Zarontin (Ethosuximide)

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Zarontin Brand
Dosage Quantity & Price
Ethosuximide (Generic alternate to Zarontin) Generic

We don't sell this generic-version medication.

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Table of contents:

Zarontin is an anticonvulsant used to treat certain types of seizures, particularly absence seizures (formerly known as petit mal seizures). The active ingredient is called Ethosuximide. Ethosuximide is in a class of medications called anticonvulsants. It works by reducing the abnormal electrical activity in the brain that can cause seizures.

Zarontin may be used alone or in combination with other medications to treat epilepsy, but it should only be taken under the guidance of a healthcare professional. It is thought to act by binding to the calcium channels in the T-type of the thalamic neurons to block the low-threshold spikes that are responsible for the rhythmic activities in the thalamic pacemaker. By doing this, it can help prevent certain types of seizures, particularly absence seizures (petit mal seizures).

Uses and Dosage

Zarontin comes in the form of apsules to take by mouth with or without food as directed by your doctor, usually once or twice daily.

Dosage is based on your age, medical condition, blood levels of ethosuximide, and response to treatment. For children, the dosage may also be based on their weight. However, the initial dose for patients 3 to 6 years of age is one capsule (250 mg) per day; for patients 6 years of age and older, 2 capsules (500 mg) per day. The dose thereafter must be individualized according to the patient's response.

Your doctor will start you on a low dose and slowly increase your dose. It may take several weeks or months to reach the best dose for you and to get the full benefit from this medication. Use this medication regularly to get the most benefit from it. To help you remember, use it at the same time(s) each day. Do not stop taking this medication without consulting your doctor. Some conditions may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased.

Side Effects

Common Side Effects of Zarontin (Ethosuximide):

  • Diarrhea
  • Dizziness
  • Feeling tired
  • Headache
  • Hiccups
  • Loss of appetite
  • Nausea
  • Stomach pain
  • Swelling in your tongue or gums
  • Trouble concentrating
  • Upset stomach
  • Weight loss

Serious Side Effects of Zarontin (Ethosuximide):

  • Aggression
  • Agitation
  • Anxiety
  • Burning in your eyes
  • Chest pain
  • Chills
  • Confusion
  • Depression
  • Easy bruising or bleeding
  • Extreme fear
  • Fever
  • Fly symptoms
  • Hallucinations
  • Hostile behavior
  • Hyperactivity (mental or physical)
  • Impulsive behavior
  • Irritableness
  • Joint pain or swelling with fever
  • Mood or behavior changes
  • Muscle aches
  • Muscle weakness
  • New or worsening cough
  • Panic attacks
  • Patchy skin color
  • Restlessness
  • Severe tingling or numbness
  • Skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling
  • Sore throat
  • Swelling of your face or tongue
  • Swollen glands
  • Thoughts of hurting yourself
  • Trouble breathing
  • Trouble sleeping
  • Unusual thoughts or behavior
  • Upper stomach pain
  • Vomiting
  • Weakness
  • Worsening seizures
  • Yellowing of the skin or eyes (jaundice)

Form and strength

Zarontin (Ethosuximide) is available in the following forms and strength:

Zarontin: Capsule

  • 250 mg


  • Patients should avoid alcohol consumption while taking Zarontin, as it may increase the risk of side effects.
  • Serious problems can occur when people stop taking Zarontin, and patients should consult their healthcare provider before discontinuing the medication.
  • Zarontin may cause a rare but serious blood disorder called systemic lupus erythematosus (SLE) or lupus-like syndrome, especially in patients with a history of autoimmune disorders.
  • Zarontin may cause psychiatric disturbances or behavioral changes, and patients should inform their healthcare provider if they experience any unusual symptoms.
  • Zarontin may cause side effects such as drowsiness, dizziness, and headache, and patients should avoid driving or operating machinery until they know how the medication affects them.
  • Zarontin should be administered with extreme caution to patients with known liver or renal disease Zarontin may interact with other drugs, so patients should keep a list of all the products they use (including prescription/nonprescription drugs and herbal supplements) and consult their healthcare provider before taking any new medication.

Frequently Asked Questions (FAQ)

How quickly does ethosuximide (Zarontin) work?

It takes about 3 to 5 hours for your body to absorb the pill form of Zarontin and reach peak levels in the blood.

Does ethosuximide (Zarontin) affect sleep?

Yes, ethosuximide (Zarontin) can affect sleep. This medication is known to cause drowsiness. Ethosuximide (Zarontin) can also cause difficulty sleeping and nightmares.

Is ethosuximide (Zarontin) safe to take while pregnant?

Taking ethosuximide (Zarontin) during pregnancy might be harmful to your baby, but there isn't enough evidence out there to be sure of the risks.

It's important to purchase Zarontin from verified Canadian pharmacy.

Additional information

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