oseltamivir
Brand names: Tamiflu
Oseltamivir (Tamiflu) is an antiviral medicine. It helps treat and prevent the flu (influenza A and B).
Drug Shortage Alert
oseltamivir is currently listed as to be discontinued by the FDA. Affected manufacturer: Genentech, Inc.
View all drug shortages →Drug Pricing (NADAC)
Brand Price
$14.62/unit
Generic Price
$0.18/unit
Generic Savings
99%
Generic Available
Yes (30 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats the flu in people 2 weeks and older who have had symptoms for no more than 48 hours.
Common side effects
Nausea, Vomiting, Headache
Key warnings
Rarely, this medicine has been linked to serious skin reactions and allergic reactions.
How It Works
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.
How to Take It
Take this medicine as directed by your doctor. You can take it with or without food. Taking it with food may help reduce stomach upset. Make sure to use the oral suspension form if you cannot swallow capsules.
Pregnancy & 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.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store the dry powder at room temperature. After mixing with water, store in the refrigerator for up to 17 days, or at room temperature for up to 10 days. Keep the bottle in the carton to protect from light.
Side Effects (from patient reports)
Based on 5,697 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 7,575 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
7,575
Death-Related Reports
1,149
Hospitalization Reports
2,529
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | OFF LABEL USE | 1,776 |
| 2 | DRUG INEFFECTIVE | 713 |
| 3 | NO ADVERSE EVENT | 582 |
| 4 | VOMITING | 444 |
| 5 | NAUSEA | 443 |
| 6 | HEADACHE | 381 |
| 7 | PNEUMONIA | 368 |
| 8 | CONDITION AGGRAVATED | 332 |
| 9 | INFLUENZA | 330 |
| 10 | PRODUCT USE IN UNAPPROVED INDICATION | 328 |
| 11 | DRUG INTOLERANCE | 325 |
| 12 | DYSPNOEA | 283 |
| 13 | ABDOMINAL PAIN | 280 |
| 14 | SEPSIS | 260 |
| 15 | DIARRHOEA | 259 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
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.
Known Drug Interactions
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) ] .
Mechanism: These two drugs do not have a meaningful impact on how the body processes or uses either medication.
What to do: You can take these medicines together without any changes to your dose.
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) ] .
Mechanism: There is no significant interaction between these drugs that would change how they work in your body.
What to do: No dose adjustments are needed when taking these two medications at the same time.
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) ] .
Mechanism: These medications do not interfere with each other's levels or effectiveness in the body.
What to do: It is safe to take these medicines together at your usual prescribed doses.
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) ] .
Mechanism: These drugs do not change how the body handles or clears either medicine from your system.
What to do: You can continue taking your normal doses of both medications as prescribed.
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) ] .
Mechanism: These drugs do not interfere with each other's absorption or removal from the body.
What to do: No dose adjustments are necessary when using these medications together.
Common Questions
Can I get a flu shot while taking this medicine?
What should I do if I have kidney problems?
Can I take this medicine with other medicines?
What if I am allergic to one of the ingredients?
How long should I take this medicine?
What if my symptoms get worse?
Can this medicine prevent bacterial infections?
Is this medicine safe for children?
What does 'prophylaxis' mean?
Can I use the constituted suspension after 20 days if refrigerated?
What are the common side effects of oseltamivir?
Does oseltamivir interact with other medications?
What drug class is oseltamivir?
Is there a generic version of oseltamivir?
Is oseltamivir safe during pregnancy?
Is oseltamivir currently in shortage?
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What the FDA Data Shows for oseltamivir
The FDA label for oseltamivir (sold under brand names such as Tamiflu) classifies it as a prescription-only medication in the Neuraminidase Inhibitor (Antiviral) class. This medicine treats the flu in people 2 weeks and older who have had symptoms for no more than 48 hours. Official labeling lists 4 commonly reported side effects, including Nausea, Vomiting, Headache.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 5,697 voluntary reports. The database also lists 5 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.18 versus $14.62 for the brand — a 99% generic savings.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC). Shortage status: FDA Drug Shortages Database.
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: May 15, 2024
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages