is appropriate. Diabetics will need to be even more careful than usual in monitoring blood sugar. Dilantin may interfere with normal control.

Taking the Medicine

Dilantin is best taken at meal time to increase absorption and reduce the risk of stomach upset. Do not swallow your pill with milk, however, or take it at the same time you eat foods high in calcium, as this mineral may reduce the effectiveness of your medicine.

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  1. Liz
    Oxford
    Reply

    I was put on Dilantin originally when I was first diagnosed backed when in 1968. I went through school and college not being able to read because of a very bad case of medically induced dyslexia caused by the Dilantin. Yes, I got through school and my first 15 years of my career realitvity seizure free because of Dilantin. I also had a very, very hard time reading at this time because of the side -effects. When my new doctor (second neurologist) took me off Dilantin, I was so happy! I could finally read.

  2. Elizabeth
    Uk
    Reply

    I’m on phenytoin, been on it for 40 years and I am, trying to wean myself off it. I have gone from 200 mg to 150mg per day . Got headaches. Phenytoin affected my thyroid so am on thyroxine meds too. These medicines deplete the body of so many neutrients and minerals, I try to eat healthy but so many foods seem to interact with one or both of these medicines. Advice in gettin off phenytoin?

  3. RAJESH A.
    Mumbai
    Reply

    I’m on Dilantin Phenytoin Sodium daily, 3 doses of 100 mg, for the past 15 years. I have had no stroke or seizure for the last 11 years, and my serum level is also normal. But I am having the following side effects: infertility, floaters in my eyes, fluctuations in blood pressure, extreme weakness, and 24-hour vertigo. But I have a seizure-free working life.

  4. Sharon
    canada
    Reply

    I am interested in knowing as much as possible about Dilantin (I have been on it for 30 years) and now Dr. wants to chge to Keppra. I am terrified to chge drugs at this late date and have been seizure free with Dilantin. The reason for change is the side effects of Dilantin but…….Keppra is just as scary so I really do not know which way to turn. I feel changing to another drug at this late date is not for myself — . I do not really have any bad side effects from the Dilantin and why should one start all over again with a new drug just because it may not cause 1 or 2 or the side effects …..they can all be challenging and I feel we need to be our own advocate. Your thoughts.

  5. CLARICE
    SUN CITY, ARIZONA
    Reply

    I have been on Phenytoin since 2007. I have not had a seizure since I started taking it, and there have been no side effects; however, I am now having a side effect that concerns me. I feel like my gums are swelling and this swelling causes my lips to look larger. I brought this up to my neurologist’s attention, but she doesn’t feel that it is bad enough to take me off the medication. I’m afraid that soon I may begin to have a grotesque look. Has anyone suffered he same side effect, and what did you do about this? Also, once I get off Phenytoin, will this swelling reduce? Please let me know if you have suffered this side effect too. Thanks.

    • kathleen
      tennessee
      Reply

      My husband is recently diagnosed with FTD includes partial seizures, he was prescribed Keppra-it almost “killed” him. I am an R.N. 40 yrs asked his doc to prescribe Dilantin 100mg twice a day, he still doesn’t feel well BUT past few days no partial seizures!

      I do not like these “new miracle” drugs I think they are hurting patients more than helping. Dilantin has been around a long time, if its been working for you stick with it. My husband is a retired physician, I worked in his office past 10 yrs, saw lots of drug reps–their drugs “the best” they just want to sell their meds. STAY on what is working for you is my best advice. In fact I got our doc to prescribe Dilantin, an oldie but goodie! Stay Healthy Kathleen

    • Christine
      Richland wa
      Reply

      My previous neurologist also put me on keppra. Keppra has side effects too. Ive been on dilantin for 28 yrs and have been seizure free. These doctors always want to change meds. I say if your doing good then dont. Dilantin does require more frequent lab work and it does affect thyroid med BUT it also prevents seizures and thats worth all the labs to me. I had to wean off of keppra and i literally thought i was losing my mind. I stayed on dilantin while on keppra. Take your B vitamins and Biotin w dilantin and check your levels regularly. I do best at 17. Good luck (:

