Proton Pump Inhibitor (PPI) Pregnancy: Use with caution — animal data reassuring but limited human data; use if benefit outweighs risk

Omeprazole

Brand names: Losec

Adult dose

Dose: 20–40 mg

Route: Oral / IV

Frequency: Once daily

Max: 120 mg/day (Zollinger-Ellison syndrome)

GORD/peptic ulcer: 20 mg once daily for 4–8 weeks. H. pylori eradication: 20 mg BD with antibiotics for 7 days. IV for patients unable to take oral. Take 30–60 minutes before food.

Paediatric dose

Dose: 0.7–1.4 mg/kg

Route: Oral

Frequency: Once daily

Max: 20 mg/day (under 20 kg); 40 mg/day (over 20 kg)

GORD in children ≥1 year: 0.7–1.4 mg/kg once daily.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

Severe hepatic impairment: max 20 mg/day.

Paediatric weight-based calculator

Patient weight (kg)

GORD in children ≥1 year: 0.7–1.4 mg/kg once daily.

Clinical pearls

MHRA: long-term PPI use linked to hypomagnesaemia — check Mg if on long-term therapy
Prefer pantoprazole over omeprazole in patients on clopidogrel (less CYP2C19 inhibition)
Review PPI need regularly — widespread overprescribing noted; deprescribe when no longer indicated
IV omeprazole used for Rockall score ≥3 upper GI bleeds post-endoscopy

Contraindications

Concomitant atazanavir or nelfinavir (reduces antiviral absorption)

Side effects

Headache
Nausea
Diarrhoea
Hypomagnesaemia (long-term use)
C. difficile risk (long-term)
Hyponatraemia
Osteoporosis (long-term)
Fundic gland polyps (benign)

Interactions

Clopidogrel (omeprazole reduces antiplatelet effect — use pantoprazole instead)
Methotrexate (PPIs may increase toxicity)
Atazanavir/nelfinavir (avoid concomitant use)
Warfarin (may increase INR)

Monitoring

Serum magnesium (long-term use)
Review indication annually

Reference: BNFc; BNF 90; NICE NG184 (Gastro-oesophageal Reflux Disease); MHRA Drug Safety Update (Hypomagnesaemia). Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

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