Tamiflu

The most frequent side effects of oseltamivir are:

• Nausea
• Vomiting
• Diarrhea
• Bronchitis
• Abdominal pain
• Headache
• Dizziness

Administering oseltamivir after meals helps reduce nausea.

Other reported adverse events include:

• Allergic reactions
• Skin reactions
• Seizures
• Behavioral disturbances
• Aggravation of diabetes

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Tamiflu is available in 30 milligram (mg) and 75 mg tablets and a 6 mg/milliliter (ml) syrup.

The usual dose is 75 mg of Tamiflu twice a day for 5 days for adults who have symptoms of influenzas A or B.  

If you don't yet have symptoms, your doctor may prescribe one, 75 mg tablet of Tamiflu a day for 10 days. 

Doctors base the dose for children under age 13 on their age and weight. 

Tamiflu Overdose

If you suspect an overdose, contact a poison control center or emergency room immediately.

You can contact a poison control center at (800) 222-1222.

Missed Dose of Tamiflu

If you miss a dose of Tamiflu, try to take it as soon as you remember.

If it's almost time for your next dose, skip the missed dose and take your next dose at its usual time.

Do not take two doses of the medication at the same time.

Tamiflu is a prescription medication used to prevent and treat "the flu", an infection caused by the influenza virus. Tamiflu belongs to a group of drugs called neuraminidase inhibitors, which attack the influenza virus to stop it from spreading inside your body.

This medication comes in capsule and suspension (liquid) forms and is usually taken once or twice a day, with or without food.

Common side effects include nausea and vomiting.

The most common side effects of Tamiflu are mild to moderate nausea and vomiting,usually during the first 2 days of treatment. Taking Tamiflu with food may reduce the chance of getting these side effects.

If you develop an allergic reaction or severe rash, stop taking Tamiflu and contact your healthcare professional.

People with the flu, particularly children and adolescents, may be at an increased risk of:

• seizures
• confusion
• abnormal behavior early during their illness

These events may occur shortly after beginning Tamiflu or may occur when flu is not treated. These events are uncommon but may result in accidental injury to the patient. Therefore, patients should be observed for signs of unusual behavior and a healthcare professional should be contacted immediately if the patient shows any signs of unusual behavior.

Do not take Tamiflu if you are allergic to any ingredients in it.

Before starting treatment, make sure your healthcare professional knows if you:

• take any other medicines
• are pregnant or planning to become pregnant
• are breastfeeding

Tamiflu is normally not recommended for use during pregnancy or nursing, as the effects on the unborn child or nursing infant are unknown. Tamiflu is not recommended for use in children younger than 2 weeks of age.

Tell your healthcare professional if you have any type of kidney disease, heart disease, respiratory disease, or any serious health condition.

Tamiflu for oral suspension may contain sorbitol. Sorbitol may cause upset stomach and diarrhea in patients with a family history of fructose intolerance.

Tell your healthcare provider if you are allergic to any ingredient in Tamiflu.

Before starting treatment, make sure your healthcare professional knows if you:

• have kidney disease
• have heart disease
• have lung disease
• have any other serious health condition 
• are pregnant, planning to become pregnant, or breastfeeding. Tamiflu is normally not recommended for use during pregnancy or nursing, as the effects on the unborn child or nursing infant are unknown. Tamiflu is not recommended for use in children younger than 2 weeks of age.

Tell your healthcare provider about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you have received nasally administered influenza virus vaccine during the past two weeks.

Take Tamiflu exactly as prescribed by your doctor. Follow the directions on your prescription label carefully. 

If you have the flu:

Take Tamiflu twice a day for 5 days, once in the morning and once in the evening. You should complete the entire treatment of 10 doses (capsules or suspension), even if you feel better.

To prevent the flu:

If someone in your home has the flu, take Tamiflu once a day for 10 days or for as long as prescribed. You can take Tamiflu for up to 6 weeks if you are exposed to the flu because of an outbreak in your community. Follow your healthcare professional's advice on how long to take Tamiflu.

