Is Dimenhydrinate (Gravol) safe during pregnancy?

From the Guidelines

Gravol (dimenhydrinate) is considered safe for use during pregnancy when taken as directed for short periods, with a recommended dose of 50-100 mg every 4-6 hours as needed, not exceeding 400 mg in 24 hours. According to the American College of Obstetricians and Gynecologists (ACOG) and as discussed in the 2024 study 1, H1-receptor antagonists like doxylamine, promethazine, and dimenhydrinate are considered safe first-line pharmacologic antiemetic therapies for nausea and vomiting during pregnancy. The study also highlights the importance of diet and lifestyle modification as initial steps in managing these symptoms, including reducing spicy, fatty, acidic, and fried foods, and eating small, frequent, and bland meals.

Key Considerations

• Gravol works by blocking histamine receptors in the brain that trigger nausea and vomiting, and has been used for decades with no evidence of causing birth defects or pregnancy complications when used appropriately 1.
• It's essential to try non-medication approaches first, such as eating small, frequent meals, avoiding triggering foods, staying hydrated, and using ginger products, as recommended by the 2024 study 1.
• If nausea is severe, persistent, or accompanied by inability to keep fluids down, it's crucial to contact a healthcare provider immediately, as this may indicate hyperemesis gravidarum requiring medical attention.
• The Motherisk Pregnancy Unique Quantification of Emesis score (Table 1) can be used to quantify the severity of vomiting during pregnancy, with a maximum score of 15 and severity categorized as mild (6), moderate (7-12), or severe (13) 1.

Important Reminders

• Always follow the recommended dosage and consult a healthcare provider before taking Gravol or any other medication during pregnancy.
• Be aware of the potential side effects of Gravol, such as drowsiness and dry mouth, and take necessary precautions to minimize these effects.
• Keep in mind that while Gravol is classified as a Category B medication in pregnancy, it's always preferable to try non-medication approaches first and to use the medication only as directed and for short periods.

From the FDA Drug Label

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. There are no adequate and well-controlled studies in pregnant women However, clinical studies in pregnant women have not indicated that dimenhydrinate increases the risk of abnormalities when administered in any trimester of pregnancy. It would appear that the possibility of fetal harm is remote when the drug is used during pregnancy Nevertheless, because the studies in humans cannot rule out the possibility of harm, dimenhydrinate should be used during pregnancy only if clearly needed.

Dimenhydrinate use in pregnancy should be done with caution.

• The drug is classified as Pregnancy Category B.
• Although animal studies have shown no evidence of harm to the fetus, human studies are limited and cannot rule out the possibility of harm.
• Clinical studies in pregnant women have not indicated an increased risk of abnormalities, but dimenhydrinate should only be used during pregnancy if clearly needed 2.

From the Research

Gravol and Pregnancy

• Gravol, also known as dimenhydrinate, is an antihistamine used to treat nausea and vomiting, including those associated with pregnancy 3.
• A study comparing the effectiveness of vitamin B6 and dimenhydrinate for gestational nausea and vomiting found that both treatments significantly reduced nausea and vomiting scores, with dimenhydrinate being more effective than vitamin B6 3.
• Another study found that ginger and pyridoxine (vitamin B6) were effective in reducing the severity of nausea and vomiting in pregnancy, with ginger being more effective for nausea and distress of vomiting 4.
• The American College of Obstetricians and Gynecologists (ACOG) recommends that nausea and vomiting of pregnancy be distinguished from other causes and treated accordingly, with safe and effective treatments available for more severe cases 5.
• A systematic review of treatments for hyperemesis gravidarum and nausea and vomiting in pregnancy found that antihistamines, including dimenhydrinate, were associated with improved symptoms compared to placebo 6.

Treatment Options

• The following treatments have been found to be effective for nausea and vomiting in pregnancy:
  • Ginger 4
  • Pyridoxine (vitamin B6) 4, 3
  • Antihistamines, including dimenhydrinate (Gravol) 6, 3
  • Metoclopramide 6
  • Ondansetron 6, 7
• The choice of treatment depends on the severity of symptoms and the individual woman's preferences and medical history 5.

Safety and Efficacy

• Dimenhydrinate (Gravol) has been found to be safe and effective for treating nausea and vomiting in pregnancy, although it may have side effects such as drowsiness 3.
• Ginger and pyridoxine (vitamin B6) are generally considered safe and well-tolerated, with few side effects 4.
• Ondansetron has been found to be effective for treating nausea and vomiting in pregnancy, but its safety and efficacy are still being studied 6, 7.