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H2-receptor antagonist Pregnancy: Safety in pregnancy has not been established; animal studies showed no evidence of impaired fertility or teratogenicity. Should only be used in pregnant women, or those planning pregnancy, if considered absolutely necessary and then with caution. About 0.1% of an oral dose is secreted in human milk — administer to nursing mothers only if considered absolutely necessary.

Nizatidine

Brand names: Axid

Nizatidine is a histamine H2-receptor antagonist used to reduce gastric acid in conditions such as peptic ulcer disease and gastro-oesophageal reflux disease.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Duodenal ulcer or benign gastric ulcer: 300 mg daily, taken in the evening. If preferred, the 300 mg daily dose may be given as two divided doses of 150 mg in the morning and evening
Route: Oral
Frequency: Once daily in the evening (or 150 mg twice daily)
Max: 300 mg twice daily — the highest regimen stated in the SPC, for gastro-oesophageal reflux disease
Duodenal ulcer: continue treatment for four weeks (may be shortened if healing is confirmed earlier by endoscopy); if complete healing has not occurred after four weeks, continue for a further four weeks. Benign gastric ulcer: 300 mg daily in the evening for four or, if necessary, eight weeks — exclude the possibility of gastric cancer before treatment. Prevention of duodenal or benign gastric ulcer recurrence (prophylactic maintenance therapy): 150 mg daily in the evening. Gastro-oesophageal reflux disease: 150 mg twice daily up to 300 mg twice daily; therapy for up to 12 weeks is indicated for erosions, ulcerations and associated heartburn. Gastric and/or duodenal ulcer associated with concomitant NSAID use: 300 mg daily (either 300 mg at bedtime or 150 mg twice daily, morning and evening) for up to 8 weeks — most ulcers heal within 4 weeks and NSAIDs may be continued during treatment. Elderly: age does not significantly influence efficacy or safety and dosage modification is not normally required except in moderate to severe renal impairment (creatinine clearance less than 50 mL/min). Paediatric population: safety and efficacy in children have not been established, no data available.

Dose adjustments

Renal

Reduce the dose in moderate renal impairment (creatinine clearance less than 50 mL/min) and severe renal impairment (creatinine clearance less than 20 mL/min). Duodenal ulcer, benign gastric ulcer and NSAID-associated ulcer: 150 mg in the evening (moderate) or 150 mg on alternate days (severe). Prevention of ulcer recurrence: 150 mg in the evening on alternate days (moderate) or 150 mg in the evening every third day (severe). Gastro-oesophageal reflux disease: from 150 mg daily up to 150 mg twice daily (moderate), or from 150 mg on alternate days up to 150 mg daily (severe). Patients with impaired liver or kidney function should be treated with caution.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance, to any other H2-receptor antagonist, or to any of the excipients

Side effects

  • Sweating and urticaria (significantly more common than placebo in large-scale trials)
  • Somnolence
  • Mild, transient, asymptomatic elevations of transaminases or alkaline phosphatase; hepatitis and jaundice reported, including rare cholestatic or mixed hepatocellular and cholestatic injury
  • Rarely: thrombocytopenic purpura, fatal thrombocytopenia, leucopenia, agranulocytosis, anaemia
  • Headache and diarrhoea (frequency not known); rare hypersensitivity reactions including bronchospasm, laryngeal oedema, rash, pruritus, eosinophilia, serum sickness and anaphylaxis

Interactions

  • No effect on serum levels of concomitantly administered aminophylline, theophylline, chlordiazepoxide, diazepam, lidocaine, phenytoin, ibuprofen, metoprolol, warfarin or lorazepam; nizatidine does not inhibit the hepatic cytochrome P450 drug-metabolising enzyme system
  • Salicylates — nizatidine may increase their absorption when used in very high dosage
  • Drugs whose absorption is dependent on an acidic gastric pH — nizatidine and other H2-receptor antagonists can reduce their gastric absorption
  • Absorption of nizatidine is not clinically significantly affected by food intake, anticholinergic agents or antacids

Clinical monograph

How it works

It competitively blocks histamine H2 receptors on gastric parietal cells, reducing both basal and stimulated gastric acid secretion.

Prescribing in practice

  • Exclude gastric malignancy before treatment, as acid suppression can mask the symptoms of gastric cancer.
  • Dose adjustment is needed in renal impairment because the drug is largely renally cleared.
  • It is generally well tolerated but its acid-lowering effect can alter absorption of pH-dependent medicines.

Monitoring

Routine laboratory monitoring is not usually required, but review symptom response and renal function where relevant.

Counselling the patient

  • Advise patients to report persistent or alarm symptoms such as difficulty swallowing, weight loss or vomiting.
  • Explain that the medicine reduces stomach acid and that lifestyle measures support reflux control.

Evidence & guidelines

H2-receptor antagonists such as nizatidine are well-established acid-suppressing agents, used in line with current prescribing references and NICE dyspepsia guidance.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.