Although there is a fixed dosing regimen for patients 1 year and older according to weight categories, the dosing for children younger than 1 year must be calculated for each patient based on their exact weight. These children should receive 3 milligrams per kilogram twice daily for five days. These smaller doses will require a different dispenser.

Oseltamivir is an antiviral medication that blocks the actions of influenza virus types A and B in your body.

Oseltamivir is used to treat influenza in people 2 weeks of age and older who have had flu symptoms for 2 days or less. Oseltamivir may also be given to prevent influenza in people who are at least 1 year old, who may be exposed but do not yet have symptoms. Oseltamivir will not treat the common cold.

It is dangerous to purchase oseltamivir on the Internet or from vendors outside of the United States. Medications distributed from Internet sales may contain dangerous ingredients, or may not be distributed by a licensed pharmacy. Samples of "Tamiflu" purchased on the Internet have been found to contain cloxacillin, a type of antibiotic that can have dangerous side effects in people who are allergic to penicillin. For more information, contact the U.S. Food and Drug Administration (FDA) or visit www.fda.gov/buyonlineguide.

Oseltamivir may also be used for purposes not listed in this medication guide.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Do not use a nasal flu vaccine (FluMist) within 48 hours after taking oseltamivir. Oseltamivir may interfere with the drug action of FluMist, making the vaccine less effective. Follow your doctor's instructions.

Storage

Oral

25°C (may be exposed to 15–30°C).1

25°C (may be exposed to 15–30°C).1

Following reconstitution, store suspension at 2–8°C for up to 17 days.1 Alternatively, may be stored for up to 10 days at 25°C (may be exposed to 15–30°).1 Do not freeze.1

Extemporaneous oral suspensions prepared according to manufacturer's directions using 75-mg oseltamivir capsules and simple syrup, cherry syrup vehicle, or Ora-Sweet SF are stable for 5 weeks (35 days) at 2–8°C or 5 days at 25°C.1

Oseltamivir belongs to the family of medicines called antivirals, which are used to treat infections caused by viruses. Oseltamivir is used in the treatment of the infection caused by the flu virus (influenza A and influenza B). Oseltamivir may also be used to prevent and treat swine influenza A.

Oseltamivir may reduce flu symptoms (weakness, headache, fever, cough, runny or stuffy nose, and sore throat) by 1 day. Oseltamivir is also used to prevent influenza infection if you have come into close contact with someone who has the flu.

If you receive the flu vaccine every year, continue to do so. Oseltamivir is not a substitute for your yearly flu shot.

This medicine is available only with your doctor's prescription.

It is very important that your doctor check your or your child's progress after treatment. This is to make sure that the infection is cleared up completely, and to allow your doctor to check for any unwanted effects.

This medicine is not a substitute for an annual flu shot. It also will not keep you or your child from getting a bacterial infection that starts with flu-like symptoms.

This medicine may cause a serious type of allergic reaction called anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you or your child are using this medicine.

Serious skin reactions can occur with this medicine. Stop using this medicine and check with your doctor right away if you have blistering, peeling, or loosening of the skin, red skin lesions, severe acne or skin rash, sores or ulcers on the skin, or fever or chills while you or your child are using this medicine.

Oseltamivir may cause some people, especially children and teenagers, to be agitated, irritable, or display other abnormal behaviors, which may result in injury. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child's doctor right away.

Make sure your doctor knows if you or your child plan to get the live nasal mist flu vaccine before you start using this medicine. You should not receive the vaccine within 2 weeks before or 48 hours after using this medicine.

If your or your child's symptoms do not improve after you or your child finish taking the medicine, or if they become worse, check with your doctor.

Dosage and Administration Overview

Administer Tamiflu for the treatment of influenza in patients 2 weeks of age or older [see Dosage and Administration (2.2)] or for prophylaxis of influenza in patients 1 year and older [see Dosage and Administration (2.3)] using:

• Tamiflu capsules or
• Tamiflu for oral suspension (supplied as a powder). This is the preferred formulation (6 mg per mL) for patients who cannot swallow capsules. Prior to use, the supplied Tamiflu powder must be constituted with water by the pharmacist to produce the oral suspension [see Dosage and Administration (2.5)].

