cimetidine vs ranitidine
Side-by-side comparison of cimetidine and ranitidine Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Tagamet
Zantac
Cimetidine (Tagamet) reduces stomach acid. It is used to treat ulcers, heartburn, and other conditions where too much acid is produced.
Ranitidine (Zantac) helps reduce stomach acid. It can relieve heartburn and sour stomach.
Cimetidine treats active duodenal ulcers for short periods. It can also be used long-term at a lower dose to prevent ulcers from returning. This medicine also treats active benign gastric ulcers for a short time. Additionally, it can help with erosive gastroesophageal reflux disease (GERD), which damages the esophagus.
This medicine treats heartburn caused by acid indigestion and sour stomach. You can also take it to prevent heartburn. It can prevent heartburn caused by eating or drinking certain foods and drinks.
Cimetidine is an H2 receptor antagonist. This means it blocks histamine from attaching to certain cells in your stomach. By blocking histamine, cimetidine reduces the amount of acid your stomach makes.
Ranitidine is an H2 receptor antagonist. It works by blocking histamine. Blocking histamine reduces the amount of acid your stomach makes.
- • Headache
- • Dizziness
- • Diarrhea
- • Headache
- Long-term kidney disease 1,264
- Sudden kidney damage 710
- Kidney failure 694
- Feeling sick to your stomach 681
- Feeling tired 599
- Breast cancer 24,853
- Prostate cancer 22,252
- Colon and rectal cancer 17,674
- Bladder cancer 16,746
- Kidney cancer 16,278
Reversible confusional states (like mental confusion, agitation, or hallucinations) have been reported, mostly in severely ill patients. These usually appear within 2-3 days of starting treatment and clear up within 3-4 days of stopping the drug.
There are no boxed warnings in the provided data.
Tell your doctor if you are pregnant or plan to become pregnant. The effects of cimetidine during pregnancy are not fully known. Talk to your doctor about the risks and benefits of taking cimetidine while breastfeeding.
There is no information about pregnancy or breastfeeding in the provided data. Talk to your doctor if you are pregnant or breastfeeding.
Also Compare — Nearby Drugs
Compare cimetidine with
Compare ranitidine with
How to Read This cimetidine vs ranitidine Comparison
cimetidine is classified in the H2 Receptor Antagonist drug class, while ranitidine sits within the H2 Receptor Antagonist class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are available over the counter.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, cimetidine has 3,948 submissions while ranitidine has 97,803. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between cimetidine and ranitidine — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.