Influenza is a virus that causes the flu. Flu symptoms include fever, sneezing, coughing, muscle aches, and exhaustion. Flu is more severe than the common cold, keeps people from their normal activities for up to a week or longer, and can be complicated by bacterial infections, such as pneumonia. Experts recommend flu vaccine to prevent infection in older people and in people with diseases that put them at risk for having a complicated course of flu. Treatment of flu generally involves rest, fluids, and medication to decrease fever and aches. However, antiviral medicines can shorten the course of flu when patients take them within 24 hours of developing symptoms. Available antiviral medicines for treating flu include amantadine, rimantadine, oseltamivir, and zanamivir. Although vaccination is an option for anyone, regardless of age or disease, recommendations do not specifically encourage healthy adults under the age of 60 to get flu vaccine. It is unclear whether the benefits of antiviral medicines for flu are worth the side effects and costs.