Is Singulair safe during pregnancy?

What does the evidence say about Singulair during pregnancy?

1. Published prospective and retrospective cohort studies spanning decades of montelukast use in pregnant women have not established a drug-associated risk of major birth defects. 1
2. A boxed warning covers serious neuropsychiatric events reported with montelukast, and the label directs prescribers to reserve it for allergic rhinitis only in patients who have an inadequate response or intolerance to alternative therapies. 1
3. Most available information suggests montelukast use in pregnancy does not increase the chance of birth defects above the background risk, drawn from record reviews of thousands of pregnancies. 2
4. Studies reporting lower birth weight and earlier delivery with montelukast involved women who often had severe asthma and used more than one medicine, so it is not clear whether the complications trace to the drug, the underlying condition, or other factors. 2
5. Asthma that is not well controlled can raise the chance of complications both for the pregnant person and for the pregnancy, which is why the risk of stopping has to sit alongside the risk of continuing. 2

Is Singulair safe in each trimester?

• First trimester. Stopping asthma medicine on your own after a positive test is one of the more common early-pregnancy mistakes, and asthma that is not well controlled carries its own risks for you and the pregnancy. Published cohort studies spanning decades have not established a drug-associated risk of major birth defects with montelukast. Make any change a conversation, not a decision you make alone.
• Second trimester. Asthma control often shifts through pregnancy, in either direction, so the middle trimester is a natural point to review whether your current plan is still doing its job. If you take montelukast only for allergic rhinitis rather than asthma, this is also the moment to ask whether a nasal spray or antihistamine would do the same work.
• Third trimester. Some studies have reported lower birth weight and earlier delivery among pregnancies where montelukast was used, though the people in those studies often had severe asthma and were on several medicines, so the cause is unclear. That uncertainty is a reason for closer monitoring with your obstetric team, not a reason to stop abruptly.