Ethosuximide (oral)

Ethosuximide, branded as Emeside and Zarontin, is used to treat absence seizures (petit mal seizures) commonly used in the treatment of epilepsy. Ethosuximide is an anticonvulsant that treats the brain tissues in order to control the seizures.


The EEG patterns shown during a petit mal seizure is known as the spike-and-wave discharge, typically with three second cycles. Ethosuximide works by suppressing this discharge in the brain while also increasing the brain's natural ability to withstand the stimuli.

Ethosuximide was approved for medicinal use in 1960, and is on the World Health Organization's List of Essential Medicines. This drug is widely used as the drug of choice for treating petit mal seizures because doctors have found ethosuximide lacks the idiosyncratic hepatotoxicity of other anti-absence drugs on the market.

Conditions Treated

Type Of Medication

  • Anticonvulsant

Side Effects

A side-effect is typically regarded as a secondary, and usually unpleasant, effect of medication that occurs along with the intended therapeutic effect. Side effects experienced by each patient will vary depending on age, sex, gender, ethnicity, general health, disorder or disease. It is typical for a patient to begin experiencing these negative effects when a new medication is being taken for the first time, or after a dosage change. It is possible for a side effect to eventually cause non-compliance with a medicinal treatment if it persists. In some cases, dietary and lifestyle changes may be made to lessen the side effect.

As with any medication it is important for new users to watch for signs of allergic reaction. The initial signs of allergic reaction may be hives, swollen face/tongue/lips, difficulty breathing, dizziness or fainting.

Because this medication alters brain functioning, it is especially important to take note of, and report, any changes that occur in the patient's mood or behavior. Some of these changes may include:

  • Insomnia
  • Anxiety
  • Aggression
  • Depression
  • Hostility
  • Hyperactivity
  • Suicidal thoughts
  • Self-harming thoughts or behavior
  • Impulsivity

This is not an exhaustive list of all the mood changes that may occur as each person will react differently to the medication. Patients should take note of any behavior, thought or mood that seems unusual for them.

There have been some more serious side effects reported after using this medication. While most of these side-effects are rare, if any of these symptoms present it is important to immediately contact your prescribing physician, or pharmacist. These side effects include:

Fever/chills/sore throat and other flu like symptoms
Hallucinations, confusion, extreme fear or unusual thoughts
Worsening seizures
Lupus like symptoms (joint pain, swollen glands, muscle aches, chest pain, vomiting, patchy skin color)
Severe skin reactions (blistering, peeling, swelling)

  • Ethosuximide has caused complications with abnormal liver function in some patients, although this is rare. Some more common, and less serious, side effects are:
  • Upset stomach
  • Nausea
  • Loss of appetite
  • Hiccups
  • Swelling in gums
  • A headache
  • Trouble concentrating
  • Vaginal bleeding
  • Lethargy
  • Waking suddenly in a frightened state
  • Hair growth in abnormal areas of the body
  • Nearsightedness

Some side-effects of this medication may only occur occasionally, may be mild in severity, or do not require any medical attention and may be alleviated at home. If any of these effects persist or become worse users should seek consultation as soon as possible. However there are some side effects that will require immediate medical attention. Users should be advised to contact emergency services if any of these effects are present:

  • Changes in consciousness
  • Irregular, fast, slow or shallow breathing
  • Pale or blue lips
  • Discoloration in fingertips or toes
  • Discoloration, or mottling, of the skin

Please note that this is not an exhaustive list of all side-effects. If any unwanted effects arise after taking this medication, they need to be discussed with a medical professional.

Some of these side-effects may be temporary as the users body adjusts to the new medication, while others may be longer lasting. It is the responsibility of the patient and the prescribing physician to carefully consider all negative effects of the medication and weigh the benefit of the medication against the risks on a case-by-case basis. A physician may decide to treat the side-effects alternatively, lower or discontinue the dose.

The user of this medication should never change doses or stop medication without the oversight and approval from a physician as immediately stopping this medication may negatively impact the neurochemistry in the patient. Abruptly changing the dose may cause side effects or seizures to worsen.

You may report any side effects experienced to the FDA at 1-800-FDA-1088 or through the MedWatch Adverse Event Reporting Program online at


The dosage of this medication will differ from patient to patient depending on each patient's needs. All dosage requirements set by the prescribing physician should be followed as printed on the label. It is important not to start, stop or change dosage without a doctor's supervision and consent.

The following information includes the average doses of this medication. The number of times the medication is taken and doses may vary.

