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Proton Pump Inhibitor — Obstetric

Omeprazole (GORD / Hyperemesis in Pregnancy)

Brand names: Losec, Prilosec

Omeprazole is a proton pump inhibitor used in pregnancy to treat gastro-oesophageal reflux disease and acid-related symptoms, and as adjunctive acid suppression in hyperemesis gravidarum.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It irreversibly inhibits the gastric H+/K+-ATPase (proton pump) in parietal cells, markedly reducing basal and stimulated gastric acid secretion.

Prescribing in practice

  • Omeprazole has a reassuring safety record in pregnancy and is used when lifestyle measures and antacids or alginates are insufficient.
  • It may mask the symptoms of, and rarely delay diagnosis of, underlying gastric malignancy, so alarm features warrant investigation.
  • It interacts with several drugs, notably reducing the activation of clopidogrel and affecting agents whose absorption depends on gastric acidity.

Monitoring

Routine monitoring is not usually required; review symptom control and consider magnesium and B12 with prolonged use.

Counselling the patient

  • Take it before food, typically in the morning.
  • Continue lifestyle measures such as smaller meals and avoiding late eating.
  • Report difficulty swallowing, vomiting blood or unintended weight loss.

Evidence & guidelines

Proton pump inhibitors including omeprazole are recommended where simpler measures fail for reflux in pregnancy, supported by reassuring observational safety data.

Reference: RCOG Green-top 69 (Hyperemesis Gravidarum 2024); NICE NG201; Pasternak & Hviid (2010) Danish cohort; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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