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When and How to Take Phenytoin

Some general considerations for when and how to take the medication include:
  • Phenytoin comes in extended-release capsules, chewable tablets, and an oral suspension. These products are not interchangeable.


  • Phenytoin can be taken with or without food. If it upsets your stomach, try taking it with food. It is important that you take it consistently the same way (either with food or without food).


  • For phenytoin suspension, make sure to shake the medication thoroughly before each dose.


  • Phenytoin chewable capsules may be chewed or can be swallowed whole.


  • Do not chew, crush, or open phenytoin capsules, as they are extended-release products.


  • Phenytoin should be taken at the same times each day to maintain even levels of the drug in your blood.


  • For the medication to work properly, it must be taken as prescribed. It will not work if you stop taking it.


  • Do not stop taking phenytoin without first discussing it with your healthcare provider (see Dilantin Withdrawal).

Dosing Information

The dosage that your healthcare provider recommends will vary depending on a number of factors, including:
  • The particular phenytoin product
  • Your age and weight
  • The amount of phenytoin in your blood (measured using a blood test)
  • Other medications you may be taking
  • Other medical conditions you may have.
As with any medication, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
(Click Phenytoin Dosing for more information.)
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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