Formulary
Cimetidine: Indications, Dosing, Side Effects and Interactions
Cimetidine clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 4 min read
Cimetidine: Indications, Dosing, Side Effects and Interactions
Cimetidine clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Benign duodenal ulceration**
- **Adult** (By Mouth): 400 mg twice daily for at least 4 weeks, to be taken with breakfast and at night, alternatively 800 mg once daily for at least 4 weeks, to be taken at night; increased if necessary up to 400 mg 4 times a day; maintenance 400 mg once daily, to be taken at night, alternatively maintenance 400 mg twice daily, to be taken in the morning and at night.
**Benign gastric ulceration**
- **Adult** (By Mouth): 400 mg twice daily for 6 weeks, to be taken with breakfast and at night, alternatively 800 mg daily for 6 weeks, to be taken at night; increased if necessary up to 400 mg 4 times a day; maintenance 400 mg once daily, to be taken at night, alternatively maintenance 400 mg twice daily, to be taken in the morning and at night.
**NSAID-associated ulceration**
- **Adult** (By Mouth): 400 mg twice daily for 8 weeks, to be taken with breakfast and at night, alternatively 800 mg daily for 8 weeks, to be taken at night; increased if necessary up to 400 mg 4 times a day; maintenance 400 mg daily, to be taken at night, alternatively maintenance 400 mg twice daily, to be taken in the morning and at night.
**Reflux oesophagitis**
- **Adult** (By Mouth): 400 mg 4 times a day for 4-8 weeks.
**Prophylaxis of stress ulceration**
- **Adult** (By Mouth): 200-400 mg every 4-6 hours.
**Gastric acid reduction in obstetrics**
- **Adult** (By Mouth): Initially 400 mg, to be administered at start of labour, then increased if necessary up to 400 mg every 4 hours, do not use syrup in prophylaxis of acid aspiration; maximum 2.4 g per day.
**Gastric acid reduction during surgical procedures**
- **Adult** (By Mouth): 400 mg, to be given 90-120 minutes before induction of general anaesthesia.
**Short-bowel syndrome**
- **Adult** (By Mouth): 400 mg twice daily, adjusted according to response, to be taken with breakfast and at bedtime.
**To reduce degradation of pancreatic enzyme supplements**
- **Adult** (By Mouth): 0.8-1.6 g daily in 4 divided doses, dose to be taken 1-1 hours before meals.
Cautions
For all h2-receptor antagonists Signs and symptoms of gastric cancer Cautions, further information Gastric cancer H 2 -receptor antagonists might mask symptoms of gastric cancer; particular care is required in patients presenting with 'alarm features' in such cases gastric malignancy should be ruled out before treatment.
Side effects
For all h2-receptor antagonists Common or very common Diarrhoea; dizziness; fatigue; headache; myalgia; skin reactions Uncommon Confusion; depression; erectile dysfunction; gynaecomastia; hallucination; hepatitis; leucopenia; nausea Rare or very rare Agranulocytosis; alopecia; arthralgia; atrioventricular block; fever; pancytopenia; thrombocytopenia Side-effects For cimetidine Uncommon Arrhythmias Rare or very rare Anaphylactic reaction; aplastic anaemia; galactorrhoea; hypersensitivity vasculitis; nephritis tubulointerstitial; pancreatitis
Interactions
**Other interactions (7):**
- Cimetidine can prolong the elimination of drugs metabolised by oxidation in the liver.
- Although interactions between cimetidine and a number of drugs have been demonstrated e.g.
- Close monitoring of patients on cimetidine receiving oral anticoagulations or phenytoin is recommended and a reduction in the dosage of these drugs may be necessary.
- Cimetidine has the potential to affect the absorption, metabolism or renal excretion of other drugs which is particularly important when drugs with a narrow therapeutic index are administered...
- Interactions may occur by several mechanisms including: 1) Inhibition of certain cytochrome P450 enzymes (including CYP1A2, CYP2C9, CYP2D6 and CYP3A3/A4, and CYP2C18); Inhibition of these enzymes...
- This can result in either an increase in absorption (e.g.
Pregnancy
Manufacturer advises avoid unless essential.
Breast feeding
Significant amount present in milk-not known to be harmful but manufacturer advises avoid.
Hepatic impairment
Increased risk of confusion. Dose adjustments Reduce dose.
Renal impairment
Dose adjustments Reduce dose to 200 mg 4 times a day if creatinine clearance 30-50 mL/minute. M Reduce dose to 200 mg 3 times a day if creatinine clearance 15-30 mL/minute. M Reduce dose to 200 mg twice daily if creatinine clearance less than 15 mL/minute. M See Prescribing in renal impairment .
Medicinal forms
Suspension,Tablet,Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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