Tamiflu 45mg Capsules
It is used to treat or prevent the flu. It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antiviral
Pharmacologic Class
Neuraminidase Inhibitor
Pregnancy Category
Not available
FDA Approved
Oct 1999
DEA Schedule
Not Controlled
Overview
What is this medicine?
Tamiflu is an antiviral medicine used to treat or prevent the flu (influenza). It works by stopping the flu virus from spreading in your body. It's most effective when started soon after flu symptoms begin.
How to Use This Medicine
Taking Your Medication
To take this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes stomach upset, take it with food to help minimize discomfort. Continue taking this medication as directed by your doctor or healthcare provider, even if you start feeling better.
If you have difficulty swallowing the medication, consult your doctor. In some cases, your doctor may advise you to mix the capsule contents with a sweet liquid, such as chocolate syrup, caramel topping, corn syrup, or light brown sugar dissolved in water. Alternatively, a liquid suspension can be prepared from the capsules if needed; discuss this option with your doctor or pharmacist.
Storing and Disposing of Your Medication
Store this medication at room temperature in a dry place, avoiding storage in a bathroom. If a liquid suspension is prepared from the capsules, refrigerate it and do not freeze. Discard any unused portion after 35 days if stored in the refrigerator. If you choose to store it at room temperature, discard any unused portion after 5 days. Keep all medications in a safe location, out of the reach of children and pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose (less than 2 hours), skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To take this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes stomach upset, take it with food to help minimize discomfort. Continue taking this medication as directed by your doctor or healthcare provider, even if you start feeling better.
If you have difficulty swallowing the medication, consult your doctor. In some cases, your doctor may advise you to mix the capsule contents with a sweet liquid, such as chocolate syrup, caramel topping, corn syrup, or light brown sugar dissolved in water. Alternatively, a liquid suspension can be prepared from the capsules if needed; discuss this option with your doctor or pharmacist.
Storing and Disposing of Your Medication
Store this medication at room temperature in a dry place, avoiding storage in a bathroom. If a liquid suspension is prepared from the capsules, refrigerate it and do not freeze. Discard any unused portion after 35 days if stored in the refrigerator. If you choose to store it at room temperature, discard any unused portion after 5 days. Keep all medications in a safe location, out of the reach of children and pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose (less than 2 hours), skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take with food to reduce stomach upset (nausea/vomiting).
- Complete the full course of medication, even if you start feeling better.
- This medication is not a substitute for the annual flu vaccine. Continue to get vaccinated as recommended.
- Practice good hygiene (hand washing, covering coughs/sneezes) to prevent spread of flu.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
Treatment: 75 mg twice daily for 5 days. Prophylaxis: 75 mg once daily for at least 10 days (community outbreak) or up to 6 weeks (seasonal).
Dose Range:
75 - 75 mg
Condition-Specific Dosing:
treatment:
75 mg BID for 5 days, initiated within 48 hours of symptom onset.
prophylaxis:
75 mg QD for at least 10 days (post-exposure) or up to 6 weeks (seasonal).
Pediatric Dosing
Neonatal:
Treatment (2 weeks to <1 year): 3 mg/kg twice daily for 5 days. Prophylaxis: Not routinely recommended for infants <1 year.
Infant:
Treatment (2 weeks to <1 year): 3 mg/kg twice daily for 5 days. Prophylaxis: Not routinely recommended for infants <1 year.
Child:
Treatment (1 to 12 years): Weight-based dosing (e.g., 15 kg to 23 kg: 45 mg BID; 23 kg to 40 kg: 60 mg BID; >40 kg: 75 mg BID) for 5 days. Prophylaxis (1 to 12 years): Weight-based dosing (e.g., 15 kg to 23 kg: 45 mg QD; 23 kg to 40 kg: 60 mg QD; >40 kg: 75 mg QD) for 10 days.
Adolescent:
Treatment (>13 years): 75 mg twice daily for 5 days. Prophylaxis (>13 years): 75 mg once daily for at least 10 days.
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed (CrCl > 60 mL/min).
Moderate:
Treatment (CrCl 31-60 mL/min): 75 mg once daily for 5 days. Prophylaxis (CrCl 31-60 mL/min): 75 mg every other day.
Severe:
Treatment (CrCl 10-30 mL/min): 75 mg once daily for 5 days. Prophylaxis (CrCl 10-30 mL/min): 75 mg every other day.
Dialysis:
Hemodialysis: Treatment: 75 mg after each hemodialysis session. Prophylaxis: 75 mg after every other hemodialysis session. CAPD: Treatment: 75 mg once, then 30 mg once daily for 5 days. Prophylaxis: 30 mg once daily.
Hepatic Impairment:
Mild:
No adjustment needed.
Moderate:
No adjustment needed.
Severe:
No adjustment needed.
Pharmacology
Mechanism of Action
Oseltamivir phosphate is a prodrug that is metabolized to oseltamivir carboxylate, an active neuraminidase inhibitor. Neuraminidase is a viral enzyme essential for viral replication and release of new virions from infected cells and for further spread of infectious virus in the body. Oseltamivir carboxylate inhibits influenza A and B virus neuraminidase, thereby preventing the release of new virions from infected cells and reducing the spread of the virus.
Pharmacokinetics
Absorption:
Bioavailability:
80% (of oseltamivir carboxylate from oseltamivir phosphate)
Tmax:
3-4 hours (for oseltamivir carboxylate)
FoodEffect:
Food does not significantly affect absorption, but may reduce gastrointestinal intolerance.
Distribution:
Vd:
23 L (oseltamivir carboxylate)
ProteinBinding:
3% (oseltamivir carboxylate)
CnssPenetration:
Limited
Elimination:
HalfLife:
6-10 hours (oseltamivir carboxylate)
Clearance:
Not available
ExcretionRoute:
Renal (primarily as oseltamivir carboxylate)
Unchanged:
Not available (oseltamivir carboxylate is the primary excreted form)
Pharmacodynamics
OnsetOfAction:
Not precisely defined, clinical benefit seen within 12-24 hours of initiation.
PeakEffect:
Not precisely defined, related to viral load reduction.
DurationOfAction:
Approximately 12 hours (based on BID dosing).
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Neurological problems, particularly if you have the flu, including:
+ Confusion
+ Changes in behavior
+ Speech problems
+ Shakiness
+ Seizures
+ Hallucinations (more common in children)
A severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis), characterized by:
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Red or irritated eyes
+ Sores in your mouth, throat, nose, or eyes
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor:
Diarrhea
Upset stomach
Vomiting
* Headache
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Neurological problems, particularly if you have the flu, including:
+ Confusion
+ Changes in behavior
+ Speech problems
+ Shakiness
+ Seizures
+ Hallucinations (more common in children)
A severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis), characterized by:
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Red or irritated eyes
+ Sores in your mouth, throat, nose, or eyes
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor:
Diarrhea
Upset stomach
Vomiting
* Headache
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe allergic reactions (rash, hives, swelling of face/lips/tongue, difficulty breathing)
- Sudden confusion, delirium, hallucinations, unusual behavior (especially in children and adolescents)
- Worsening flu symptoms or development of new symptoms (e.g., difficulty breathing, chest pain, severe vomiting)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have kidney disease, as this may affect your ability to take this medication.
This list is not exhaustive, and it is crucial to discuss all your medications, health conditions, and concerns with your doctor. This includes:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Any health problems you have, as they may interact with this medication
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have kidney disease, as this may affect your ability to take this medication.
This list is not exhaustive, and it is crucial to discuss all your medications, health conditions, and concerns with your doctor. This includes:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Any health problems you have, as they may interact with this medication
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
This medication is not a substitute for a flu shot. If your doctor has recommended that you receive a flu shot, it is crucial that you follow their advice and get vaccinated. This medication is specifically designed to treat the flu, not the common cold.
Additionally, taking this medication will not prevent you from spreading the flu to others.
Before receiving a flu vaccine, discuss the timing with your doctor, especially if you have recently taken this medication. Conversely, if you have recently received a flu vaccine, consult with your doctor before starting this medication.
If you are pregnant, planning to become pregnant, or are breastfeeding, it is vital to discuss the potential benefits and risks of this medication with your doctor, as this will help you make an informed decision about your treatment and the well-being of your baby.
This medication is not a substitute for a flu shot. If your doctor has recommended that you receive a flu shot, it is crucial that you follow their advice and get vaccinated. This medication is specifically designed to treat the flu, not the common cold.
Additionally, taking this medication will not prevent you from spreading the flu to others.
Before receiving a flu vaccine, discuss the timing with your doctor, especially if you have recently taken this medication. Conversely, if you have recently received a flu vaccine, consult with your doctor before starting this medication.
If you are pregnant, planning to become pregnant, or are breastfeeding, it is vital to discuss the potential benefits and risks of this medication with your doctor, as this will help you make an informed decision about your treatment and the well-being of your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Headache
- Tremor
- Seizures (rare)
What to Do:
Seek immediate medical attention or call Poison Control at 1-800-222-1222. Treatment is supportive.
Drug Interactions
Moderate Interactions
- Live attenuated influenza vaccine (LAIV)
Minor Interactions
- Probenecid
Monitoring
Routine Monitoring
Clinical symptoms of influenza
Frequency: Daily during treatment
Target: Resolution or improvement of symptoms
Action Threshold: Lack of improvement or worsening symptoms may indicate treatment failure or complications.
Renal function (CrCl)
Frequency: Prior to initiation in patients with suspected renal impairment
Target: Not applicable
Action Threshold: Adjust dose if CrCl ⤠60 mL/min.
Symptom Monitoring
- Improvement in fever
- Reduction in cough
- Decrease in body aches
- Resolution of headache
- Monitoring for neuropsychiatric events (e.g., confusion, delirium, hallucinations, self-injury) especially in pediatric patients.
Special Patient Groups
Pregnancy
Oseltamivir is generally considered acceptable for use during pregnancy when clinically indicated, as the benefits of treating influenza in pregnant women (who are at higher risk for complications) typically outweigh potential risks. Data from observational studies and registries have not shown an increased risk of major birth defects or adverse pregnancy outcomes.
Trimester-Specific Risks:
First Trimester:
Limited data, but no clear evidence of increased risk of major birth defects.
Second Trimester:
No clear evidence of increased risk.
Third Trimester:
No clear evidence of increased risk.
Lactation
Oseltamivir and its active metabolite are excreted in human milk in low amounts. The amount ingested by a breastfed infant is expected to be very low and unlikely to cause adverse effects. Benefits of breastfeeding and the mother's clinical need for oseltamivir should be considered.
Infant Risk:
Low risk (L3 - Moderately Safe).
Pediatric Use
Approved for treatment of influenza in patients 2 weeks of age and older, and for prophylaxis in patients 1 year of age and older. Dosing is weight-based for younger children. Close monitoring for neuropsychiatric events is recommended, though causality is not established.
Geriatric Use
No specific dose adjustment is required based on age alone. However, dose adjustments are necessary for elderly patients with renal impairment, as renal function often declines with age.
Clinical Information
Clinical Pearls
- Oseltamivir is most effective when initiated within 48 hours of influenza symptom onset for treatment.
- It is not a substitute for the annual influenza vaccine.
- Can be taken with or without food, but taking with food may improve tolerability and reduce GI upset.
- Patients should be advised to complete the full 5-day course of treatment, even if symptoms improve.
- Rare but serious neuropsychiatric events (e.g., delirium, hallucinations) have been reported, primarily in pediatric patients, though a causal link has not been definitively established. Patients should be monitored for unusual behavior.
Alternative Therapies
- Zanamivir (Relenza) - inhaled neuraminidase inhibitor
- Peramivir (Rapivab) - intravenous neuraminidase inhibitor
- Baloxavir marboxil (Xofluza) - cap-dependent endonuclease inhibitor
Cost & Coverage
Average Cost:
Varies, check current pricing per 10 capsules (treatment course)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (generic), Tier 3 (brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist. If you have any questions or concerns about this medication, don't hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.