What Is Phenytoin & What are its Side Effects, Precautions?

What Is Phenytoin and What Does It Do?

Phenytoin is an antiepileptic drug, used in treatment and prevention of epilepsy. It makes the impulses in your brain slower than usual, preventing any seizures and can be recommended for the exact type of seizure by your physician, according to your need. It can also be taken for heart or nerve related pain. You can take the drug by mouth or as intravenous injections. This drug is also known as an anticonvulsant. To understand what phenytoin does, it is important to know the mechanism of its action on seizures.

Your cells mostly interact with each other through controlled electrical signals passing from one cell to the other, telling the body what needs or is desired to be done. At the time of a seizure a change in the electrical signal level of the nerve cells is noticed that increases the signals to an abnormal frequency that is excessive for the body to handle. The result of this unexpected excess flow of signals could be due to stroke, injury to the brain, tumor, metabolic problems, toxicity complications and genetic causes. By keeping impulses down to a nominal level and restricting the flow from becoming excessive and uncontrollable, anticonvulsants such as phenytoin are used to treat an array of disorders such as epilepsy, bipolar disorder and neuropathic pain. This answers your question of what does phenytoin do.

Phenytoin is available as chewable tablets, through oral capsule suspension, oral capsules or oral capsule extended release. The dosage needed by you depends on several factors including age, weight, form of the drug and medication brand, and would be rightly prescribed by your physician.

What Is Phenytoin and What Does It Do?

What Are The Side Effects Of Phenytoin?

Apart from its various uses, phenytoin has a darker tone to it and may cause unwanted side effects. The most common side effects of Phenytoin include slurred speech, problems with coordination, problems with sleeping, confusion, vomiting, dizziness, nervousness and constipations. Most of these are mild symptoms and go away on their own.

However, some side effects of Phenytoin can be fatal. It is known to bring suicidal thoughts in your mind, because of the weakness caused by the drug. This can be accompanied by depression, anxiety, panic attacks, irritation, aggressiveness and cases of extreme activity or talking. Thoughts of self harm and aggression go hand in hand; it’s best to seek immediate medical help in such cases of unusual behaviors.

Other side effects of Phenytoin, on a fatal note, can also cause rashes all over the body. These rashes occur within the first month of taking the drug and can be life threatening, including triggering conditions like toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome (SJS), accompanied by hives on the body and issues in breathing. Your physician will have to stop the medication in this case.

It can also cause multiorgan hypersensitivity which includes fever, rashes, yellowing of skin, muscle pain, constant infections, appetite loss, decrease in urination and nausea. Phenytoin can also reduce your vitamin D levels, leading to a lack of calcium and phosphate, and excessive softening of your bones or osteoporosis. A high intake of the drug can also cause a lot of confusion, known as delirium, or psychosis. To manage these side effects of Phenytoin, the treatment would be stopped and necessary conter action may be considered by your treating physician.

What Are The Precautions To Be Taken When Using Phenytoin?

Phenytoin like any other drug can interact with other drugs and herbs. Hence, as a part of precaution when taking phenytoin, it is necessary that you inform your physician about any other on going medicines.

  • Cardiovascular drugs like amiodarone or ticlopidine can increase your phenytoin levels and cause further symptoms upon interference.
  • Fluvastatin, the cholesterol drug, does the same deed.
  • Other anti seizure drugs, cancer drugs, oral birth control pills, menopause drugs, stomach acid drugs and others increase or decrease your phenytoin levels to the extremities, creating an imbalance in your body which can prove fatal for you.

Other precautions when taking Phenytoin include refraining from alcohol, as it may cause imbalance. Phenytoin should also not be consumed by pregnant women as it can harm the mother and the baby. Also, Phenytoin can pass into the milk of a lactating mother and affect the baby. Breast-feeding should be strictly avoided upon intaking Phenytoin. Hence, for pregnant women and lactating mothers, other options of treatment and seizure control must be discuseed with the physician.

Phenytoin is easily available and can be obtained on physician’s prescription. To take the tablet, you can crush or cut the tablet, but do not do the same with a capsule. If you are consuming an oral suspension liquid, shake it well before you measure a dose. Do use that exact amount in the provided syringe or a measuring spoon before intake. Since it is available in different forms, the method of usage differs. It should also be stored at room temperature and not be exposed to extreme humid or cold climates. It is also safe to carry during travelling, and even better while having the prescription in hand.

Most pharmacies store the generic tablets or capsules of Phenytoin. If your doctor recommends you a special intake, take as advised. You also need to take blood test frequently while consuming this drug. Also, never stop using Phenytoin even if you feel fine, continue to take as advised and consult physician if there is any concern. A sudden break in consumption can also lead to an imbalance in your body. If you happen to miss a dose, take the next one as soon as possible. In case of an overdose, you should immediately seek medical attention. An overdose can prove to be fatal and can be detected by slurring of speech, light-headedness, nausea, problems in breathing, twitching of the eye etc.

Now that you are aware of what is Phenytoin and what it does, you know that it is important to follow medical advice. It would keep your seizures in control and hence, help you lead a smooth life.

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Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:April 30, 2019

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