About cimetidine
Histamine H2-receptor blocker
Used for
- Treats stomach and intestinal ulcers
- Relieves heartburn and acid indigestion
- Treats reflux symptoms
- Reduces stomach acid in certain conditions
Usual adult dose
Commonly 400 mg twice daily or 800 mg at bedtime for ulcers; dosing varies by condition.
Usual dose in children
For children, dosing is weight-based and condition-specific; use requires clinician guidance.
Common side effects
- Headache
- Diarrhea
- Dizziness
- Confusion, especially in older adults
Important warnings
- Kidney problems may require a lower dose.
- Seek assessment for trouble swallowing, vomiting blood, or unexplained weight loss.
- Long-term use may cause vitamin B12 deficiency.
- Rarely, confusion or abnormal heart rhythm can occur.
Pregnancy
Use only when needed and after discussing benefits and risks with a healthcare professional.
Breastfeeding
Small amounts enter breast milk; discuss use with a healthcare professional, especially for prolonged treatment.
Interactions
- Can increase warfarin effects and bleeding risk.
- May raise levels of phenytoin, theophylline, and some sedatives.
- Antacids can reduce absorption if taken together.
- May interact with medicines affected by 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 It may be incomplete or out of date.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.