cimetidine vs oseltamivir
PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.
Side-by-side comparison of cimetidine and oseltamivir. 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
7.2 Drugs Without Clinically Significant Drug Interaction with Oseltamivir Phosphate for Oral Suspension No dose adjustments are needed for either oseltamivir or the concomitant drug when coadministering oseltamivir with amoxicillin, acetaminophen, aspirin, cimetidine, antacids (magnesium and aluminum hydroxides and calcium carbonates), rimantadine, amantadine, or warfarin [see Clinical Pharmacology (12.3) ] .
Tagamet
Tamiflu
Cimetidine (Tagamet) reduces stomach acid. It is used to treat ulcers, heartburn, and other conditions where too much acid is produced.
Oseltamivir (Tamiflu) is an antiviral medicine. It helps treat and prevent the flu (influenza A and B).
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 the flu in people 2 weeks and older who have had symptoms for no more than 48 hours. It can also prevent the flu in people 1 year and older. Remember that this medicine is not a substitute for your yearly flu shot. It's important to get vaccinated every year.
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.
Oseltamivir stops the flu virus from spreading in your body. It does this by blocking a protein on the virus called neuraminidase. This helps you get better faster or prevents you from getting sick.
- • Headache
- • Dizziness
- • Diarrhea
- • Nausea
- • Vomiting
- • Headache
- • Pain
- Chronic Kidney Disease 1,264
- Acute Kidney Injury 710
- Renal Failure 694
- Nausea 681
- Fatigue 598
- Vomiting 444
- Nausea 443
- Headache 381
- Pneumonia 368
- Condition Aggravated 332
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.
Rarely, this medicine has been linked to serious skin reactions and allergic reactions. Stop taking this medicine and get medical help right away if you have signs of an allergic reaction or a severe skin rash. Some people, especially children, may experience confusion or unusual behavior while taking this medicine. Watch for any changes in behavior and tell your doctor right away.
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.
Tell your doctor if you are pregnant or plan to become pregnant. Studies suggest this medicine does not increase the risk of birth defects. Talk to your doctor about the risks and benefits of taking this medicine while pregnant or breastfeeding.
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How to Read This cimetidine vs oseltamivir Comparison
cimetidine is classified in the H2 Receptor Antagonist drug class, while oseltamivir sits within the Neuraminidase Inhibitor (Antiviral) 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 3,947 submissions while oseltamivir has 1,968. 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 these drugs do not interfere with each other's absorption or removal from the body.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for cimetidine or oseltamivir.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.