Ondansetron: is it safe to treat motion sickness in pregnancy?

Nausea and vomiting during pregnancy are quite common, especially during the first 3 (three) months, due to hormonal action.

In general, they do not indicate any serious or worrying situation, being only a response of the organism to the changes caused by fertilization.

However, some cases can be more intense, making it difficult for the mother to feed and even disrupting daily activities. In such cases, it may be prescribed by the obstetrician to use an antiemetic medication (acts against nausea) to alleviate the malaise.

An example of this type of medication is ondansetron, the most prescribed molecule in the United States for nausea and vomiting during pregnancy, according to the journal Pharmacoepidemiology and Drug Safety.

Better understand what this medicine is for and whether (or not) it is a safe alternative for cases of nausea in pregnancy:

Can Ondansetron be used to treat motion sickness in pregnancy?

Yes. Ondansetron is an antiemetic medication, that is, it has the main objective of preventing nausea and can be used by children (over 2 years) and adults.

According to the information on the package insert, the medication is mainly indicated to prevent and treat nausea and vomiting. However, it should be noted that when it comes to use during pregnancy, the package insert reinforces that medical guidance, prescription and follow-up are indispensable – in order to avoid any possible risk to the baby’s integrity.

New post

In January 2021, FEBRASGO (Brazilian Federation of Associations of Gynecology and Obstetrics) published a new protocol regarding gestational nausea, where ondansetron was recommended as a safe medicine for the treatment of motion sickness when accompanied by a specialist.

In this protocol, it is highlighted that ondansetron, when compared to other pharmacological groups, presents superiority of action and low incidence of side effects to pregnant women.

In the same document, FEBRASGO also concludes that this medication cannot be considered an important teratogen (agents capable of causing damage to the embryo).

These analyzes are of paramount importance, considering that in 2019 some preliminary studies without great foundation were published, associating the use of ondansetron in pregnancy as a risk factor for the development of cleft lip and palate (cleft lip) in the fetus.

In some cases, the pregnant woman needs to take medication to relieve nausea. However, this should only be done under medical prescription, in order to preserve the health of the mother and baby.

In reality, they were studies that presented analog errors and computed data, but not controlled on the actual use of the medication or the period used. The author himself later publishes another study, this time with greater rigor in the control of use and period, including injectable form, with no evidence of a teratogenic effect on the fetus. These data are associated with the countless other publications demonstrating the guarantee of the use of ondansetron in the first trimester of pregnancy.

Thus, the new FEBRASGO note reinforces the safety of this medication and demystifies its use, showing that in addition to being effective in itself, it does not pose a risk to fetal development. This, considering a treatment carried out with the accompaniment of a (a) doctor (a) specialist.

How does ondansetron act in the body?

Ondansetron acts on serotonin 5-HT³ receptors , located in cells specialized in the gastrointestinal tract and also in the chemoreceptor trigger zone (ZGQ), which has a relevant action in inducing nausea and vomiting.

Thus, when in contact with the organism, the drug acts by blocking the receptors and inhibiting the symptoms.

Why do pregnant women have motion sickness?

It is not known exactly what is the cause of motion sickness during pregnancy. However, there are several studies that indicate the possibility of hormones (estrogen, progesterone and HCG) and their changes are related to this discomfort.

Thus, as the woman’s body is not yet used to high levels of hormones, nausea can be an adaptation response to changes.

In another line of research, there are scientists who believe that nausea is related to a defense mechanism of the maternal body.

However, although there are many studies, none yet has 100% accurate answers.

What are the risks of seasickness during pregnancy?

If nausea is frequent (more than once a day) and intense during pregnancy, they may pose risks to the health and well-being of the mother and baby. When the patient has severe vomiting, they promote dehydration, loss of mineral salts, as well as metabolic and nutritional changes.

These extreme cases are characterized as hyperemesis (uncontrollable nausea). Thus, the pregnant woman has a drop in general well-being, difficulty in doing daily activities and, mainly, eating, causing weakness, dizziness , weight loss, dehydration and even malnutrition, requiring hospitalization.

Bad formation

Such complications, then, can affect the fetus, increasing the chances of malformation, neurological complications or underweight, considering the mother’s poor health – insufficient to give the baby everything it needs to develop.

But for moderate conditions, even if accompanied by vomiting, the effects for the child are little known and, in general, there are no aggravating factors for fetal development.

It is also necessary to emphasize that, regardless of the severity of the situation, with the guidance of the obstetrician and the appropriate treatment during pregnancy, the discomfort tends to decrease and no harm to the baby should be caused.

Therefore, always count on the help of the specialist for greater safety during pregnancy.

Types of treatment for motion sickness

Basically, there are two types of treatment for gestational seasickness: one that does not involve the use of medications (alternative therapies, care with food, etc.) and one that is based on the administration of certain medications. Understand better:

Non-medicated care

Non-medicated care includes nutritional guidelines for pregnant women, emotional care and some alternative therapies (such as acupuncture, aromatherapy, etc.).

When it comes to nutritional care, the responsible professional may ask the pregnant woman to prioritize light and fractional meals, easy to digest and preferably natural. Still, care can be indicated regarding eating habits, such as respecting the interval between meals and taking care of the amount of food eaten.

Emotional aspect

As for the emotional aspect, it is often necessary for the woman to have psychological counseling during pregnancy. This, considering that anxiety and other emotions can be intense and difficult to deal with at this time, which can cause physical changes – such as nausea and vomiting.

In addition, it is worth noting that the emotional support of friends and family is also of paramount importance at this time, since it contributes to the well-being of the pregnant woman.

Drug therapy

Source: Series guidelines and recommendations (FEBRASGO) – Emesis of pregnancy

The use of medications for the treatment of nausea and vomiting associated with pregnancy is usually only prescribed by the obstetrician when these symptoms persist or are very intense.

In that case, the use of remedies such as Ondansetron may be prescribed. Thus, in general, all medications approved for use during pregnancy and which have antiemetic action (fighting nausea) can be classified as a class B therapy.

This means that they are safe drugs, but that they can present a certain degree of risk to pregnancy according to the table above. Therefore, it is reinforced that regardless of the instructions on the package insert and the approval of the medication administration in pregnant women, professional guidance is essential . Thus, safety to the health of the mother and, especially, the baby.

Whether it is mild or more intense seasickness, it is worth remembering that the ideal is always to seek medical advice, ensuring the health of the pregnant woman and the baby.

And, when necessary, safe treatments with proven efficacy can be performed, such as the use of ondansetron (in cases of severe nausea) or alternative care, aiming at the well-being of the pregnant woman.