  6. J. Green
    Reply

    I began having Grand Mall seizures at the age of 18 right before starting college at UTC. I started taking Dilatin as prescribed by my doctor. The migraines were so excruciating that I missed 70% of my classes. Sunlight was too intense for me to endure. I was embarrassed and scared to be around people. My muscle mass and bone density decreased so significantly that I was forced to to workout twice a day everyday. A neurologist tried to switch me to Keppra that hospitalized me for weeks at Erlanger nuerology department.
    I was labeled disabled and had my license taken. These medicines have ruined my life. I was a pre med major looking to go to med school and change lives. Now i’m scared I may have a stroke in my sleep. My hair is thinning and I cannot maintain weight. Sadly, nothing out there on the market can help. My prayers are with all of you.

    • Mary
      Pennslvania
      Reply

      Did you ever try Topamax Brand Necessary? This medicine seems to be helping my daughter. She still gets seizures around her cycle time. The generic one causes more seizures. It’s called Topiramate. Our prayers are with you and best of luck to you!

    • tess
      USA
      Reply

      DEAR J. It’s been 3 years since you posted, but I just had to respond and tell you I won’t forget your story. I very much hope there has been change for the better in your health, and life, since then. Kind regards.

  7. jb
    Reply

    I agree with Graeme. They do only care about $$$ when it comes to patient health. One neurologist put me on freakin’ Keppra, knowing full well that it would not work at all. I told him I have tonic-clonic seizures, just as my chart specified. I begged him not to put me on it, as it would cause more problems than the Dilantin (Phenytoin) I was already on. Needless to say, as soon as I was off the Dilantin, I had multiple seizures, and was so physically damaged I was bedridden.
    I was closer to death than I ever was. I really thought I was on my death bed. I went back on Dilantin against his orders,then never went to him again. Problem is, they are all like that, as I soon found out. We truly are at the criminals mercy. It does certainly suck!

  8. c.b.
    Reply

    I started having seizures 20 years ago after witnessing my best friend shot and killed at the gym I worked at then. The seizures started out as Grand Malls and then with every imaginable medication tried over the years, and all the same problems you’ve mentioned they (the doctors) were able to get them down to mini Petite malls in my sleep. Now still from time to time I have one. I’ve been on Topamax and Phenotin (generic Dylantin). I literally workout three or more hours a day to keep my weight down when I’m teaching fitness sometimes more. I found this site by accident because I’m looking for a weight loss miracle when on both of the Meds. I may only be 7 pounds overweight, if that. Although if I didn’t kill myself in exercise every day to keep it down I think I would really have a problem. Any Help ?
    C.B.

  9. Ron
    Reply

    I have been on Dilantin for around 54 years and the only side affect I have thus far is when my Doctor raised my daily use from 4 pills a day to 5 pills a day and it took my Dilantin level from 10.5 to 35. This put me in the hospital for two days and another Doctor the hospital wanted me to see wants to switch me off Dilantin to Trilepta or Keppra. I tried Keppra as my Doctor instructed which was take 1 – 500mg tablet in the morning and 1 – 500mg tablet at night while still taking my regulator daily Dilantin medication. With in two days of taking Keppra and Dilantin it made me feel tired, enclosed, headaches, edgy and chest pains. I called my doctor and explained all of this and told I am getting off the Keppra for the time being. In going over the side affects Keppra & Trileptal is worse then Dilantin, what is best to switch to if I want to get off Dilantin?

