See also: [[Influenza]] ## General considerations Treatment of influenza with a neuraminidase inhibitor, such as oseltamivir or zanamivir, has been associated with fewer complications, hospital admissions and deaths due to influenza in systematic reviews of observational studies. These studies included people at high risk of severe influenza or mortality due to influenza. By contrast, systematic reviews of randomised controlled trials did not demonstrate such benefits; however, these studies largely recruited healthy, low-risk adults and were underpowered to detect important outcomes such as hospitalisation and mortality. In otherwise healthy adults who have a low risk of complications, treatment with a neuraminidase inhibitor reduces duration of influenza symptoms by less than 1 day on average, when treatment is started within 48 hours of symptom onset. Such limited benefit must be balanced against the potential adverse effects of antiviral treatment, including nausea, vomiting, headaches and neuropsychiatric events. ### renal impairment - pts with unknown or known normal renal f(x) can be started on oseltamivir - Only need to measure renal function at time of prescribing if expected drop in renal function ***Dose in renal impairment:*** - GFR >30 → normal dose - GFR 10-30 → ppx q48 hours for 10 days - GRR <10 → if essential ppx, 30mg q48 hours for 10 days ### pregnancy TGA B1 → generally considered safe for pregnancy (see [pregnancy medication guide](https://avicennamd.org/pregnancyMedications/?medicine=Oseltamivir) ) Pregnant women are at ↑ risk for serious influenza illness and adverse foetal outcomes ### breast feeding Considered safe during breast feeding ## Adverse effects - nausea and vomiting most common. *Reduced by taking medication with food* - rare Neuropsychiatric effects: vivid dreams, headaches, dizziness. ## Indications Regardless of the duration of symptoms, **offer treatment** to patients: - with established complications - who need to be admitted to hospital for management of influenza (see also Additional considerations in severe influenza) - with moderate-severity or high-severity community-acquired pneumonia, during the influenza season. **Consider treatment** for individuals at higher risk of poor outcomes from influenza (see list below), despite equivocal data to support benefit. Antiviral therapy is recommended for **pregnant women** after discussion of the benefits and harms of therapy, because of the higher risk of poor outcomes from influenza in pregnancy (for information on Australian categorisation of drugs in pregnancy, see Pregnancy and breastfeeding). Use of antivirals outside of the higher-risk groups listed in below list is not recommended, except to prevent disease transmission in some circumstances. ***Individuals at higher risk for poor outcomes feom influenza:*** The following groups of individuals are at higher risk of poor outcomes from influenza (eg complications, severe influenza, hospitalisation, death): - adults aged 65 years or older - pregnant women - people with the following conditions: - heart disease - Down syndrome - obesity (BMI 30 kg/m2 or more) - chronic respiratory conditions - severe neurological conditions - immune compromise - other chronic illnesses - Aboriginal and Torres Strait Islander people of any age - children aged 5 years or younger - residents of aged-care facilities or long-term residential facilities - homeless people. ### Treatment to prevent disease transmission Treatment with neuraminidase inhibitors may reduce the risk of viral shedding and disease transmission. Consider treatment for patients with influenza who: - are in hospital or are residents of an aged-care facility - have household contacts that are at higher risk of poor outcomes from influenza ## Dose *oseltamivir* orally, 12-hourly for 5 days    adult: 75 mg child younger than 1 year: 3 mg/kg child 1 year or older and less than 15 kg: 30 mg child 1 year or older and 15 to 23 kg: 45 mg child 1 year or older and 23 to 40 kg: 60 mg child 1 year or older and more than 40 kg: 75 mg ### post-exposure prophlaxis Neuraminidase inhibitors can be used for postexposure prophylaxis of influenza when vaccination is contraindicated, or when the circulating strain is not covered by the annual vaccine. *Start postexposure prophylaxis as soon as possible after exposure, within 48 hours.* Consider postexposure prophylaxis for **individuals at higher risk of poor outcomes from influenza** (see list abovr). Additionally, postexposure prophylaxis is appropriate for some people (eg patients in hospital, *healthcare workers*) to prevent transmission after unprotected exposure to influenza. It can also be used to manage influenza outbreaks in institutions (eg hospitals, aged-care facilities). If postexposure prophylaxis for influenza is indicated, use: 1 oseltamivir orally, daily for 10 days    adult: 75 mg child 1 year or older and less than 15 kg: 30 mg child 1 year or older and 15 to 23 kg: 45 mg child 1 year or older and 23 to 40 kg: 60 mg child 1 year or older and more than 40 kg: 75 mg OR 1 zanamivir (adult and child 5 years or older) 10 mg by inhalation using the device provided, daily for 10 days.