Oseltamivir

Oseltamivir is an antiviral drug with activity against influenza virus [see Microbiology (12.4) ].

• Oseltamivir phosphate for oral suspension is an influenza neuraminidase inhibitor (NAI) indicated for: Treatment of acute, uncomplicated influenza A and B in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. ( 1.1 ) Prophylaxis of influenza A and B in patients 1 year and older.ICD-10: J11.1

• Oseltamivir phosphate for oral suspension is contraindicated in patients with known serious hypersensitivity to oseltamivir or any component of the product. Severe allergic reactions have included anaphylaxis and serious skin reactions including toxic epidermal necrolysis, Stevens-Johnson Syndrome, and erythema multiforme [see Warnings and Precautions (5.1) ] .contraindicated

Treatment of influenza Adults and adolescents (13 years and older): 75 mg twice daily for 5 days ( 2.2 ) Pediatric patients 1 to 12 years of age: Based on weight twice daily for 5 days ( 2.2 ) Pediatric patients 2 weeks to less than 1 year of age: 3mg/kg twice daily for 5 days ( 2.2 ) Renally impaired adult patients (creatinine clearance >30 to 60 mL/min): Reduce to 30 mg twice daily for 5 days ( 2.4 ) Renally impaired adult patients (creatinine clearance >10 to 30 mL/min): Reduce to 30 mg once daily for 5 days ( 2.4 ) ESRD patients on hemodialysis: Reduce to 30 mg immediately and then 30 mg after every hemodialysis cycle. Treatment duration not to exceed 5 days ( 2.4 ) ESRD patients on CAPD: Reduce to a single 30 mg dose immediately ( 2.4 ) Prophylaxis of influenza Adults and adolescents (13 years and older): 75 mg once daily for at least 10 days ( 2.3 ) Community outbreak: 75 mg once daily for up to 6 weeks ( 2.3 ) Pediatric patients 1 to 12 years of age: Based on weight once daily for 10 days ( 2.3 ) Community outbreak: Based on weight once daily for up to 6 weeks ( 2.3 ) Renally impaired adult patients (creatinine clearance >30 to 60 mL/min): Reduce to 30 mg once daily ( 2.4 ) Renally impaired adult patients (creatinine clearance >10 to 30 mL/min): Reduce to 30 mg once every other day ( 2.4 ) ESRD patients on hemodialysis: Reduce to 30 mg immediately and then 30 mg after alternate hemodialysis cycles for the recommended duration of prophylaxis ( 2.4 ) ESRD patients on CAPD: Reduce to 30 mg immediately and then 30 mg once weekly for the recommended duration of prophylaxi…

Serious skin/hypersensitivity reactions such as Stevens-Johnson Syndrome, toxic epidermal necrolysis and erythema multiforme: Discontinue oseltamivir phosphate for oral suspension and initiate appropriate treatment if allergic-like reactions occur or are suspected. ( 5.1 ) Neuropsychiatric events: Patients with influenza, including those receiving oseltamivir phosphate for oral suspension, particularly pediatric patients, may be at an increased risk of confusion or abnormal behavior early in their illness. Monitor for signs of abnormal behavior. ( 5.2 ) 5.1 Serious Skin/Hypersensitivity Reactions Cases of anaphylaxis and serious skin reactions including toxic epidermal necrolysis, Stevens-Johnson Syndrome, and erythema multiforme have been reported in postmarketing experience with oseltamivir phosphate for oral suspension. Stop oseltamivir phosphate for oral suspension and institute appropriate treatment if an allergic-like reaction occurs or is suspected. The use of oseltamivir phosphate for oral suspension is contraindicated in patients with known serious hypersensitivity to oseltamivir phosphate for oral suspension [see Contraindications (4) and Adverse Reactions (6.2) ] . 5.2 Neuropsychiatric Events There have been postmarketing reports of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving oseltamivir phosphate for oral suspension [see Adverse Reactions (6.2) ] .

The following serious adverse reactions are discussed below and elsewhere in the labeling: Serious skin and hypersensitivity reactions [see Warnings and Precautions (5.1) ] Neuropsychiatric events [see Warnings and Precautions (5.2) ] Most common adverse reactions (> 1% and more common than with placebo): Treatment studies – Nausea, vomiting, headache. ( 6.1 ) Prophylaxis studies – Nausea, vomiting, headache, pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Lannett Company, Inc. at 1-844-834-0530 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse Reactions from Treatment and Prophylaxis Trials in Adult and Adolescent Subjects (13 years of age and older) The overall safety profile of oseltamivir phosphate for oral suspension is based on data from 2,646 adult and adolescent subjects that received the recommended dosage of 75 mg orally twice daily for 5 days for treatment of influenza and 1,943 adult and adolescent subjects that received the recommended dosage of 75 mg orally once daily for up to 6 weeks for prophylaxis of influenza in clinical trials. The most common adverse reactions in the pooled treatment and pooled prophylaxis trials in adults and adolescents are displayed in Table 5 .

