Natural Health Research

Naturopathic Medicine
Health Quizzes
Cimetidine, Tagamet


Cimetidine is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers.


H2 antagonist, decreases stomach acid


angioedema, aspiration prophylaxis, duodenal ulcer, esophagitis, gastric ulcer, gastritis, gastroesophageal reflux disease (GERD), multiple endocrine adenoma syndrome, pyrosis (heartburn), stress gastritis prophylaxis, systemic mastocytosis, upper GI bleeding, urticaria, Zollinger-Ellison syndrome,

Side Effects

Cimetidine interferes with estrogen metabolism, enhancing estrogen activity. This can lead to gynecomastia.

acneiform rash, agitation, agranulocytosis, depression, diarrhea, elevated hepatic enzymes, exfoliative dermatitis, galactorrhea, gynecomastia, hallucinations, headache, hepatitis, impotence, jaundice, leukopenia, libido decrease, maculopapular rash, neutropenia, pancreatitis, pancytopenia, Stevens-Johnson syndrome, thrombocytopenia, toxic epidermal necrolysis, urticaria, vasculitis,

Drug-Vitamin-Herb Interactions

Negative interactions:

Magnesium (often found in antacids) may reduce the absorption of H2 antagonists. Take at a different time of day.

Positive interactions:

Folate absorption is best in an acidic environment. H2 antagonists reduce stomach acid which can lower folate absorption.

Vitamin B12
Vitamin B12 absorption may be impaired by H2 antagonists, which reduce stomach acid.

Iron and Zinc
Iron and Zinc absorption is inhibited by reduced stomach acid levels.

Vitamin D
Cimetidine may interfere with vitamin D metabolism.




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