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Zileuton Pregnancy and Breastfeeding Warnings

Medically reviewed by Drugs.com. Last updated on Dec 1, 2021.

Zileuton is also known as: Zyflo, Zyflo CR

Zileuton Pregnancy Warnings

This drug should not be used during pregnancy unless the benefit outweighs the risk to the fetus.

US FDA pregnancy category: C

Developmental studies indicated adverse effects (reduced body weight and increased skeletal variations) in rats at an oral dose of 300 mg/kg/day. In rabbits receiving oral dose of 150 mg/kg/day, cleft palates were also reported. This drug and/or its metabolites cross the placental barrier of rats. There are no controlled data in human pregnancy.

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.

See references

Zileuton 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: Unknown
Excreted into animal milk: Yes

Comments: The effects in the nursing infant are unknown.

See references

References for pregnancy information

  1. "Product Information. Zyflo (zileuton)." Abbott Pharmaceutical
  2. "Product Information. Zyflo (zileuton)." Abbott Pharmaceutical (2016):
  3. "Product Information. Zyflo CR (zileuton)." Cornerstone Therapeutics (2016):

References for breastfeeding information

  1. "Product Information. Zyflo (zileuton)." Abbott Pharmaceutical
  2. "Product Information. Zyflo (zileuton)." Abbott Pharmaceutical (2016):
  3. "Product Information. Zyflo CR (zileuton)." Cornerstone Therapeutics (2016):

Further information

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