From the Guidelines
For managing nausea and vomiting in pregnancy, first-line treatment includes vitamin B6 (pyridoxine) 10-25 mg three to four times daily, which can be combined with doxylamine 12.5 mg (available as Diclegis or Bonjesta in a combination tablet, or separately as over-the-counter Unisom) 1. If these are insufficient, phenothiazines like promethazine (12.5-25 mg every 4-6 hours) or prochlorperazine (5-10 mg every 6-8 hours) can be used. For more severe cases, ondansetron (4-8 mg every 8 hours) is often effective, though it should be used with caution in the first trimester due to a small potential risk of cleft palate 1. Metoclopramide (5-10 mg three times daily) is another option with good safety data. Some key points to consider when managing nausea and vomiting in pregnancy include:
- Non-pharmacological approaches like eating small, frequent meals, avoiding triggers, and ginger supplements (250 mg four times daily) should be tried first or used alongside medications 1.
- For hyperemesis gravidarum, intravenous hydration and antiemetics may be necessary, sometimes including methylprednisolone 1.
- These medications are generally considered safe in pregnancy when benefits outweigh risks, as untreated severe nausea and vomiting can lead to dehydration, electrolyte imbalances, and weight loss that may harm both mother and fetus 1. It's essential to weigh the benefits and risks of each medication and consider the severity of the symptoms when deciding on a treatment plan. Some medications, such as ondansetron, may have a small potential risk of cleft palate, but the absolute risk is still relatively low 1. Ultimately, the goal is to manage symptoms effectively while minimizing risks to the mother and fetus.
From the FDA Drug Label
8 USE IN SPECIFIC POPULATIONS
8.1 Pregnancy Risk Summary Published epidemiological studies on the association between ondansetron use and major birth defects have reported inconsistent findings and have important methodological limitations that preclude conclusions about the safety of ondansetron use in pregnancy
Pregnancy Category B Reproduction studies have been performed in rats at doses up to 20 times the human dose, and in rabbits at doses up to 25 times the human dose (on a mg/kg basis), and have revealed no evidence of impaired fertility or harm to the fetus due to dimenhydrinate.
The antiemetics that can be considered in pregnancy are:
- Ondansetron: Although the data is inconsistent, it may be used in pregnancy, but with caution and only if clearly needed 2.
- Dimenhydrinate: It is classified as Pregnancy Category B, and clinical studies in pregnant women have not indicated that dimenhydrinate increases the risk of abnormalities when administered in any trimester of pregnancy, but it should be used during pregnancy only if clearly needed 3.
From the Research
Antiemetics for Pregnancy
The following antiemetics are recommended for use in pregnancy:
- Ginger, vitamin B6, antihistamines, and metoclopramide for mild symptoms 4
- Pyridoxine-doxylamine, promethazine, and metoclopramide for moderate symptoms 4
- Ondansetron for a range of symptom severity 4, 5
- Corticosteroids for severe cases 4, 6
First-Line Treatment
The combination of doxylamine succinate/pyridoxine hydrochloride is recommended as first-line pharmacologic treatment for nausea and vomiting in pregnancy 6
Second-Line Treatment
Ondansetron and metoclopramide may be used as second-line antiemetics in women with nausea and vomiting in pregnancy 5
Important Considerations
- Nausea and vomiting of pregnancy should be distinguished from nausea and vomiting related to other causes 7, 8
- The woman's perception of the severity of her symptoms plays a critical role in the decision of whether, when, and how to treat nausea and vomiting of pregnancy 7, 8
- Treatment in the early stages may prevent more serious complications, including hospitalization 7, 8