Medically reviewed by Alan Lucks | MD, Alan Lucks MDPC Private Practice - New York on December 15th, 2025.
Oseltamivir is an antiviral medication primarily used to treat and prevent influenza.
Dosage varies based on age, condition (treatment or prevention), and weight, especially in children.
The typical adult treatment dose is 75 mg twice daily for 5 days; prevention doses differ.
Consult a healthcare provider for personalized dosing, especially for children or those with medical conditions.
Doctronic.ai offers fast, affordable telehealth visits to help answer dosage questions and connect you with licensed doctors.
Oseltamivir, also known as Tamiflu, is a medicine used to treat and help prevent influenza. It works by stopping the flu virus from spreading in your body. Oseltamivir works best when taken within the first 48 hours after flu symptoms start. Taking it early can help shorten the duration of your illness and make symptoms such as fever, cough, and body aches less severe.
Oseltamivir treats influenza A and B, but it does not work for other illnesses, such as the common cold or COVID-19. This is why it’s essential to know when this medicine is helpful and when it is not. Doctors often prescribe oseltamivir for people who are very sick, older adults, young children, or those with health problems that make the flu more dangerous.
The dose of oseltamivir depends on your age, weight, and whether you are using it to treat the flu or to prevent it after exposure. Taking the correct dose at the right time helps the medicine work better and lowers the chance of side effects.
If you’re unsure about your dose or have questions about taking oseltamivir, telehealth services like Doctronic.ai can help. These services let you talk to a doctor quickly, which is especially helpful during busy flu seasons.
Form |
Strength |
Typical Adult Dose |
Typical Children’s Dose |
Frequency |
Route |
Maximum Daily Dose |
|---|---|---|---|---|---|---|
Capsule |
30 mg, 45 mg, 75 mg |
75 mg twice daily |
Weight-based (see below) |
Twice daily |
Oral |
150 mg/day |
Oral Suspension |
12 mg/mL |
75 mg twice daily |
Weight-based (see below) |
Twice daily |
Oral |
150 mg/day |
For adults and adolescents aged 13 years and older, the recommended dose is 75 mg twice daily for 5 days. Treatment should begin within 48 hours of symptom onset for best results.
Children under 13 years receive doses based on weight:
15 kg or less: 30 mg twice daily
15 to 23 kg: 45 mg twice daily
23 to 40 kg: 60 mg twice daily
Over 40 kg: 75 mg twice daily
The duration is also 5 days for children.
For adults and adolescents, the standard dose for prevention is 75 mg once daily for at least 10 days following close contact with an infected person. For community outbreaks, the duration may extend up to 6 weeks.
Children’s prevention doses are similarly weight-based but given once daily:
15 kg or less: 30 mg once daily
15 to 23 kg: 45 mg once daily
23 to 40 kg: 60 mg once daily
Over 40 kg: 75 mg once daily
Adults typically take 75 mg twice daily for treatment and 75 mg once daily for prevention. The treatment course usually lasts 5 days, while prevention can range from 10 days to several weeks, depending on exposure risk.
It’s important to start treatment early, ideally within 48 hours of developing flu symptoms, to maximize effectiveness.
Children’s doses are carefully calculated based on weight to ensure safety and effectiveness. The oral suspension form is often preferred for younger children who cannot swallow capsules.
Both treatment and prevention doses vary, but follow the weight-based guidelines outlined above. Always measure doses precisely and consult a healthcare professional if uncertain.
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed one and continue with your regular schedule. Do not double the dose to catch up, as this can increase side effects.
Patients with reduced kidney function may require dose adjustments. For example, those with severe renal impairment might need a reduced dose of 30 mg once daily instead of the standard 75 mg. This helps prevent drug accumulation and potential toxicity.
Currently, no specific dose adjustments are recommended for liver impairment or other common conditions, but always inform your healthcare provider about your full medical history before starting oseltamivir.
Taking more than the recommended dose can lead to nausea, vomiting, confusion, or other side effects. If an overdose is suspected, seek emergency medical attention immediately.
Common side effects include nausea and vomiting, which often improve if the medication is taken with food.
Start treatment as soon as flu symptoms appear for the best results.
Take doses with food to reduce stomach upset.
Complete the full course even if you start feeling better early.
Store the medication as directed, especially the oral suspension.
Consult a healthcare provider if you experience severe side effects or allergic reactions.
Understanding the right oseltamivir dose can be confusing, especially when factoring in age, weight, and medical conditions. Doctronic.ai offers a unique AI-powered telehealth service that provides personalized medical advice quickly and affordably. You can get answers to your dosage questions or schedule a video visit with licensed doctors anytime, anywhere in the U.S.
This service is especially helpful if you need a second opinion or want to confirm your dosage before starting treatment. With over 10 million users and growing, Doctronic is changing how people access primary care.
Oseltamivir is a powerful tool in managing influenza, but its effectiveness depends on taking the right dose at the right time. Follow dosing guidelines carefully, and don’t hesitate to seek professional advice if you have questions. Personalized care through telehealth platforms like Doctronic.ai can make this process easier and safer.
Oseltamivir is generally considered safe during pregnancy, but you should always consult your healthcare provider before starting treatment.
Oseltamivir can be used in children as young as 2 weeks old, but dosing must be carefully managed by a healthcare professional.
Mild side effects, such as nausea, usually pass quickly. If you experience severe symptoms or allergic reactions, seek medical help immediately.
Yes, oseltamivir can be used for prevention in high-risk situations even if vaccinated, but discuss this with your doctor.
Ideally, start within 48 hours of exposure to an infected person for maximum effectiveness.
Key TakeawaysOseltamivir is an antiviral medication primarily used to treat and prevent influenza.Dosage varies based on age, condition (treatment or prevention), and weight, [...]
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