Tamiflu: Shorten Flu Symptoms and Reduce Complications
| Product dosage: 75 mg | |||
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| 90 | $4.08
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Synonyms | |||
Tamiflu (oseltamivir phosphate) is a prescription antiviral medication indicated for the treatment of uncomplicated acute influenza in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. It is also approved for the prophylaxis (prevention) of influenza in patients 1 year and older. As a neuraminidase inhibitor, its primary mechanism of action involves inhibiting the replication and spread of the influenza A and B viruses within the respiratory tract. This targeted action is the cornerstone of its clinical utility, making it a critical tool in the management of seasonal and pandemic influenza outbreaks. Timely administration is paramount for achieving optimal therapeutic outcomes, as efficacy is greatest when treatment is initiated within the first two days of symptom onset.
Features
- Active Pharmaceutical Ingredient (API): Oseltamivir phosphate.
- Available Formulations: Capsules (30 mg, 45 mg, 75 mg) and a powder for oral suspension (6 mg/mL after reconstitution).
- Pharmacological Class: Neuraminidase inhibitor.
- Mechanism of Action: Inhibits the influenza viral neuraminidase enzyme, which is essential for the release of newly formed virus particles from infected cells and for the further spread of the infectious virus throughout the respiratory tract.
- Spectrum of Activity: Effective against both influenza A and B viruses.
- Prescription Status: Available by prescription only.
Benefits
- Reduces the duration of flu symptoms, such as fever, cough, sore throat, runny or stuffy nose, body aches, headache, and fatigue, by approximately one day compared to placebo.
- Lowers the risk of influenza-related complications, such as bronchitis, pneumonia, and hospitalization, particularly in high-risk populations.
- Can be used as a preventive measure to reduce the likelihood of catching the flu following exposure to a confirmed case (post-exposure prophylaxis).
- Available in multiple formulations (capsules and liquid suspension) to accommodate patients of different ages and those who have difficulty swallowing pills.
- A well-established antiviral with a extensive body of clinical evidence supporting its use in managing seasonal and pandemic influenza.
Common use
Tamiflu is primarily used for the treatment of acute, uncomplicated influenza in individuals who have presented with classic flu symptoms for no more than 48 hours. It is also commonly prescribed for the prophylaxis (prevention) of influenza in individuals aged 1 year and older. This is particularly relevant for post-exposure prophylaxis in household settings where one member is infected, or for seasonal prophylaxis in individuals at high risk of complications for whom the influenza vaccine is contraindicated, unavailable, or expected to have lower efficacy. Its use is guided by clinical diagnosis and, when available, positive rapid influenza diagnostic tests.
Dosage and direction
Dosage is based on the indication (treatment or prophylaxis), the patient’s age, and renal function. It is taken orally with or without food; however, administration with food may enhance tolerability and minimize potential gastrointestinal upset.
Treatment Dosage (for 5 days):
- Adults and Adolescents (13 years and older): 75 mg twice daily.
- Children (1 to 12 years): Dosage is weight-based.
- ≤15 kg: 30 mg twice daily
15 kg to 23 kg: 45 mg twice daily
23 kg to 40 kg: 60 mg twice daily
40 kg: 75 mg twice daily
- Infants (2 weeks to less than 1 year): 3 mg/kg twice daily.
Prophylaxis Dosage (for 10 days for post-exposure, or up to 6 weeks for community outbreak):
- Adults and Adolescents (13 years and older): 75 mg once daily.
- Children (1 to 12 years): Weight-based once-daily dosing.
- ≤15 kg: 30 mg once daily
15 kg to 23 kg: 45 mg once daily
23 kg to 40 kg: 60 mg once daily
40 kg: 75 mg once daily
Dosage adjustment is required for patients with creatinine clearance less than or equal to 60 mL/min. Please consult the full prescribing information for detailed dosing in renal impairment.
Precautions
- Tamiflu is not a substitute for early and annual influenza vaccination, which remains the primary method for preventing influenza.
- The efficacy of Tamiflu in patients who begin treatment after 48 hours of symptom onset has not been established.