  10. Graeme
    Reply

    Hi Donna,
    I am sorry for taking so long to reply to the email you sent me, and by the way thanks! Well it makes me happy that someone out their can see what these horrible meds are doing to people’s lives, and that the pharmaceutical companies got off their back sides and started to spend the money their given on finding a cure.
    I mean, epilepsy has been around for decades, let me tell you what anti epileptic medication did to my life. In 2008 I was introduced to a doctor he told me I needed an extra medication to control my seizure activity, so I not knowing any different went along with his advice, I was already on dilantin and showing signs of side effects from it. This new fantastic med was topamax and was to become my worst nightmare.
    In 2010 just 2 years of being on a mixture of topamax and dilantin I started to show signs of what I was to be diagnose as psychosis, I also had ocd disorder, I tried to take my life on a number of occasions, my hair began to fall out I developed the syndrome to which I have to this day called (gynecomastia) where a male produces breasts. In 2010 I was involuntarily committed to the acute mental hospital, where I stay for 2 months.
    Then anti psychotic meds were added to my total list of medications I was a totally different person to what I was when I walked into the doctor surgery that day to be put on topamax, I was a mess. I tried to commit suicide while in hospital, I was released and went back to hospital in 2011 for a short stay, I am currently under a psychologist councilor and a g.p. myself the councilor and the g.p. are going to review my meds.
    This is my true life experience with anti epileptic medications which I believe are a lot more damaging to the body and mind then what the average person is aware of. Prescribed medications can make you look into a mirror and you start seeing a totally different person looking back.
    You see Donna it’s like you and me and all the other people out there who have epilepsy, or aids or cancer or have to rely on medications to have a quality of life the companies are only in it for the money so are the doctors you and I go to see, no one cares about peoples health really, or else why would they take such stupid chances with these dangerous medications.
    I mean how much more dangerous can you get in a medication that turns you into a schizophrenic and you start trying to commit suicide.
    Graeme.

  11. David
    Reply

    About 20 years on Dilantin, dose gradually increased over the years, now at 550mg/day. Seizure-free for several years. Generally speaking, I have relatively few side effects. I have lost hair on my head, but male pattern baldness runs in the family, so can’t necessarily blame the Dilantin for that. Everywhere else, I do have a fair amount of hair growth, including back, hair, and a bit on the shoulders; but once again, I have no way of distinguishing if this is natural, or related to the Dilantin.
    All I do know is Dilantin works for me. Brand, not generic; as others mentioned, got generic by substitution once, and had a seizure within a few days. Blood level showed less than half what it should be. “Equivalent” my a$$. Have also tried (individually) Keppra, Zonegran, Lamictal, and Topamax, with no luck. Could never wean off the Dilantin, even on the highest doses of the others.

  12. Donna
    Reply

    I have been on Dilantin for years, but recently the dose was upped to 500mg. I’m noticing some hair loss and great amt of weight gain. When I was on Topamax, I had an extreme amt of hair loss. Since it wasn’t helping my seizures anyway, I was taken off of it. I agree with you totally and wish you the best of luck!

  13. MA
    Reply

    Females: Anyone else suffering breast pain from this drug, particularly the generic?
    Wes, I so agree w/ you!!I have tried so many seizure drugs, its crazy! I have a choice now betw. Dilantin and all of its horrible side effects or serious seizures! What kind of a damn choice is that!

  14. Ginger
    Reply

    With the help of my doctor, I have weaned myself off dilantin. However, I have gained weight, not just a few pounds, but about 15 in 6 months. Can this be the result of stopping dilantin?

    • halim
      addis
      Reply

      Am phenytoin for the last seven years.
      I have seizures when I make a dose change, but now I want out of it. I know I will have seizure when I off. As my blood used to it will not have again hopefully.

  15. wes
    Reply

    I have been on Dilantin now for 8 years it wasn’t until a about 3to4 years ago I started noticing changes in my body the hair on my body was getting thicker especially on my arms and underneath my arms the hair was growing to a point where I knew something wasn’t right, I brought it to my doctor’s attention and he knew the medication may have been the cause, but nothing was ever mention about Dilantin causing hair loss in 2008 another medication was added Topamax this I was told could cause hair loss it is 2012 and I am starting to suffer the consequences of these 2 medications.
    All I can say for those people like me in this situation is unless the companies who research and make these medications don’t focus on creating a medication that targets the problem only instead of giving you added problems to deal with then epilepsy might as well be in the same category as cancer.
    Thanks Wes.

