Oseltamivir

Oseltamivir is a prescription medication used as a prophylaxis and treatment of Influenza A and B.

• Oseltamivir is available under the following different brand names: Tamiflu

Adult and pediatric dosage

Capsule

• 30mg
• 45mg
• 75mg

Powder for oral suspension

• 6mg/mL

Influenza A and B Prophylaxis

Adult dosage

• 75 mg orally once daily for at least 10 days
• Initiate within 48 hours of exposure
• For community outbreak, may administer for up to 6 weeks

Pediatric dosage

• Children younger than 1 year of age: Safety and efficacy not established for prophylaxis
• Children 1-12 years of age:
  • Weighing less than 15 kg: 30 mg orally once daily for 10 days
  • Weight between 15-23 kg: 45 mg orally once daily for 10 days
  • Weight between 23-40 kg: 60 mg orally once daily for 10 days
  • Weighing over 40 kg: 75 mg orally once daily for 10 days
• Children 13 years of age or older: 
  • 75 mg orally once daily for at least 10 days

Influenza A and B Treatment

Adult dosage

• 75 mg orally every 12 hours for 5 days
• Initiate within 48 hours of influenza symptom onset

Pediatric dosage

• Children younger than 2 weeks of age: Safety and efficacy not established for treatment
• Children 2 weeks to younger than 1 year of age:
  • 3 mg/kg orally every 12 hours for 5 days
  • Children 1-12 years of age: 
  • Weighing less than 15 kg: 30 mg orally every 12 hours for 5 days
  • Weight between 15-23 kg: 45 mg orally every 12 hours for 5 days
  • Weight between 23-40 kg: 60 mg orally every 12 hours for 5 days
  • Weighing over 40 kg: 75 mg orally every 12 hours for 5 days
• Children 13 year of age or older:
  • 75 mg orally every 12 hours for 5 days

Dosage Considerations – Should be Given as Follows: 

• See "Dosages."

Common side effects of Oseltamivir include:

• nausea, 
• vomiting, 
• headache, and 
• pain

Serious side effects of Oseltamivir include:

• hives, 
• difficulty breathing, 
• swelling of the face, lips, tongue, or throat, 
• fever, 
• sore throat, 
• burning eyes, 
• skin pain, 
• red or purple skin rash with blistering and peeling, 
• sudden unusual mood changes or behavior, 
• sudden confusion, 
• tremors, 
• shaking, 
• unusual behavior, and
• hallucinations

Rare side effects of Oseltamivir include:

• none 

This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them.  Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

Oseltamivir has severe interactions with no other drugs.

Oseltamivir has serious interactions with the following drugs:

• pretomanid

Oseltamivir has moderate interactions with the following drugs:

• clopidogrel
• influenza virus vaccine quadrivalent
• influenza virus vaccine quadrivalent, adjuvanted
• influenza virus vaccine quadrivalent, cell-cultured
• influenza virus vaccine quadrivalent, intranasal
• influenza virus vaccine quadrivalent, recombinant
• influenza virus vaccine trivalent
• influenza virus vaccine trivalent, adjuvanted
• influenza virus vaccine trivalent, recombinant 
• probenecid 

Oseltamivir has minor interactions with no other drugs. 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drugs interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use.  Keep a list of all your medications with you, and share this information with your doctor and pharmacist.  Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

Contraindications

• Hypersensitivity 

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Oseltamivir?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Oseltamivir?”

Cautions

• Use caution in patients with chronic cardiac disease, severe hepatic impairment, renal impairment, respiratory disease
• Delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, reported in patients with influenza who were receiving therapy; relationship to therapy not established
• Most effective when used within 24-48 hours of onset of symptoms
• Safety and efficacy for prophylaxis of influenza not established for children younger than 1year of age
• Oral suspension should be mixed prior to dispensing
• Safety and efficacy in immunocompromised patients not established
• Therapy is not a substitute for influenza virus vaccine
• Serious skin/hypersensitivity reactions such as Stevens-Johnson Syndrome, toxic epidermal necrolysis and erythema multiforme; discontinue therapy and initiate appropriate treatment if allergic-like reactions occur or are suspected
• Prescribers should be alert to potential for secondary bacterial infections and treat them as appropriate
• Neuropsychiatric events
  • Delirium and abnormal behavior leading to injury, including fatalities, reported postmarketing in patients with influenza receiving oseltamivir
  • Because these events were reported voluntarily during clinical practice, frequency cannot be estimated, but occurrence is uncommon
  • Reported primarily among pediatric patients and often had an abrupt onset and rapid resolution
  • Unable to establish causality between these events and oseltamivir
  • These events may occur in the setting of encephalitis or encephalopathy, but can occur without obvious severe disease; closely monitor oseltamivir-treated patients with influenza for signs of abnormal behavior
• Oral suspension and hereditary fructose intolerance
  • Fructose can be harmful to patients with hereditary fructose intolerance
  • One dose of 75 mg oral suspension delivers 2 g of sorbitol; this is above the daily maximum limit of sorbitol for patients with hereditary fructose intolerance, and may cause dyspepsia and diarrhea

Pregnancy and Lactation

• There are no adequate and well–controlled studies in pregnant women to inform a drug–associated risk of adverse developmental outcomes; available published epidemiological data suggest that the drug, 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
• Pregnant women are at higher risk of severe complications from influenza, which may lead to adverse pregnancy and/or fetal outcomes including maternal death, stillbirths, birth defects, preterm delivery, low birth weight and small for gestational age
• Based on limited published data, have shown the drug to be present in human milk at low levels considered unlikely to lead to toxicity in the breastfed infant; postmarketing experience has not reported any information to suggest serious adverse effects to drug exposure via breast milk in infants; it is not known if drug affects human milk production; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from drug or from underlying maternal condition.