8.1 Pregnancy Risk Summary There are no adequate and well-controlled studies with oseltamivir phosphate for oral suspension in pregnant women to inform a drug-associated risk of adverse developmental outcomes. Available published epidemiological data suggest that oseltamivir phosphate for oral suspension, taken in any trimester, is not associated with an increased risk of birth defects. However, these studies individually are limited by small sample sizes, use of different comparison groups, and some lacked information on dose, which preclude a definitive assessment of the risk [see Data and Clinical Pharmacology (12.3) ] . In animal reproduction studies with oseltamivir, no adverse developmental effects were observed at clinically relevant exposures (see Data ) . The background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage is 2 to 4% and 15 to 20%, respectively.

Metabolism

Absorption and Bioavailability Oseltamivir is absorbed from the gastrointestinal tract after oral administration of oseltamivir phosphate and is extensively converted predominantly by hepatic esterases to oseltamivir carboxylate. At least 75% of an oral dose reaches the systemic circulation as oseltamivir carboxylate and less than 5% of the oral dose reaches the systemic circulation as oseltamivir (see Table 6 ).

Reports of overdoses with oseltamivir phosphate have been received from clinical trials and during postmarketing experience. In the majority of cases reporting overdose, no adverse reactions were reported. Adverse reactions reported following overdose were similar in nature to those observed with therapeutic doses of oseltamivir phosphate for oral suspension [see Adverse Reactions (6) ] .

• Oct 27, 1999NDANDA021087Roche
• Dec 14, 2000NDANDA021246Roche
• Aug 3, 2016ANDAANDA202595Natco
• Feb 24, 2017ANDAANDA208578Zydus Pharms
• May 17, 2017ANDAANDA209093Amneal Pharms
• Sep 14, 2017ANDAANDA207211Macleods Pharms Ltd
• Sep 14, 2017ANDAANDA209113Zydus Pharms
• Oct 31, 2017ANDAANDA208823Alvogen

1. 1Off Label Use2,0928.7%
2. 2Vomiting2,0448.5%
3. 3No Adverse Event1,5856.6%
4. 4Nausea1,5406.4%
5. 5Drug Ineffective1,2615.2%
6. 6Influenza1,1724.9%
7. 7Diarrhoea1,0334.3%
8. 8Dyspnoea9874.1%
9. 9Abnormal Behaviour9634.0%
10. 10Headache9293.9%
11. 11Pyrexia9223.8%
12. 12Pneumonia9043.8%
13. 13Hallucination8743.6%
14. 14Rash7263.0%
15. 15Cough6562.7%

Recent PubMed references pinned to Oseltamivir as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Fe(2)O(3)-based nanozyme synergistic with oseltamivir for broad-spectrum inhibition of influenza A virus.
  International immunopharmacology · 2026 · Li Y, Jiang Y, Zhang Y, et al.
  PMID 42066550DOI 10.1016/j.intimp.2026.116753
• Prompt and Intensive Antiviral Chemoprophylaxis in Nursing Home Influenza Outbreaks.
  JAMA internal medicine · 2026 · Silva JBB, Hsieh HT, Howe CJ, et al.
  PMID 41910957DOI 10.1001/jamainternmed.2026.0401
• Use of baloxavir as adjunctive antiviral therapy to neuraminidase inhibitors in severely immunocompromised individuals infected with influenza.
  Antimicrobial agents and chemotherapy · 2026 · Vetter P, Cabecinhas ARG, Schibler M, et al.
  PMID 41891860DOI 10.1128/aac.01659-25
• Oseltamivir aziridines are potent influenza neuraminidase inhibitors and imaging agents.
  Proceedings of the National Academy of Sciences of the United States of America · 2026 · Vriends MBL, Moran E, Calvelo M, et al.
  PMID 41871250DOI 10.1073/pnas.2504045123
• Afebrile Presentation in COPD Patients with Influenza A: A Risk Factor for Prolonged Viral Shedding.
  International journal of chronic obstructive pulmonary disease · 2026 · Fan Y, Fan J, Ma L, et al.
  PMID 41853748DOI 10.2147/COPD.S559844
• Therapeutic mechanisms of early oseltamivir administration in the management of mild COVID-19 through the sympathetic nervous system: A scoping review.
  Journal of virological methods · 2026 · Chiba S
  PMID 41850438DOI 10.1016/j.jviromet.2026.115386
• Evaluating the Health Economic Impacts of Baloxavir Marboxil and Oseltamivir for the Treatment of Influenza in Adult Outpatients in Hong Kong: A Cost-Effectiveness Analysis.
  Influenza and other respiratory viruses · 2026 · Chen R, Shao Z, Bi K, et al.
  PMID 41784471DOI 10.1111/irv.70243
• Baloxavir outperforms oseltamivir, favipiravir, and amantadine in treating lethal influenza A(H5N1) HA clade 2.3.4.4b infection in mice.
  Nature communications · 2026 · Andreev K, Jones JC, Kandeil A, et al.
  PMID 41714318DOI 10.1038/s41467-026-69721-5