Adults and Children 6 years or Older: Typically begin taking 600mg capsules once a day, or 10mL of syrup. It is common for the dose to change to 20mg maintenance dose that is taken in several divided doses throughout the day once the initial 4-7 days of 250 mg capsules have controlled the absence seizures.

Children 3 to 6 years old: Doses are based on body weight and will be determined by a doctor. Typically doses are 250 mg in capsuls, or 5 ml in syrup form, once a day. Again, it is common for the dose to change to 20mg maintenance dose that is taken in several divided doses throughout the day once the initial 4-7 days of 250 mg capsules have controlled the absence seizures.

Children younger than 3 Years Old: Are dosed on a case-by-case basis with close supervision.

It is common for physicians to increase this medication in small doses of 250 mg every four to seven days until the therapy proves successful in controlling the absence seizures with few or no side effects. Doses exceeding 1.5 g may be prescribed with close supervision by a medical professional.

If a dose is missed, a user may take the medication as soon as possible. If it is nearly time for the next daily dose the next dose may be skipped an the regular dosage and time resumed as quickly as possible. It is important to never double doses. If you have any questions about how to continue your dosage you may contact your physician for guidance, or contact a pharmacist.


This medication may have interactions with herbal supplements, dietary aides, topicals, over-the-counter medications, as well as other prescribed medication. It is imperative that any user discuss all other therapies being used with their prescribing doctor to ensure any avoidable interactions are prevented. While using this medication, do not start, stop or change the dose of any other treatments being used without consulting a physician or pharmacist.

  • Tell your physician if you are using anything of the following, as the effects may be stronger when used in conjunction with oral ethosuximide.
  • Alcohol
  • Muscle relaxers
  • Marijuana
  • Antihistamines (cetirizine, diphenhydramine)
  • Sleep aids
  • Cough-and-Cold Treatments
  • Following are some prescription medications that have reported major interactions with e
  • thosuximide.
  • Acetaminophen
  • Propoxyphene
  • Aspirin
  • Balacet
  • Belbuca
  • Bunavail
  • Buprenex
  • Buprenorphine
  • Naloxone
  • Butrans
  • Darvocet A500
  • Darvocet-N 100
  • Darvocet-N 50
  • Darvon
  • Darvon Compound 32
  • Darvon Compound-65
  • Darvon-N
  • PC-CAP
  • PP-Cap
  • Probuphine
  • Propacet 100
  • Propoxyphene
  • Propoxyphene Compound 65
  • Sodium Oxybate
  • Sublocade
  • Suboxone
  • Subutex
  • Trycet
  • Wygesic
  • Xyrem
  • Zubsolv

There are 631 medications known to cause moderate interactions with ethosuximide, below are some of these medications. For a more complete list patients may consult their pharmacist.

  • Clemastine
  • 40 Winks
  • 999 Cold Remedy Granular
  • Alka-Seltzer PM
  • Tussin
  • Abilify
  • Abstral
  • AccuHist DM
  • All Day Allegra
  • All-Nite Cold
  • Allan Tannate Pediatric
  • Allent
  • AllePak
  • Aller-Chlor
  • Aller-G-Time
  • Bidex
  • Bidhist-D
  • Biodec
  • Biofed-PE
  • Biospec DMX
  • Broncotron
  • Brotkotuss
  • BroveX
  • Butibel
  • Butorphanol
  • Bupap
  • C Phen
  • Clonidine
  • Caffeine
  • Cannabis
  • Clozapine
  • Clozaril
  • Cocet
  • Codahistine
  • Codal
  • Codamine
  • Carbinoxamine
  • Coldamine
  • Codrix
  • Cofex
  • Certuss
  • Cetiri D
  • Comtrex
  • Cylert
  • Cymbalta
  • Cyndal Expectorant
  • Cimzia
  • Cinvanti
  • Clemastine
  • Clindex
  • De-Chlor
  • Divalproex Sodium
  • Efavirenz
  • Emend
  • Endacof
  • Etravirine
  • Ex-Tuss
  • Esgic-Plus
  • Estazolam
  • Etanercept
  • Histadec
  • Histafed LA
  • Histex
  • Hydrogesic
  • Hydron
  • Hydropane
  • Ibudone
  • Infliximab
  • Invega
  • Iobit
  • Isocarboxazid
  • Kisqali
  • Kaletra
  • Kava
  • Kidcare Cough/Cold
  • Lexiva
  • Linhist-LA
  • Lorazepam
  • Lorcet
  • Lortab
  • Lorzone
  • Loxapine

Minor interactions occurred with 11 different medications, including;

  • Adderall
  • Adzenys
  • Benzphetamine
  • Carbamazepine
  • Adzenys
  • Amphetamine
  • Armodafinil
  • Carnexiv
  • Dextrostat
  • Didrex
  • Dyanavel

It is possible for ethosuximide to also interact with certain foods and drinks. As with most medication it is not recommended this medication be mixed with alcohol. Grapefruit juice is also something your physician may ask you to refrain from as it is known to counteract some medications.

