Recommended Antiemetics at 14 Weeks Gestation
Start with first-line antiemetics: H1-antihistamines (cyclizine 50mg every 8 hours or promethazine 12.5-25mg every 4-8 hours), phenothiazines (prochlorperazine 5-10mg every 6-8 hours), or doxylamine/pyridoxine combination (20/20mg at night, escalating to three times daily if needed). 1
Treatment Algorithm
First-Line Options (Start Here)
The 2024 RCOG guideline provides Grade A evidence for these initial choices 1:
- Cyclizine: 50mg orally, IM, or IV every 8 hours
- Promethazine: 12.5-25mg every 4-8 hours (oral, IM, or IV)
- Prochlorperazine: 5-10mg every 6-8 hours orally (or 3mg buccal); 12.5mg every 8 hours IM/IV
- Doxylamine/Pyridoxine (Xonvea®): 20/20mg at bedtime, increase to additional 10/10mg in morning and 10/10mg at lunchtime if symptoms persist
- Chlorpromazine: 10-25mg every 4-6 hours (oral, IM, or IV)
These medications have robust safety and efficacy data and should be your initial prescription 1. At 14 weeks gestation, you're still within the window where nausea and vomiting of pregnancy commonly persists (up to 20% of women have symptoms beyond 16 weeks) 2.
Second-Line Options (If First-Line Fails)
If first-line antiemetics are ineffective, escalate to:
Ondansetron: 4mg every 8 hours or 8mg every 12 hours orally; 8mg IV over 15 minutes every 12 hours 1
- The guideline explicitly states its use "should not be discouraged" if first-line agents fail (Grade B evidence) 1
- While there is a very small absolute increase in orofacial clefting risk with first-trimester use, this must be balanced against risks of poorly managed hyperemesis gravidarum 1
- At 14 weeks, you're past the critical period for orofacial development, making this concern less relevant
- Important caveat: Women may require laxatives as constipation is common with ondansetron 1
Metoclopramide: 5-10mg every 8 hours (oral, IV, IM, or SC) 1
Domperidone: 10mg every 8 hours orally; 30mg every 12 hours rectally 1
Combination Therapy
If monotherapy fails, combine different drug classes rather than increasing doses of a single agent 1. The guideline explicitly recommends combinations for women who don't respond to single antiemetics 1.
Third-Line Options (Severe/Refractory Cases)
For severe hyperemesis gravidarum unresponsive to standard therapy:
- Corticosteroids: Hydrocortisone 100mg IV twice daily, then convert to prednisolone 40-50mg daily orally once improved, tapering by 5-10mg weekly 1
Key Clinical Considerations
Before prescribing, always ask about previous adverse reactions to antiemetics and stop medications promptly if adverse effects occur 1.
Assess severity using validated tools: The PUQE-24 score classifies symptoms as mild (≤6), moderate (7-12), or severe (13-15) 1. This helps guide treatment intensity.
Common pitfall: Don't use ketonuria to assess dehydration severity—it's not a reliable indicator (Grade A evidence) 1.
Supporting Evidence Quality
The recommendations are based on the 2024 RCOG Green-Top Guideline No. 69, endorsed by multiple UK medical organizations including the Royal College of Emergency Medicine and Royal College of General Practitioners 1. This represents the most current, high-quality guideline evidence available. The systematic review evidence from JAMA 2016 supports these recommendations, showing ginger, vitamin B6, antihistamines, and metoclopramide improve mild symptoms, while pyridoxine-doxylamine, promethazine, and metoclopramide benefit moderate symptoms 3.
The stepwise approach prioritizes medications with the strongest safety profiles first, escalating only when necessary to balance maternal quality of life against minimal fetal risks.