- Use with caution in patients with any degree of renal impairment; dosage adjustment is mandatory.
- There is no evidence for efficacy of Tamiflu in any illness caused by agents other than influenza viruses A and B.
- Serious skin and hypersensitivity reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, have been reported. Discontinue use immediately if a skin reaction occurs.
- Patients with influenza may be at an increased risk for seizures, confusion, or abnormal behavior early in their illness; these neuropsychiatric events have been reported in patients taking Tamiflu, primarily in children. Closely monitor patients for signs of unusual behavior.
Contraindications
Tamiflu is contraindicated in patients with a known serious hypersensitivity to oseltamivir phosphate or any component of the product. Hypersensitivity reactions have included anaphylaxis and serious skin reactions.
Possible side effect
The most common adverse reactions are generally mild to moderate and transient, primarily occurring during the first two days of treatment.
- Very Common (≥1/10): Nausea, vomiting.
- Common (≥1/100 to <1/10): Abdominal pain, dyspepsia, diarrhea, headache.
- Uncommon (≥1/1,000 to <1/100): Dizziness, insomnia, fatigue, rash.
- Rare: Hepatitis, elevated liver enzymes, anaphylaxis and anaphylactoid reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, angioedema, seizure, confusion, abnormal behavior (including self-injury).
Drug interaction
Formal clinical drug interaction studies have shown no clinically significant interactions with amoxicillin, acetaminophen (paracetamol), antacids, or warfarin. Caution is advised when co-administering with drugs that compete for active renal secretion (e.g., probenecid, chlorpropamide, methotrexate), as this may lead to increased plasma concentrations of oseltamivir carboxylate (the active metabolite). Clinically significant interactions are not expected with the live attenuated influenza vaccine (LAIV); however, antiviral medications may inhibit viral replication and reduce the efficacy of LAIV.
Missed dose
If a dose is missed during the treatment regimen, the patient should take the missed dose as soon as possible. However, if it is near the time of the next scheduled dose (within 2 hours), the missed dose should be skipped, and the regular dosing schedule resumed. Patients should not double the dose to make up for a missed one.
Overdose
Single doses up to 1000 mg have been associated with nausea and/or vomiting. There is no specific antidote for oseltamivir overdose. General supportive care is recommended. The active metabolite is eliminated renally; therefore, monitoring and support of renal function may be considered in cases of significant overdose.
Storage
- Store capsules and powder for oral suspension at room temperature (25°C/77°F); excursions permitted between 15°C and 30°C (59°F to 86°F).
- Store the constituted (mixed) oral suspension under refrigeration (2°C-8°C/36°F-46°F) or at room temperature for up to 10 days. Do not freeze.
- Keep all medications out of the reach of children and pets.
Disclaimer
This information is for educational purposes only and does not constitute medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Never disregard professional medical advice or delay in seeking it because of something you have read here. The information provided is based on the product’s prescribing information but may not be exhaustive.
Reviews
“From a clinical perspective, Tamiflu remains a cornerstone of our antiviral arsenal for influenza. When initiated promptly in high-risk patients—the elderly, those with comorbidities like COPD or heart disease—we consistently observe a meaningful reduction in the progression to severe complications requiring hospitalization. Its value in outbreak settings, such as in long-term care facilities, for post-exposure prophylaxis is undeniable.” – Infectious Disease Specialist, 15 years experience.
“In my pediatric practice, having the liquid suspension available is crucial. While gastrointestinal side effects like vomiting can be a challenge, administering the dose with a small amount of food often mitigates this. The potential benefit of shortening a miserable illness for a child and reducing the risk of secondary otitis media or pneumonia often outweighs the transient discomfort of the medication.” – Pediatrician, 10 years experience.
“As a pharmacist, my role is to ensure appropriate dosing, especially renal adjustments for older adults, and to counsel patients on the 48-hour window for efficacy. Managing expectations is key; patients sometimes expect a ‘cure’ and are disappointed when symptoms persist, albeit for a shorter duration. Clear communication about its mechanism—shortening the illness, not eradicating it instantly—is vital for patient satisfaction.” – Clinical Pharmacist, 8 years experience.