Ethosuximide may interact with a patient's diseases or disorders including blood dyscrasias, renal/liver disease, Sle, suicidal tendency, mood disorders or dialysis. If you suffer from one or more of these diseases it is important to ensure clear communication of all affects, past and present, so the risk and benefits are appropriately weighed by your medical team.

As with all medications, overdose is a risk with ethosuximide. Symptoms of overdose may be nausea, vomiting, slowed breathing, decreased alertness or coma. If any signs of overdose present emergency services should be contacted immediately. If you are not sure you are at risk of overdose, you should consult poison control at 1-800-222-1222.


This medication will require regular lab work to ensure your body has a safe reaction to ethosuximide. It is vitally important these appointments are maintained and all lab appointments completed.

If you are currently, or have previously, suffered from mental illness it is important to discuss this with your physician as this medication will change neurochemistry. If you have never suffered from mental illness yourself, but it runs in your family, it is important to discuss this medical history with your prescribing physician as this may allude to a predisposition for mental illness.

It is important that any user of ethosuximide be fully aware that your mental health may alter during the duration of your treatment. This is especially true as patients begin taking the medication for the first time, change doses, or stop the medication. Even patients that have never suffered from mental illness previously, may incur some mental health side effects while adjusting to ethosuximide. 1 in 500 users of this medication have reported having suicidal ideation, or becoming self harming. Some of these side-effects become apparent after a week on the medication. Some of these mental health side effects may present as a fascination with death or dying, withdrawing from interaction, feelings of hopelessness, panic attacks, nightmares, agitation, restlessness, or nightmares. These are not the only ways that mental health problems may present. It is vitally important that any unusual mood or behavioral activity be reported and monitored by a physician. If you live alone, it is advised that you check in on a regular basis with a trusted friend, family member, caregiver, therapist or doctor to ensure no new signs of mental illness have arisen.

Patients that suffer from liver or kidney disease need to weigh the risks and benefits of this medication with their physician. This medication does interact with this disease and a doctor may choose to supervise the medication more closely, or avoid it altogether.

Once you begin taking ethosuximide it is important to let your medical team know before undergoing any sort of surgery, including dental surgery. Ethosuximide has a wide variety of medications that it may interact with, so some medical professionals advise their patients take their medication bottle with them to other doctor appointments as well to ensure each member of their medical team is aware of the medication dosage and schedule before assigning any other therapies.

Ethosuximide syrups may contain sugar and/or alcohol and caution is advised for patients that suffer from diabetes or alcohol dependency. Patients with liver disease should consult with their doctor before taking syrup forms of this oral medication as liver complications may impede the bodies ability to cleanse these ingredients from the system.

This medication may make you drowsy. As a precaution patients should refrain from operating heavy machinery, or driving until they are familiar with how they will react to their new medication. The same is true if the medication dosage is raised.

Patients that are pregnant, may become pregnant or breastfeeding should take this medication only with the close supervision of a doctor. This medication does pass into the breastmilk of a feeding infant, but is unlikely to cause any harm. To be certain, it is best to consult with a physician before breastfeeding.


This medication, as with all prescriptions, should be kept in the bottle it came in from the pharmacist with the original label. This medication should be kept away from excessive moisture (like in a bathroom). Ideally this medication should be kept at room temperature and away from direct sunlight. This medication must be kept out of reach of children.

Medication should be properly disposed of at a facility. Throwing medication in the garbage or down a drain can cause the chemicals to seep into groundwater or consumed by wildlife. Prescription medication can be disposed of at local fire departments, pharmacies, hospitals, clinics and police stations.


Ethosuximide is an anticonvulsant used to treat epileptic absence seizures, otherwise known as petit mal. This medication works by altering the brain chemistry and tissue to prevent the stimulus that causes absence seizures while also strengthening the brain's natural defense against this stimuli.

This medication is not for everyone as it has a long list of medications that may interact with it. Patients suffering from kidney or renal disease will need to discuss the pros and cons of this medication with their physician as impaired liver functioning may prevent this medication from being properly removed from the body.

This medication has been linked to mental health problems including suicidal ideation and self-harming behavior. Any patient experiencing mental health problems will need to take particular precaution when deciding whether or not this medication is right for them.