The capsules and oral suspension may be taken with or without food; however, tolerability may be enhanced if Tamiflu is taken with food.

Adjust the Tamiflu dosage in patients with moderate or severe renal impairment [see Dosage and Administration (2.4)].

For patients who cannot swallow capsules, Tamiflu for oral suspension is the preferred formulation. When Tamiflu for oral suspension is not available from wholesaler or the manufacturer, Tamiflu capsules may be opened and mixed with sweetened liquids such as regular or sugar-free chocolate syrup, corn syrup, caramel topping, or light brown sugar (dissolved in water). During emergency situations and when neither the oral suspension or the age-appropriate strengths of Tamiflu capsules to mix with sweetened liquids are available, then a pharmacist may prepare an emergency supply of oral suspension from Tamiflu 75 mg capsules [see Dosage and Administration (2.6)].

Recommended Dosage for Treatment of Influenza

Initiate treatment with Tamiflu within 48 hours of influenza symptom onset.

Adults and Adolescents (13 years of age and older)

The recommended oral dosage of Tamiflu for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily (one 75 mg capsule or 12.5 mL of oral suspension twice daily) for 5 days.

Pediatric Patients (2 weeks of age through 12 years of age)

Table 1 displays the recommended oral dosage of Tamiflu for treatment of influenza in pediatric patients 2 weeks of age through 12 years of age and provides information about prescribing the capsule or the formulation for oral suspension.

Recommended Dosage for Prophylaxis of Influenza

Initiate post-exposure prophylaxis with Tamiflu within 48 hours following close contact with an infected individual. Initiate seasonal prophylaxis with Tamiflu during a community outbreak.

Adults and Adolescents (13 years of age and older)

The recommended dosage of Tamiflu for prophylaxis of influenza in adults and adolescents 13 years and older is 75 mg orally once daily (one 75 mg capsule or 12.5 mL of oral suspension once daily) for at least 10 days following close contact with an infected individual and up to 6 weeks during a community outbreak. In immunocompromised patients, Tamiflu may be continued for up to 12 weeks [see Use in Specific Populations (8.9)]. The duration of protection lasts for as long as Tamiflu dosing is continued.

Pediatric Patients (1 year to 12 years of age)

Table 1 displays the recommended oral dosage of Tamiflu for prophylaxis of influenza in pediatric patients 1 year to 12 years of age based on body weight and provides information about prescribing the capsule or the formulation for oral suspension. Prophylaxis in pediatric patients is recommended for 10 days following close contact with an infected individual and up to 6 weeks during a community outbreak [see Use in Specific Populations (8.4) and Clinical Studies (14.2)].

Dosage in Patients with Renal Impairment

Table 2 displays the dosage recommendations for the treatment and prophylaxis of influenza in adults with various stages of renal impairment (estimated creatinine clearance of less than or equal to 90 mL per minute). Dosage modifications are recommended in adults with an estimated creatinine clearance less than or equal to 60 mL per minute [see Use in Specific Population (8.6) and Clinical Pharmacology (12.3)].

Preparation and Storage of Constituted Tamiflu Oral Suspension

Prior to dispensing to the patient, constitute Tamiflu for oral suspension (supplied as powder):

Emergency Preparation of Oral Suspension from 75 mg Tamiflu Capsules

The following directions are provided for use only during emergency situations and when FDA-approved, commercially manufactured Tamiflu for oral suspension is not available from wholesalers or the manufacturer.

The following emergency preparation instructions will provide one patient with enough Tamiflu for a 5-day course of treatment of influenza or a 10-day course of prophylaxis of influenza:

Step #1: Determine the dosage of Tamiflu for the patient [see Dosage and Administration (2.2, 2.3, and 2.4)] then determine the total volume of oral suspension needed to be prepared (see Table 3).

