What medications are recommended for managing vomiting in pregnancy?

Medications for Vomiting in Pregnancy

Start with the combination of doxylamine 10 mg and pyridoxine (vitamin B6) 10 mg as first-line pharmacologic treatment for nausea and vomiting in pregnancy—this is the only FDA-approved medication specifically for this indication and carries Pregnancy Category A status. 1, 2

Stepwise Treatment Algorithm

Mild Symptoms (PUQE Score ≤6)

Non-pharmacologic interventions:

• Small, frequent, bland meals (BRAT diet: bananas, rice, applesauce, toast) with high-protein, low-fat content 1
• Avoid spicy, fatty, acidic, and fried foods 1

Initial supplements if dietary changes insufficient:

• Ginger 250 mg capsules four times daily 1
• Vitamin B6 (pyridoxine) 10-25 mg every 8 hours 1

Moderate Symptoms (PUQE Score 7-12)

First-line pharmacologic treatment:

• Doxylamine-pyridoxine combination (Diclegis): 10 mg/10 mg tablets, starting with 2 tablets at bedtime, increasing up to 4 tablets daily (1 morning, 1 afternoon, 2 bedtime) as needed 1, 3, 2
• This combination is safe throughout pregnancy and breastfeeding 3

Alternative H1-receptor antagonists if doxylamine unavailable:

• Promethazine 1, 3
• Dimenhydrinate 1
• Cyclizine 3

Severe Symptoms or Hyperemesis Gravidarum (PUQE Score ≥13)

Second-line agents when first-line fails:

• Metoclopramide: preferred second-line agent with less drowsiness and fewer side effects than promethazine 3
• Ondansetron (5-HT3 antagonist): reserve as second-line, use cautiously before 10 weeks gestation due to small risk of congenital heart defects 1, 3
• Both metoclopramide and ondansetron are compatible throughout pregnancy and breastfeeding 3

Third-line therapy for refractory cases:

• Methylprednisolone: 16 mg IV every 8 hours for up to 3 days, then taper over 2 weeks to lowest effective dose (maximum 6 weeks) 3
• Avoid corticosteroids before 10 weeks gestation due to slight increased risk of cleft palate 3

Critical Supportive Care for Severe Cases

Immediate interventions for hyperemesis gravidarum:

• Intravenous fluid resuscitation and electrolyte replacement (particularly potassium and magnesium) 1, 3
• Thiamine 200-300 mg IV daily for at least 3-5 days to prevent Wernicke's encephalopathy—pregnancy depletes thiamine stores within 7-8 weeks of persistent vomiting 3
• Check liver function tests (50% will have abnormal AST/ALT, though rarely >1,000 U/L) 3

Important Clinical Caveats

Timing and progression:

• Early intervention is crucial to prevent progression from mild nausea to hyperemesis gravidarum 1, 3
• Symptoms typically begin at 4-6 weeks, peak at 8-12 weeks, and resolve by week 20 in 80% of women 1, 3

Safety monitoring:

• Withdraw phenothiazines or metoclopramide immediately if extrapyramidal symptoms develop 3
• Monitor QT interval with ondansetron, especially with electrolyte abnormalities 3
• No significant efficacy difference exists among metoclopramide, ondansetron, and promethazine based on meta-analysis 3

Red flags requiring further investigation:

• Weight loss >5% of prepregnancy weight indicates hyperemesis gravidarum 1, 3
• Persistent liver chemistry abnormalities despite symptom resolution warrant investigation for alternative etiology 3
• Multidisciplinary care (obstetricians, gastroenterologists, nutritionists) may be necessary for severe refractory cases 3