What is Ondansetron?
Ondansetron is a tablet that’s used off-label to treat morning sickness. This just means that while it’s proven to be a safe and effective treatment, it isn’t officially licensed to treat morning sickness.
Hormonal changes during pregnancy can make you feel nauseous or cause you to be sick, especially in the mornings. Ondansetron blocks receptors in your brain and gut involved in nausea and vomiting reflexes to help reduce these symptoms.
Who can use Ondansetron?
Ondansetron is suitable for most women in their second or third trimester of pregnancy to use. It’s usually not recommended during the first trimester because there’s some evidence that Ondanestron could increase the risk of a baby being born with a cleft lip or palate when used during this time.[1]
What are the benefits of Ondansetron?
One benefit of Ondansetron over other similar anti-sickness tablets is that it may come with a lower risk of side effects. In a study comparing Ondansetron to Metoclopramide, another anti-sickness tablet, Ondansetron was found to have no side effects – while the Metoclopramide group reported side effects of weakness and difficulty remaining still.[2]
How do Ondansetron doses work?
Ondansetron comes in two different doses: 4 mg and 8 mg tablets. Depending on how severe your morning sickness is, you’ll take 4-8 mg of Ondansetron every 6-8 hours as needed, up to three times daily. You can take Ondansetron for up to 5 consecutive days.
What is Ondansetron’s active ingredient?
Ondasetron is a generic medication that’s named after its active ingredient: ondansetron. It’s a type of 5-HT3 serotonin receptor agonist, and is similar to other anti-sickness medicines like granisetron, dolasetron, and palonosetron.
How does Ondansetron work?
Ondansetron is a type of 5-HT3 serotonin-receptor antagonist, which means it targets serotonin receptors in your brain and gut. These receptors are found in the area of the brain that senses neurotransmitters like serotonin, and this area is responsible for mediating sensations of nausea and the need to vomit.
By blocking the serotonin receptors in this part of the brain as well as your GI (gastrointestinal) tract, Ondansetron interferes with the signals that make you feel nauseous and sick, which should help reduce your morning sickness symptoms.[3]
Treated trusted source:
- Huybrchts, K.F. et al. (2018). Association of maternal first trimester ondansetron use with cardiac malformations and oral clefts in offspring. JAMA. 320(23). pp. 2429-2437.
- Afacan, M. A. Tayfur, I. (2019). Comparison of the Effects of Metoclopramide and Ondansetron on Emergency Service Observation Times in Acute Gastroenteritis-Related Nausea and Vomiting Cases. The Medical Bulletin of Sisli Etfal Hospital. 53(2). pp. 186-189.
- Griddine, A. Bush, J.S. (2023). Ondansetron. StatPearls. Treasure Island (FL): StatPearls Publishing.
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