  16. V. Spirk
    Reply

    I have been on Dilantin since January 2011. I find taking some yogurt helps with the upset stomach I get from the medication. I also have noticed that I have gained some weight since I started (about 20 lbs.) I am also a diabetic and have been for 41 years. I would like to hear from some other long standing diabetics who are taking Dilantin. I have NOT had any epileptic seizures since I started taking it.
    V. Spirk

  17. Stephanie K.
    Reply

    Our 36 year old autistic son has been on Dilantin for 25 years. One year ago he was diagnosed with the onset of Osteoporosis.
    Consequently we added calcium w/ Vitamin D. About one month ago we added some food and drinks that was fortified with Calcium. On 3/27,2011 he was admitted in the hospital with nonstop seizures. His Dilantin level dropped 10 points from his therapeutic level. We suspect that the added calcium may have caused his level to drop. If anyone else has had this experience we would be interested to hear.

  18. LK
    Reply

    Question: I’ve been having a fever and headaches and extremely weak and tired for almost 5 months. General Practitioner can see nothing wrong in the blood work. I was referred to immunology/allergy where much testing was done with a sinus polyp found and oropharygeal contamination. So would these findings cause the symptoms of headache, fever, and extreme weakness? Or could these symptoms relate to the 300 mg of dilantin taken daily and the 600 mg of Tegretol taken daily? I’ve taken dilantin for 45 years and tegretol for 30 years.
    An answer to this would be appreciated. I do have an apt. with my neurologist next Thursday.
    LK

  19. Bonnie
    Reply

    I am a 39 year old single mom who has been suffering major hair loss for almost ten years. I can’t remember the last time I had used a hair brush on my hair. I used to have long beautiful blond hair now I deal with my bathroom floor being covered in hair all the time. I at times start to panic thinking I have cancer or something like that. I have been on Dilantin for years for seizures. Is it possible that maybe the dilantin is whats causing my major hair loss?

  20. Kathy
    Reply

    My husband’s dilatin was changed by the mail in pharmacy to the new generic form without notification.  My husband started taking the generic form and within 5 days started feeling bad.  He said he just hurt all over and had a headache.  I checked his medication and realized what had happen.  I call our family doctor and explained to him that the mail in pharmacy had replaced his dilatin with the generic form.  He had my husband come in and ran a blood test for dilatin level and the result were the level was low.
    We immediately got a new prescription and filled it at a local pharmacy.  I called the mail in pharmacy and had to sent new orders to them with brand name medically necessary. We have to do this every time we fill his prescription because they say, to cut cost they are required to dispense the generic for cost savings due to requirements of the insurance companies.  The average consumer needs to be educated on this practice. I feel the brand name drugs have too high a cost and the insurance companies have too much control over what is being dispensed.
    This leaves the consumer at the mercy of the drug and the insurance companies. I thought the doctor who is caring for his patients and has the patients history/information should be in charge.

  21. DS
    Reply

    I was on Dilantin 400mg daily for 15 years. I suffered from GAD prior to Dilantin, once I started the med the GAD pretty much disappeared. I weaned off Dilantin 7yrs ago and have suffered with GAD ever since. I strongly believe the Dilantin kept the anxiety at under control. I am going to discuss resuming the med with my MD.

  22. Ken
    Reply

    I have had anxiety (GAD) for 33 years. Have tried SSRI’S since 1996 but didn’t tolerate them well. Klonopin has worked pretty well. Have read Jack Deyfus book on treatment of mood disorders with Dilantin. What do you think about the safety of this drug in small 100mg dose?

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