This sheet talks about exposure to OnabotulinumtoxinA in a pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is onabotulinumtoxinA?

OnabotulinumtoxinA (formerly called botulinum toxin type A) is injected into the skin or muscle to treat migraine headaches, excessive sweating, muscle spasms or stiffness, eye muscle conditions (such as crossed eyes, eyelid twitching), and urinary leakage. It is also used cosmetically to reduce the look of wrinkles. Some brand names include Botox® or Botox Cosmetic®.

What is the difference between onabotulinumtoxinA and botulism?

OnabotulinumtoxinA is a germ-free medical treatment made from the purified toxin of a bacterium called Clostridium botulinum. Clostridium botulinum can cause a rare illness called botulism. People get botulism  most commonly by eating food contaminated with Clostridium botulinum. Botulism bacteria is most common in foods that are not properly preserved, like home canned foods, fermented foods (i.e. sauerkraut and pickled foods), or dented canned foods. The bacteria are killed by heating foods for longer than 5 minutes at greater than 185°F (85°C). People with botulism can have weakness, vision problems, difficulty swallowing, dry mouth, breathing problems, and trouble speaking. In some cases, it can be fatal. Botulism is not contagious.

Does onabotulinumtoxinA get into my bloodstream or cross the placenta?

Studies have shown that when injected properly and at the right dose, onabotulinumtoxinA does not usually enter the bloodstream. If it is not in a mother’s bloodstream, it cannot cross the placenta. Even if onabotulinumtoxinA did reach the mother’s blood stream, the toxin molecule is large and is therefore unlikely to cross the placenta and reach the baby.

Can having onabotulinumtoxinA treatments make it more difficult to get pregnant?

There are no published studies on onabotulinumtoxinA use during pregnancy. Because it does not appear to get into the bloodstream, it is not expected to affect fertility.

Can using onabotulinumtoxinA during pregnancy increase the chance for miscarriage?                       Miscarriage can occur in any pregnancy. There are no published studies on OnabotulinumtoxinA use and miscarriage. Because it does not appear to get into the bloodstream, it is not expected to increase the chance for miscarriage.

Can using onabotulinumtoxinA treatments during pregnancy increase the chance for birth defects?

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. There are no published studies on onabotulinumtoxinA use during pregnancy and other reports are limited. A report from the manufacturer, which included 137 pregnancies exposed either during pregnancy or a few months before getting pregnant, did not find a pattern of birth defects or an increased chance of birth defects.

Can I have onabotulinumtoxinA treatments while breastfeeding?

No studies on breastfeeding while using onabotulinumtoxinA are available. However, because onabotulinumtoxinA injections are not thought to get into the bloodstream, it would be unlikely to be able to enter the breast milk. Therefore, the risk to an infant is thought to be very low. Be sure to talk to your healthcare provider about all your breastfeeding questions.

If a man takes onabotulinumtoxinA, could it affect his fertility (ability to get partner pregnant) or increase the chance of birth defects? 

This has not been well studied. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at

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