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Zonisamide Pregnancy and Breastfeeding Warnings

Medically reviewed by Last updated on May 11, 2022.

Zonisamide is also known as: Zonegran

Zonisamide Pregnancy Warnings

Animal studies have revealed evidence of teratogenicity. Fetal abnormalities or embryofetal deaths have been reported in animal tests at dosage and maternal plasma levels similar to, or lower than human therapeutic levels. Therefore, use of this drug in human pregnancy may expose the fetus to significant risk. There are no controlled data in human pregnancy.

To provide information regarding the effects of in utero exposure to this drug, physicians are advised to recommend that pregnant patients enroll in the NAAED Pregnancy Registry. This can be done by calling the toll free number 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website

AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Accompanying texts should be consulted for further details.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

This drug should be used during pregnancy only if the benefit outweighs the risk.

AU TGA pregnancy category: D
US FDA pregnancy category: C

-This drug can harm a developing fetus.
-This drug metabolic acidosis in humans. The effect of metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) may be associated with decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the ability of the fetus to tolerate labor. Pregnant patients should be monitored for metabolic acidosis and treated as in the nonpregnant state.
-Women of childbearing potential should use effective contraception during therapy, and for one month after discontinuation.
-If a woman becomes pregnant while taking this drug, therapy should not be discontinued suddenly as this may lead to breakthrough seizures, which could have serious consequences for both mother and child.

See references

Zonisamide Breastfeeding Warnings

A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

Excreted into human milk: Yes

-This drug is excreted in human milk at a concentration similar to that in plasma.
-Due to the long retention time of this drug in the body, breastfeeding should not be resumed until one month after therapy is completed.

-Limited information indicates that maternal doses of this drug up to 400 mg daily produce high levels in milk and infant serum, but serum levels in neonates decrease during the first month of life while nursing. Although no adverse reactions have been reported in breastfed infants, the number of infants reported have been small. Alternative drugs are preferred, but if this drug must be given, the infant should be monitored for drowsiness, adequate weight gain, and developmental milestones, especially in younger or exclusively breastfed infants and when using combinations of anticonvulsant drugs.
-Some clinicians recommend that mothers taking this drug only partially breastfeed in order to reduce the exposure of the infant to the drug and to consider monitoring the infant serum concentrations.

See references

References for pregnancy information

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. "Product Information. Zonegran (zonisamide)" Elan Pharmaceuticals, S. San Francisco, CA.
  3. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. Available from: URL:" ([2006]):

References for breastfeeding information

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. Available from: URL:" ([2006]):
  3. United States National Library of Medicine "Toxnet. Toxicology Data Network. Available from: URL:" ([cited 2013 -]):
  4. "Product Information. Zonegran (zonisamide)" Elan Pharmaceuticals, S. San Francisco, CA.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.