Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Proton Pump Inhibitor (PPI)

Omeprazole

Brand names: Losec

Used in: Gastrointestinal Bleeding

Omeprazole is a proton pump inhibitor used to treat gastro-oesophageal reflux disease, peptic ulcer disease, as part of Helicobacter pylori eradication, and for gastroprotection in patients taking NSAIDs.

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

  • It can mask the symptoms of gastric cancer, so investigate alarm features such as unexplained weight loss, dysphagia or gastrointestinal bleeding before attributing them to reflux.
  • It reduces the antiplatelet effect of clopidogrel and may lower magnesium with long-term use, so review the indication and duration periodically.
  • Prolonged use is associated with increased risk of fractures and gastrointestinal infections, so use the lowest effective dose for the shortest necessary period.

Monitoring

Review the ongoing need for treatment regularly, and consider checking magnesium with long-term use or when combined with other magnesium-lowering drugs.

Counselling the patient

  • Take it before food, usually in the morning, for best effect.
  • Tell your doctor if you develop difficulty swallowing, weight loss or black stools.
  • Do not stop or continue long term without review, as long-term use carries some risks.

Evidence & guidelines

Proton pump inhibitors including omeprazole are first-line acid-suppression therapy in NICE dyspepsia and gastro-oesophageal reflux guidance.

Reference: NICE NG184 (Gastro-oesophageal Reflux Disease); MHRA Drug Safety Update (Hypomagnesaemia); 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.

Calculators
Drugs
Pathways