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Date of issue: July 2022, Version: 4

Orlistat is an orally administered gastric and pancreatic lipase inhibitor which reduces the absorption of dietary fat. It is used in conjunction with dietary measures to enhance weight loss in adults who are overweight (BMI ≥25). Systemic absorption of orlistat is expected to be negligible.

The limited data on the use of orlistat in pregnancy do not suggest an increased risk of fetal congenital malformation or miscarriage but are too limited to exclude such risks. There are no data available regarding intrauterine death, preterm delivery, low birth weight or neonatal complication risks.

As orlistat may impair the absorption of fat soluble vitamins (A, D, E and K), there are theoretical concerns that its use during pregnancy may restrict nutrient availability to the fetus. Given that the available fetal safety data are too limited to provide robust evidence-based recommendations regarding use in pregnancy, routine use in pregnancy is not recommended.

Maternal obesity is associated with an increased risk of congenital malformations and adverse maternal and fetal outcomes; weight loss preconception is therefore recommended. Pregnant women with a BMI>30 should be advised to take 5mg folic acid supplementation one month before conception up until the end of the first trimester. Dieting or use of products to lose weight during pregnancy is not recommended.

Experience of orlistat use in pregnancy is limited. Where exposure in the first trimester has occurred, a detailed fetal anomaly scan should be considered in addition to any other antenatal investigations relating to the maternal obesity, and the drug discontinued as soon as pregnancy is diagnosed. Women and health professionals should be aware that antenatal detection of fetal anomalies is compromised with increasing BMI, and that a normal scan is not informative with respect to neurodevelopmental outcomes. Other risk factors which independently increase the risk of adverse pregnancy outcome may be present in individual cases. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

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