Oseltamivir

Antiviral drugs are prescription medicines (pills, liquid or an inhaled powder) used specifically for treating viral infections. Specific antivirals are used to target specific viruses and, unlike most antibiotics, they inhibit the target pathogen development, instead of destroying it. They are relatively harmless to the host and they should be distinguished from virucides, which are not medication but deactivate or destroy virus particles, either inside or outside the body.
When used for treatment, antiviral drugs can lessen symptoms and shorten the length of the ill period by 1 or 2 days. They also can prevent serious flu complications, like pneumonia. For people with a high risk medical condition, treatment with an antiviral drug can mean the difference between having a milder illness versus a very serious illness that could result in a hospital stay. They may also cause some side effects, including nausea, vomiting, dizziness, runny or stuffy nose, cough, diarrhoea, headache and some behavioural side effects.
The CDC provided some useful guidelines for people and health care professionals regarding antiviral therapies.