Nat-Oseltamivir Capsule   

This product is manufactured by Natco Pharma Inc. using the ingredient oseltamivir.

This product is taken orally.


Why is it prescribed?

Oseltamivir is used for the treatment of uncomplicated acute illness due to influenza infection in adults and children over 1 year of age who have been symptomatic for no more than 2 days.  Oseltamavir when taken as recommended for the treatment of influenza, alleviates the symptoms and reduces their duration.

It is also used to prevent the onset of influenza in adults and children over 1 year of age who have been in contact with people who have influenza.



  • Use exactly as prescribed by your doctor.
  • Treatment should begin no more than 2 days after flu symptoms (e.g. sudden onset of fever, headache, tiredness, muscle weakness, runny or stuffy nose, sore throat and cough) have started to appear.
  • Prevention should begin within 2 days after coming into contact with someone with flu symptoms.
  • Take with food to reduce stomach upset.
  • You must complete the entire treatment. If you forget to take a dose, take it as soon as possible. Do not take double the amount if you miss one dose.
  • Keep in the original labeled container at room temperature (15 to 30 degrees centigrade) and keep in a dry place.


Other products that have the same ingredient as Nat-Oseltamivir Capsule are •Mint-oseltamivir capsule •Tamiflu® capsules •Tamiflu® suspension •

See other products used in the treatment of •flu •influenza •

Treatment of Influenza:

Adults and adolescents 13 years and older

  • 75 mg twice daily (in the morning and evening) for 5 days.

Children ages 1 to 12 years - Dosage is based on weight: 

  • ≤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  

Prevention of Influenza:

Adults and adolescents over 13 years of age:

  • 75mg once daily for 10 to 14 days

Children 1 to 12 years of age - Dosage is based on weight and duration is 10-14 days

  • ≤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 - 75mg once daily


Oseltamivir works by inhibiting an enzyme necessary for the flu virus to spread through the body.

Along with its needed effects, oseltamivir may cause some unwanted or undesirable effects. Generally, oseltamivir is well tolerated and many people will not experience unwanted effects. Possible unwanted effects include:

  • nausea
  • vomiting
  • diarrhea
  • stomach pain


  • dizziness
  • headache
  • trouble sleeping at night


  • cough
  • fatigue

Symptoms of skin reactions include flushing, rash, itching or swelling. Symptoms of hypersensitivity reactions include dizziness or breathing problems.
Cases of liver toxicity have also been reported, symptoms of which include yellowing of skin or eyes and dark urine.  Contact a physician if you experience these symptoms.



  • Oseltamivir is not a substitute for the flu shot. You should continue to get your flu shot as recommended by your doctor.
  • Before starting treatment with oseltamivir, make sure your doctor and pharmacist know if you ever had a bad reaction to oseltamivir, you have hereditary fructose intolerence, you are allergic to other medicine, food and dyes, you have kidney disease.
  • Drug Interactions: It is important to tell your doctor and pharmacist of any prescription or over-the-counter medications you are taking. To date, there does not appear to be any significant drug interactions with oseltamivir.
  • Use is not recommended in the following situation:
    • allergy to oseltamivir of any component of the preparation or to the related drug zanamivir.
  • Caution is recommended in the following situations:
    • kidney failure
    • liver disease
    • chronic illnesses such as heart and/or lung disease.

Use in pregnancy: Oseltamivir may be used during pregnancy.  Consult your doctor or pharmacist if you suspect you are pregnant.
Use while breastfeeding: Oseltamivir may be used if breastfeeding.  Consult your doctor or pharmacist before use.


Page Last Updated: 05/10/2016