So we're all looking for ways to fight it. Some doctors are using hands-on techniques to give patients relief, and to help them get better, sooner.
"Turn your shoulders to the left...," says Dr. Lauren Noto-Bell to the young man as she demonstrates Osteopathic Manipulation techniques.
Dr. Noto-Bell, a professor at he Philadelphia College of Osteopathic Medicine, uses her hands, looking for tight spots in the body.
She says those knots can hamper a big element in our immunity - the lymphatic system - a network stretching from head to toe.
"There are a lot of connecting channels and ducts that carry fluid that has cells in them which kill viruses, and bacteria," says Dr. Noto-Bell.
"If the body's lymphatic system is not working properly, then those really important immunologic agents can;t get toe the viruses and red rid of them," she adds.
Dr. Noto-Bell says tight muscles - or even inflammation from an infection like flu - can block the channels.
So she manipulates those areas, to get lymph fluid moving freely again.
And that, she says, will help the body itself fight the flu.
The doctor says studies show that a technique called the Lymphatic pump - jiggling the whole body from the feet - or the chest - stimulates a host of lymph channels.
"I especially like to teach this to parents of children who come in who are sick," she says.
The doctor says the osteopathic manipulations are very easy to learn.
After a treatment, patients often note their bodies feel looser or lighter.
The relief may not always be immediate, but it is noticeable, especially for symptoms like a stuffy head.
"They start to drain, and they're grabbing for the tissues a lot more than they were," she notes.
All osteopathic doctors are trained in the body manipulations, but not all practice them regularly.
So be sure to ask before you schedule a visit to the doctor.