Proton Pump Inhibitor — Obstetric Pregnancy: Safe in pregnancy — extensive safety data; preferred PPI in pregnancy

Omeprazole (GORD / Hyperemesis in Pregnancy)

Brand names: Losec, Prilosec

Adult dose

Dose: 20-40 mg once daily

Route: Oral / Intravenous

Frequency: Once daily (morning before food)

Max: 40 mg/day

GORD in pregnancy: 20 mg once daily (antacids and lifestyle first; PPI if inadequate response). Hyperemesis Gravidarum: 20-40 mg once daily (step-up treatment). RCOG Green-top 69 (2024): PPIs recommended in HG

Paediatric dose

Dose: Not applicable in this obstetric context N/A/kg

Route: Oral

Frequency: N/A

Max: N/A

Maternal medication

Dose adjustments

Renal

No dose adjustment required

Hepatic

Reduce to 20 mg/day max in severe hepatic impairment

Paediatric weight-based calculator

Patient weight (kg)

Maternal medication

Clinical pearls

GORD in pregnancy: very common due to progesterone-mediated lower oesophageal sphincter relaxation and mechanical displacement of stomach — affects 50-80% of pregnant women in third trimester
RCOG Green-top 69 (2024): Omeprazole recommended in step-up HG management — for oesophagitis, reflux, and as adjunct in NVP with co-existing acid symptoms
Safety in pregnancy: large cohort studies (over 150,000 pregnancies) show no increased risk of major congenital malformations — considered safe throughout pregnancy
Magnesium monitoring: hypomagnesaemia with prolonged PPI use may complicate hyperemesis (already at risk of electrolyte disturbances); supplement if needed
Rebound acid hypersecretion on stopping: wean off gradually after prolonged use — abrupt withdrawal causes worse acid symptoms than baseline

Contraindications

Hypersensitivity to omeprazole or other PPIs
Concurrent rilpivirine use

Side effects

Headache
Nausea
Diarrhoea or constipation
Hypomagnesaemia (prolonged use)
C. difficile (marginally increased risk with long-term use)
Hypergastrinaemia (rebound acid hypersecretion on stopping)

Interactions

Clopidogrel (CYP2C19 inhibition reduces clopidogrel activation — use pantoprazole instead)
Methotrexate (PPIs increase methotrexate levels)
Atazanavir / rilpivirine (reduced absorption with raised gastric pH)

Monitoring

Symptom response
Magnesium (prolonged use)
Vitamin B12 (long-term use)

Reference: BNFc; BNF 90; RCOG Green-top 69 (Hyperemesis Gravidarum 2024); NICE NG201; Pasternak & Hviid (2010) Danish cohort. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators