Is meclizine safe during pregnancy?

What does the evidence say about meclizine during pregnancy?

1. Most studies do not suggest an increase in birth defects with meclizine use during the first trimester, and one study of over 16,000 pregnancies exposed in the first trimester found no increased chance of preterm birth, low birth weight, short body length, or small head circumference. 1
2. Meclizine sits alongside a common problem: about 8 out of 10 pregnant people have nausea and vomiting, starting between 4 and 9 weeks and peaking between 7 and 12, and the guidance is to speak with a provider once it affects your ability to eat, drink, sleep or get through the day. 2
3. Meclizine is a first-generation antihistamine, a non-selective H1 antagonist with central anticholinergic actions that reduces vestibular incitation and labyrinth excitability. Onset is about 1 hour after an oral dose, peak around 3 hours, half-life about 6 hours, and duration approximately 8 to 24 hours. 3
4. Standard adult dosing is 25 to 50 mg orally taken 1 hour before embarking for motion sickness, 25 to 100 mg daily for vertigo, and 12.5 to 25 mg every 8 hours for Meniere disease. Common adverse effects include drowsiness, urinary retention, dry mouth, headache, fatigue, and vomiting. 3
5. Occasional doses of meclizine are probably acceptable during breastfeeding, while large doses or more prolonged use may cause effects in the infant or decrease milk supply, particularly in combination with a sympathomimetic such as pseudoephedrine or before lactation is well established. 4

Is meclizine safe in each trimester?

• First trimester. This is where the data is strongest, which is unusual. The large study that anchors the safety picture looked specifically at over 16,000 pregnancies exposed to meclizine in the first trimester and found no increased chance of birth defects, preterm birth, low birth weight, short body length, or small head circumference.
• Second trimester. Motion sickness and vertigo do not respect trimesters, and meclizine is used for both. Onset is about 1 hour after an oral dose and duration runs roughly 8 to 24 hours, so a single morning dose usually covers a travel day.
• Third trimester. Drowsiness is the practical limiter now. The half-life is about 6 hours and sedation is the most common adverse effect, which matters if you are driving or working. Dose timing is worth planning with your provider rather than improvising.

Meclizine at a glance