Step #2: Preparation must be performed with only one of the following vehicles (other vehicles have not been studied): Cherry Syrup (Humco®), Ora-Sweet® SF (sugar-free) (Paddock Laboratories), or simple syrup. Determine the number of capsules and the amount of water and vehicle needed to prepare the total volume (see Table 3) of prepared oral suspension (6 mg per mL) for a complete treatment or prophylaxis course (see Table 4).

Step #3: Follow the instructions below for preparing the 75 mg Tamiflu capsules to produce the oral suspension (6 mg per mL):

1. Place the specified amount of water into a polyethyleneterephthalate (PET) or glass bottle (see Table 4). Constitution in other bottle types is not recommended because there is no stability data with other bottle types.
2. Carefully separate the capsule body and cap and pour the contents of the required number of Tamiflu 75 mg capsules into the PET or glass bottle.
3. Gently swirl the suspension to ensure adequate wetting of the Tamiflu powder for at least 2 minutes.
4. Slowly add the specified amount of vehicle to the bottle.
5. Close the bottle using a child-resistant cap and shake well for 30 seconds to completely dissolve the active drug and to ensure homogeneous distribution of the dissolved drug in the resulting suspension. The active drug, oseltamivir phosphate, readily dissolves in the specified vehicles. The suspension is caused by inert ingredients of Tamiflu capsules which are insoluble in these vehicles.
6. Put an ancillary label on the bottle indicating "Shake Well Before Use."
7. Instruct the parent or caregiver that any unused suspension remaining in the bottle following completion of therapy must be discarded by either affixing an ancillary label to the bottle or adding a statement to the pharmacy label instructions.
8. Place a pharmacy label on the bottle that includes the patient's name, dosing instructions, drug name and any other required information to be in compliance with all State and Federal Pharmacy Regulations. Place an appropriate expiration date on the label according to storage conditions below.
9. Include the recommended dosage on the pharmacy label as per Tables 1 and 2 [see Dosage and Administration (2.2, 2.3, and 2.4)].
10. Store the prepared oral suspension in glass or PET bottles either:
    • In a refrigerator [2° to 8°C (36° to 46°F)]: Stable for 5 weeks when stored in a refrigerator.
    • At room temperature [25°C (77°F)]: Stable for 5 days when stored at room temperature.

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)]

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 Tamiflu 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. The majority of these adverse reactions were reported on a single occasion, occurred on either the first or second treatment day and resolved spontaneously within 1-2 days. This summary includes otherwise healthy adults/adolescents and subjects "at risk" (subjects at higher risk of developing complications associated with influenza, e.g., elderly patients and patients with chronic cardiac or respiratory disease). In general, the safety profile in the subjects "at risk" was qualitatively similar to that in otherwise healthy adults/adolescents.

Adverse Reactions from Treatment and Prophylaxis Trials in Pediatric Subjects (1 year to 12 years of age)

A total of 1,481 pediatric subjects (including otherwise healthy pediatric subjects aged 1 year to 12 years and asthmatic pediatric subjects aged 6 to 12 years) participated in clinical trials of Tamiflu for the treatment of influenza. A total of 859 pediatric subjects received treatment with Tamiflu for oral suspension either at a 2 mg per kg twice daily for 5 days or weight-band dosing. Vomiting was the only adverse reaction reported at a frequency of >1% in subjects receiving Tamiflu (16%) compared to placebo (8%).

Amongst the 148 pediatric subjects aged 1 year to 12 years who received Tamiflu at doses of 30 to 60 mg once daily for 10 days in a post-exposure prophylaxis study in household contacts (n = 99), and in a separate 6–week seasonal influenza prophylaxis safety study (n = 49), vomiting was the most frequent adverse reaction (8% on Tamiflu versus 2% in the no prophylaxis group).

