cimetidine vs metronidazole
Side-by-side comparison of cimetidine and metronidazole. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
minor Known Drug Interaction
Drugs that Inhibit CYP450 Enzymes The simultaneous administration of drugs that decrease microsomal liver enzyme activity, such as cimetidine, may prolong the half-life and decrease plasma clearance of metronidazole.
Recommendation: Your doctor may need to monitor you more closely for side effects since the drug will leave your system more slowly.
Tagamet
Flagyl
Cimetidine (Tagamet) reduces stomach acid. It is used to treat ulcers, heartburn, and other conditions where too much acid is produced.
Metronidazole is an antibiotic medicine. It fights bacteria and certain parasites in your body.
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.
Metronidazole treats infections like trichomoniasis, amebiasis, and certain anaerobic bacterial infections. Trichomoniasis is a sexually transmitted infection. Amebiasis includes infections of the intestines and liver. Anaerobic bacteria cause infections inside the abdomen, on the skin, and in the female reproductive system.
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.
Metronidazole works by entering the bacteria or parasite and damaging its DNA. This damage stops the bacteria or parasite from growing and multiplying. Eventually, the infection is cleared.
- • Headache
- • Dizziness
- • Diarrhea
- • Nausea
- • Headache
- • Loss of appetite
- • Vomiting
- • Diarrhea
- Long-term kidney disease 1,264
- Sudden kidney damage 710
- Kidney failure 694
- Feeling sick to your stomach 681
- Feeling tired 599
- Nausea 4,691
- Diarrhoea 4,116
- Vomiting 3,283
- Pyrexia 3,224
- Drug Hypersensitivity 3,138
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.
Metronidazole can cause cancer in mice and rats. Only use it for the conditions listed in this leaflet. Do not drink alcohol or use products with propylene glycol while taking this medicine, and for 3 days after.
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.
Do not take metronidazole during the first three months of pregnancy. Talk to your doctor if you are pregnant or breastfeeding before taking this medicine.
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How to Read This cimetidine vs metronidazole Comparison
cimetidine is classified in the H2 Receptor Antagonist drug class, while metronidazole sits within the Nitroimidazole Antibiotic class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are split between OTC and prescription status, which affects access and supervision.
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 metronidazole has 18,452. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to cimetidine slows down how fast your liver breaks down metronidazole, which causes the medicine to stay in your body longer.. 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 metronidazole - 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.