About cimetidine
Histamine-2 receptor blocker
Used for
- Treats stomach and duodenal ulcers
- Treats gastroesophageal reflux and erosive esophagitis
- Reduces stomach acid in conditions causing excessive acid production
Usual adult dose
Common injection dosing is 300 mg every 6–8 hours; dosing varies by condition and kidney function.
Usual dose in children
For children over 1 year, dosing is usually 20–40 mg/kg daily in divided doses; specialist guidance is needed.
Common side effects
- Diarrhea
- Headache
- Dizziness
- Confusion, especially in older adults or with kidney impairment
Important warnings
- Dose adjustment may be needed with kidney impairment.
- Rarely, it can affect blood counts or cause liver problems.
- It may mask symptoms of stomach cancer.
- Use by injection requires healthcare professional supervision.
Pregnancy
Use only when needed and prescribed; discuss potential benefits and risks with a healthcare professional.
Breastfeeding
Cimetidine enters breast milk and may affect the infant; alternatives may be preferred.
Interactions
- Can increase warfarin effects and bleeding risk.
- May raise levels of medicines such as phenytoin, theophylline, and lidocaine.
- Antacids may reduce absorption of oral cimetidine.
- Can affect medicines whose absorption depends on stomach acidity.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.