Adverse Reactions from Treatment Trials in Pediatric Subjects (2 weeks to less than 1 year of age)

Assessment of adverse reactions in pediatric subjects 2 weeks to less than 1 year of age was based on two open-label studies that included safety data on 135 influenza-infected subjects 2 weeks to less than 1 year of age (including premature infants at least 36 weeks post conceptional age) exposed to Tamiflu at doses ranging from 2 to 3.5 mg per kg of the formulation for oral suspension twice daily orally for 5 days. The safety profile of Tamiflu was similar across the age range studied, with vomiting (9%), diarrhea (7%) and diaper rash (7%) being the most frequently reported adverse reactions, and was generally comparable to that observed in older pediatric and adult subjects.

Adverse Reactions from the Prophylaxis Trial in Immunocompromised Subjects

In a 12-week seasonal prophylaxis study in 475 immunocompromised subjects, including 18 pediatric subjects 1 year to 12 years of age, the safety profile in the 238 subjects receiving Tamiflu 75 mg once daily was consistent with that previously observed in other Tamiflu prophylaxis clinical trials [see Clinical Studies (14.2)].

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of Tamiflu. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to Tamiflu exposure.

General disorders and administration site conditions: Swelling of the face or tongue, allergy, anaphylactic/anaphylactoid reactions, hypothermia

Skin and subcutaneous tissue disorders: Rash, dermatitis, urticaria, eczema, toxic epidermal necrolysis, Stevens-Johnson Syndrome, erythema multiforme [see Warnings and Precautions (5.1)]

Gastrointestinal Disorders: Gastrointestinal bleeding, hemorrhagic colitis

Cardiac Disorders: Arrhythmia

Hepatobiliary Disorders: Hepatitis, abnormal liver function tests

Nervous System Disorders: Seizure

Metabolism and Nutrition Disorders: Aggravation of diabetes

Psychiatric Disorders: Abnormal behavior, delirium, including symptoms such as hallucinations, agitation, anxiety, altered level of consciousness, confusion, nightmares, delusions [see Warnings and Precautions (5.2)]

Treatment of Influenza

Adults

Two randomized, placebo-controlled, double-blind clinical trials of Tamiflu were conducted in adults between 18 and 65 years old, one in the U.S. and one outside the U.S., for the treatment of acute uncomplicated influenza. Eligible subjects had fever of at least 100ºF, accompanied by at least one respiratory symptom (cough, nasal symptoms, or sore throat) and at least one systemic symptom (myalgia, chills/sweats, malaise, fatigue, or headache), and influenza virus was known to be circulating in the community. Subjects were randomized to receive oral Tamiflu or placebo for 5 days. All enrolled subjects were allowed to take fever-reducing medications.

Of 1,355 subjects enrolled in these two trials, 849 (63%) subjects were influenza-infected (median age 34 years; 52% male; 90% Caucasian; 31% smokers). Of the 849 influenza-infected subjects, 95% were infected with influenza A, 3% with influenza B, and 2% with influenza of unknown type.

Study medication was started within 40 hours of onset of symptoms and administered twice daily for 5 days. Subjects were required to self-assess the influenza-associated symptoms (nasal congestion, sore throat, cough, aches, fatigue, headaches, and chills/sweats) twice daily as "none," "mild," "moderate," or "severe". Time to improvement was calculated from the time of treatment initiation to the time when all symptoms were assessed as "none" or "mild". In both trials, there was a 1.3-day reduction in the median time to improvement in influenza-infected subjects who received Tamiflu 75 mg twice a day for 5 days compared to subjects who received placebo. Subgroup analyses by gender showed no differences in the treatment effect of Tamiflu in men and women.

In the treatment of influenza, no increased efficacy was demonstrated in subjects who received higher doses of Tamiflu.

Adolescents and Adults with Chronic Cardiac or Respiratory Disease

A double-blind, placebo-controlled, multicenter trial was unable to demonstrate efficacy of Tamiflu (75 mg twice daily for 5 days) in the treatment of influenza in adult and adolescent subjects (13 years or older) with chronic cardiac (excluding chronic idiopathic hypertension) or respiratory diseases, as measured by time to alleviation of all symptoms. However, in patients treated with Tamiflu there was a more rapid cessation of febrile illness. No difference in the incidence of influenza complications was observed between the treatment and placebo groups in this population.

Geriatric Subjects

Three double-blind placebo-controlled treatment trials were conducted in subjects who were at least 65 years of age in three consecutive seasons. The enrollment criteria were similar to that of adult trials with the exception of fever being defined as higher than 97.5°F. Of 741 subjects enrolled, 476 (65%) subjects were influenza-infected; of these, 95% were infected with influenza type A and 5% with influenza type B.

In the pooled analysis, there was a 1-day reduction in the median time to improvement in influenza-infected subjects who received Tamiflu 75 mg twice daily for 5 days compared to those who received placebo (p=NS) [see Use in Specific Populations (8.5)]. Some seasonal variability was noted in the clinical efficacy outcomes.

Pediatric Subjects (1 year to 12 years of age)

One double-blind placebo-controlled treatment trial was conducted in pediatric subjects aged 1 year to 12 years (median age 5 years) who had fever (at least 100ºF) plus one respiratory symptom (cough or coryza) when influenza virus was known to be circulating in the community. Of 698 subjects enrolled in this trial, 452 (65%) were influenza-infected (50% male; 68% Caucasian). Of the 452 influenza-infected subjects, 67% were infected with influenza A and 33% with influenza B.

Efficacy in this trial was determined by the time to alleviation or resolution of influenza signs and symptoms, measured by a composite endpoint that required the following four individual conditions be met: i) alleviation of cough, ii) alleviation of coryza, iii) resolution of fever, and iv) parental opinion of a return to normal health and activity. Tamiflu treatment of 2 mg per kg twice daily, started within 48 hours of onset of symptoms, reduced the total composite time to freedom from illness by 1.5 days compared to placebo. Subgroup analyses by gender showed no differences in the treatment effect of Tamiflu in male and female pediatric subjects.

Pediatric Subjects (2 weeks to less than 1 year of age)

Two open-label trials evaluated the safety and pharmacokinetics of oseltamivir and oseltamivir carboxylate in influenza-infected pediatric subjects 2 weeks to less than 1 year of age (including premature infants at least 36 weeks post conceptional age). Subjects received Tamiflu at doses ranging from 2 to 3.5 mg per kg twice daily for 5 days depending on subject age. These clinical trials were not designed to evaluate clinical efficacy or virologic response.

Of the 136 subjects under the age of 1 year enrolled and dosed in the trials, the majority of the subjects were male (55%), white (79%), non-Hispanic (74%), full term (76%) and infected with influenza A (80%). Pharmacokinetic data indicated that a dose of 3 mg per kg twice daily in pediatric subjects 2 weeks to less than 1 year of age provided Tamiflu concentrations similar to or higher than those observed in older pediatric subjects and adults receiving the approved dose and provided the basis for approval [see Adverse Reactions (6.1) and Use in Specific Populations (8.4)].

Prophylaxis of Influenza

Adult and Adolescent Subjects (13 years of age and older)

The efficacy of Tamiflu in preventing naturally occurring influenza illness has been demonstrated in three seasonal prophylaxis (community outbreak) clinical trials and one post-exposure prophylaxis trial in household contacts. The efficacy endpoint for all of these trials was the incidence of laboratory-confirmed clinical influenza defined as meeting all the following criteria (all signs and symptoms must have been recorded within 24 hours):

• oral temperature greater than or equal to 99.0ºF (37.2ºC),
• at least one respiratory symptom (cough, sore throat, nasal congestion),
• at least one constitutional symptom (aches and pain, fatigue, headache, chills/sweats), and
• either a positive virus isolation or a four-fold increase in virus antibody titers from baseline.

In a pooled analysis of two seasonal prophylaxis trials in healthy unvaccinated adults (aged 18 to 65 years), Tamiflu 75 mg once daily taken for 42 days during a community outbreak reduced the incidence of laboratory-confirmed clinical influenza from 5% (25/519) for the placebo group to 1% (6/520) for the Tamiflu group.

