Approved for medical use in 1999, Oseltamivir is an antiviral medication used to treat and prevent influenza A and influenza B (flu). As a matter of fact, many medical organizations recommend it in people who have complications or are at high risk of complications within 48 hours of first symptoms of infection. Basically, this product treats the cause of the flu at its source so that further spreading may be inhibited. When it comes to the side effects of Oseltamivir, they include vomiting, diarrhea, headache, and trouble sleeping. This medication has other side effects that are rather serious such as psychiatric symptoms and seizures. It is worth noting that this drug is recommended for influenza infection during pregnancy, because it has already been taken by a small number of pregnant women without signs of problems. However, dose adjustment may be needed in those with kidney problem. Remember that you may take this medicine with meals or on an empty stomach, even though taking Oseltamivir with food may lessen the possibility of stomach upset.