In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to olanzapine may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your healthcare provider.

What is olanzapine?

Olanzapine is a medication used to treat schizophrenia and bipolar disorder. It is sometimes used with other medications to treat depression. Olanzapine belongs to a group of medications called atypical or second-generation antipsychotics. A brand name for olanzapine is Zyprexa®.

I am taking olanzapine but would like to stop using it before becoming pregnant.  How long does olanzapine stay in my body?

Individuals break down medications at different rates. On average, it takes up to seven days for most of the olanzapine to be gone from the body.

Before making any changes to your medication, talk with your health care provider about the benefits and risks. Suddenly stopping medications like olanzapine might increase the chance for symptoms such as dizziness or stomach upset and may cause a relapse of your symptoms. If you decide to stop taking olanzapine, it is recommended that this be done with the supervision of a health care provider.

Can taking olanzapine make it harder to become pregnant?

In some women, olanzapine can increase the level of a hormone called prolactin. High levels of prolactin can make it harder to get pregnant. However, olanzapine might be less likely to cause hyperprolactinemia than other antipsychotics. If there is concern, a health care provider can check the level of prolactin in your blood.

Can taking olanzapine during my pregnancy increase the chance of miscarriage? 

Most studies have found the chances of miscarriage to be similar to that of women taking similar medications.*

I am currently taking olanzapine and I am already pregnant. Should I stop taking it?

Talk with your healthcare provider before making any changes to this medication. Studies have shown that women with untreated mental illness can have a higher chance for pregnancy complications. *

Only you and your provider know your medical history and can best determine whether or not you should stop taking olanzapine during pregnancy. The benefits of being treated with olanzapine need to be weighed against any concerns to the pregnancy. Remember that untreated mental illness may cause problems for the pregnancy.

Can taking olanzapine during pregnancy cause birth defects in my baby?

Studies have looked at almost 2500 babies born to women who took olanzapine during early pregnancy or throughout the pregnancy. These studies suggest that using olanzapine during pregnancy is unlikely to increase the chance of birth defects above the background population risk. *

Will taking olanzapine during pregnancy affect my baby’s behavior or cause learning problems?

Few studies have looked at the effects of olanzapine on a baby’s brain. More long-term data are needed to learn if exposure to olanzapine during pregnancy has long-term effects on brain development.

Are there other problems associated with taking olanzapine?

Olanzapine may cause weight gain and problems with blood sugar control. This might increase the risk for gestational diabetes. Your health care provider can monitor your blood sugar levels before pregnancy and then again in pregnancy. If you have been taking olanzapine for a while, your health care provider may have already been checking your blood sugar levels and be able to tell you if they have been in the normal range.

I need to take olanzapine throughout my entire pregnancy.  Will it cause withdrawal symptoms in my baby after birth?

There is limited information about using olanzapine during late pregnancy and how a newborn adjusts after delivery. Based on what has been seen with similar medications, babies born to women taking olanzapine near delivery should be monitored for symptoms such as stiff or floppy muscle tone, drowsiness, agitation, difficulty breathing/feeding, or tremors.  Not every newborn will have these symptoms. If they do, the symptoms usually go away in a few days.

Can I breastfeed while taking olanzapine?

Olanzapine is found in low levels (ranging from 1-4% of mom’s dose) in breast milk.  The amount of the medication in breastfed infants’ blood is very low, or even undetectable in some studies. Most reports have not found difficulties in breastfed infants when their mothers were treated with olanzapine. In one study, a small number of infants had irritability, tremor, sleepiness or difficulty sleeping or staying asleep. As with any medication taken while breastfeeding, the infant should be monitored closely for any adverse effects such as poor feeding or sleepiness. Discuss all of your options for breastfeeding with your healthcare provider.*

The father of my baby was using olanzapine when we got pregnant. Should I be concerned?

There are no studies looking at possible risks to a pregnancy when a father uses olanzapine. In general, medications that the father takes do not increase risk to a pregnancy. However, some men using olanzapine may have higher levels of the hormone prolactin, which may interfere with their fertility. For more general information on a father’s exposures, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at*

* Section Updated May 2020

Please click here for references.


National Pregnancy Registry for Atypical Antipsychotics: There is a pregnancy registry for women who take antipsychotic medications, such as olanzapine.  For more information you can look at their website: