In this drug factsheet:
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- abdominal pain
- trouble sleeping
Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- signs of liver damage (e.g., yellowing of skin or whites of eyes, abdominal pain, loss of appetite, dark urine, light-coloured stools, tiredness, or weakness)
Stop taking the medication and seek immediate medical attention if any of the following occur:
- delirium, confusion, abnormal behavior leading to self-injury, delusions, hallucinations, agitation, anxiety, nightmares
- symptoms of a severe allergic reaction such as rash, itching, flushing, swelling, breathing difficulties, facial edema, and dizziness
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Effectiveness: The benefit of oseltamivir has not been evaluated for the treatment of flu symptoms that have been present for more than 2 days.
Flu shots: Oseltamivir is not a substitute for the flu shot. Continue to receive an annual flu shot as advised by your doctor.
Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Oseltamivir may also cause decreased liver function, and liver failure in rare cases. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.
Neurological effects: There have been rare reports of people who have experienced neurological and psychological problems while taking oseltamivir. These included hallucinations, delusions, delirium, abnormal behaviour, and self-injury. If you experience any of these symptoms, seek immediate medical attention. If you have any concerns about this medication, contact your doctor.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if oseltamivir passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding. Mothers who are breast-feeding children under one year old should not take this medication.
Children: The safety and effectiveness of using this medication have not been established for children under one year of age.
What other drugs could interact with this medication?
There may be an interaction between oseltamivir and any of the following:
- influenza virus nasal spray vaccine
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.