In the seasonal (community outbreak) prophylaxis trial in elderly residents of skilled nursing homes, about 80%, 43%, and 14% of the subjects were vaccinated, had cardiac disorders, and had chronic airway obstructive disorders, respectively. In this trial, subjects were randomized to Tamiflu 75 mg once daily or placebo taken orally for 42 days. The incidence of laboratory-confirmed clinical influenza was 4% (12/272) in the placebo-treated subjects compared to less than 1% (1/276) in the Tamiflu-treated subjects.

In the post-exposure prophylaxis trial in household contacts (aged 13 years or older) of an index influenza case, Tamiflu 75 mg once daily or placebo taken orally was administered within 48 hours of onset of symptoms in the index case and continued for 7 days (index cases did not receive Tamiflu treatment). The incidence of laboratory-confirmed clinical influenza was 12% (24/200) in the placebo-treated subjects compared to 1% (2/205) in the Tamiflu-treated subjects.

Pediatric Subjects (1 year to 12 years of age)

The efficacy of Tamiflu in preventing naturally occurring influenza illness was demonstrated in a randomized, open-label post-exposure prophylaxis trial in household contacts that included pediatric subjects aged 1 year to 12 years, both as index cases and as family contacts. All index cases in this trial received Tamiflu for oral suspension 30 to 60 mg taken orally once daily for 10 days. The efficacy parameter was the incidence of laboratory-confirmed clinical influenza in the household. Laboratory-confirmed clinical influenza was defined as meeting all of the following criteria:

• oral temperature at least 100°F (37.8°C),
• cough and/or coryza recorded within 48 hours, and
• either a positive virus isolation or a four-fold or greater increase in virus antibody titers from baseline or at illness visits.

Among household contacts 1 year to 12 years of age not already shedding virus at baseline, the incidence of laboratory-confirmed clinical influenza was lower in the group who received Tamiflu prophylaxis [3% (3/95)] compared to the group who did not receive Tamiflu prophylaxis [17% (18/106)].

Immunocompromised Subjects

A double-blind, placebo-controlled trial was conducted for seasonal prophylaxis of influenza in 475 immunocompromised subjects (including 18 pediatric subjects 1 year to 12 years of age) who had received solid organ (n=388; liver, kidney, liver and kidney) or hematopoietic stem cell transplants (n=87). Median time since transplant for solid organ transplant recipients was 1,105 days for the placebo group and 1,379 days for the Tamiflu group. Median time since transplant for hematopoietic stem cell transplant recipients was 424 days for the placebo group and 367 days for the Tamiflu group. Approximately 40% of subjects received influenza vaccine prior to entering the study. The primary efficacy endpoint was the incidence of confirmed clinical influenza, defined as oral temperature higher than 99.0°F (37.2°C) plus cough and/or coryza, all recorded within 24 hours, plus either a positive virus culture or a four-fold increase in virus antibody titers from baseline. Subjects received treatment with Tamiflu 75 mg or placebo once daily by mouth for 12 weeks. The incidence of confirmed clinical influenza was 3% (7/238) in the placebo group compared with 2% (5/237) in the Tamiflu group; this difference was not statistically significant. A secondary analysis was performed using the same clinical symptoms and RT-PCR for laboratory confirmation of influenza infection. Among subjects who were not already shedding virus at baseline, the incidence of RT-PCR-confirmed clinical influenza infection was 3% (7/231) in the placebo group and <1% (1/232) in the Tamiflu group.

Tamiflu (oseltamivir) is an antiviral medication that blocks the actions of influenza virus types A and B in your body.

Tamiflu is used to treat influenza in people 2 weeks of age and older who have had flu symptoms for 2 days or less. Oseltamivir may also be given to prevent influenza in people who are at least 1 year old, who may be exposed but do not yet have symptoms. Tamiflu will not treat the common cold.

Tamiflu may also be used for purposes not listed in this medication guide.

Take the missed dose as soon as you remember. Skip the missed dose if your next dose is less than 2 hours away. Do not take extra medicine to make up the missed dose.