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Side Effects of Ethosuximide (Zarontin)


Side Effects of Ethosuximide (Zarontin)

Ethosuximde, commonly known as the brand Zarontin, is an anticonvulsant used for epilepsy mainly in the absence of seizures. Absence seizures are characterized by a brief loss and return of consciousness. These are generally not followed by a period of fatigue. These are sometimes referred to as petit mal seizures.

Side Effects

The FDA lists the common side effects:


  • Mental confusion
  • Drowsiness
  • Headache
  • Insomnia
  • Ataxia (loss of control of bodily movements)

There are rare side effects that include paranoid psychosis, increased libido (sex drive), and worsening depression.

Drug Interactions

Drugs that should not be taken for the treatment of absence seizures are carbamazepine (Tegretol, Carbatrol, Epitol), vigabatrin (Sabril), and tiagabine (Gabitril).


Similarly, oxcarbazepine (Trilepetal), phenytoin (Dilantin, Dilantin-125, Phenytek), phenobarbital, pregabalin (Lyrica), and gabapentin (Neurontin, Gralise, Horizant) should not be used in the treatment of these types of seizures because these medications may worsen absence seizures. Be sure to tell your physician about every drug you are taking and about your medical condition. This medication is not advised for patients with liver problems (Zarontin label as reported by the FDA).

About Pharmacogenetic Testing

To potentially lessen side effects and increase the effectiveness of this medication you should take advantage of pharmacogenetics testing. The field of pharmacogenetics grew out of the human genome effort. Pharmacogenetics research has shown there is great variability among individuals with respect to their drug metabolism genes. These genes are responsible for making the enzymes that actually process or metabolize most medications you may take.

Know Your Risk with the Rxight® Genetic Test

The Rxight® test is taken with a simple cheek swab and determines your genetic variability with respect to your drug processing (metabolic) enzymes. Once your physician has your results in hand, he or she may prescribe medications with different dosing or prescribe another drug entirely. This individualized care is different from the trial and error approach to dosing medicine. With the use of pharmacogenetics testing, your physician will have the ability to personalize your care.


To get started on Rxight® call us at 1-888-888-1932 or email us at support@Rxight.com.


Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry

Read more about Rxight® Individualized Medicine