The 10 most recently updated of 173 ClinicalTrials.gov registrations naming Oseltamivir as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• COmbination Therapy With Baloxavir and Oseltamivir 1 for Hospitalized Patients With Influenza (The COMBO Trial 1)
  Completed · Phase 2 · Phase 3 · Interventional · 15 enrolled · Bassett Healthcare
  NCT04327791updated 2026-05-14
• Post-exposure Influenza Prophylaxis in a Hospital Setting
  Active not recruiting · Phase 3 · Interventional · 200 enrolled · University Medical Centre Ljubljana
  NCT07496736updated 2026-04-30
• Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Chinese Pediatric Participants 1 to <12 Years of Age With Influenza Symptoms
  Completed · Phase 3 · Interventional · 100 enrolled · Hoffmann-La Roche
  NCT06774859updated 2026-04-27
• Randomised Evaluation of COVID-19 Therapy
  Recruiting · Phase 3 · Interventional · 70,000 enrolled · University of Oxford
  NCT04381936updated 2026-04-21
• Study to Assess the Safety and Efficacy of ZX-7101A for Oral Suspension in Chinese Pediatric Participants 2 to 11 Years of Age With Influenza
  Completed · Phase 3 · Interventional · 169 enrolled · Nanjing Zenshine Pharmaceuticals
  NCT07095257updated 2026-04-16
• A Phase 2 Trial Comparing Antiviral Treatments in Early Symptomatic Influenza
  Recruiting · Phase 2 · Interventional · 3,000 enrolled · University of Oxford
  NCT05648448updated 2026-04-14
• Dexmedetomidine-Enhanced PCIA After Lobectomy in Nicotine-Dependent Patients
  Withdrawn · Phase 4 · Interventional · 0 enrolled · Shenyang Sixth People's Hospital
  NCT07306702updated 2026-04-13
• Pharmacokinetics, Pharmacodynamics, and Safety Profile of Understudied Drugs Administered to Children Per Standard of Care (POPS)
  Recruiting · Observational · 5,000 enrolled · Duke University
  NCT04278404updated 2026-04-06
• Suraxavir Marboxil And Oseltamivir for Influenza Prophylaxis Under a Hospital-based Setting
  Recruiting · Phase 3 · Interventional · 384 enrolled · Capital Medical University
  NCT07236814updated 2026-03-23
• Effectiveness of Xuanfei Jiangzhuo Decoction for Influenza-Induced AECOPD
  Not yet recruiting · Observational · 300 enrolled · Tianjin Medical University
  NCT07393685updated 2026-03-12

Frequently asked questions

How does Oseltamivir work?

Oseltamivir is an antiviral drug with activity against influenza virus [see Microbiology (12.4) ].

What is Oseltamivir used for?

According to FDA labeling, Oseltamivir carries indications including: Oseltamivir phosphate for oral suspension is an influenza neuraminidase inhibitor (NAI) indicated for: Treatment of acute, uncomplicated influenza A and B in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. ( 1.1 ) Prophylaxis of influenza A and B in patients 1 year and older.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Oseltamivir?

Oseltamivir is classified as Neuraminidase inhibitors, Neuraminidase Inhibitor, Neuraminidase Inhibitors, Unknown Physiological Effect.

What are the brand names for Oseltamivir?

Oseltamivir is marketed under brand names including Tamiflu.

What are the contraindications for Oseltamivir?

Oseltamivir labeling lists contraindications including: Oseltamivir phosphate for oral suspension is contraindicated in patients with known serious hypersensitivity to oseltamivir or any component of the product. Severe allergic reactions have included anaphylaxis and serious skin reactions including toxic epidermal necrolysis, Stevens-Johnson Syndrome, and erythema multiforme [see Warnings and Precautions (5.1) ] .. Always consult the full prescribing information and a clinician.