"You wake up with a pounding head, your throat is sore and you can't stop coughing. But you have a big meeting at work and an in-box that's piled high. Should you call in sick or head to the office? Are you too sick to go to work?" asks Dr. Vimal George, a family practitioner with The Austin Diagnostic Clinic.

George offers the following advice on how to determine if one should go to work or stay home.

Contagious colds

"How many times have you wished that a coworker who shuffled into the office, coughing into one hand and clutching tissues in the other, had just stayed home?"

While many diseases are contagious before symptoms even appear, colds are most contagious two to four days after the original exposure when the virus is present in nasal fluids, said George.

More than 200 different viruses are known to cause the symptoms of the common cold and they are easily transmitted from person to person.

"If you touch the hand of an infected person or touch a hard surface they've touched -- like a phone -- and then rub your eyes or nose, you can catch a cold," said the physician.

The most common symptoms of a cold include a runny nose, nasal congestion and sneezing. Cold victims also may feel tired, have a sore throat or a headache. "After you've spent a day or two at home and feel well enough to be productive at work, it's safe to head back," said George. "Make sure you don't have a fever, which means you're still contagious, wash your hands frequently and try to avoid close contact with co-workers until symptoms are gone."

Feeling flush?

It can be difficult to tell if you have the common cold or the flu, which can cause severe illness and even death in some people, said George. Highly contagious, the flu can cause cold-like symptoms but also can result in high fever, extreme fatigue and muscle aches.

The general rule is that an adult can infect others with the flu up to five days after they first develop symptoms, the physician said. "Anytime you cough or sneeze near another person, you risk giving them the flu. In addition, some of your coworkers may live with or care for elderly adults or very young children who can be severely affected by the flu."

The best way to avoid getting the flu is by getting a flu shot annually, said George. Many companies offer free or reduced-cost flu shots to their employees, and they're also available at most doctor's offices. Flu season runs from November to April.

"If you haven't gotten your flu shot yet, it's not too late to do so.

"It's important to remember that a healthy adult can infect others one day before symptoms develop," said George. "So even before you know you're sick you can be contagious. That's why flu shots are so important to keeping your work environment healthy."

Double trouble

Whether one has a cold, the flu or another illness, many take medication to help treat the disease or manage symptoms, and that can be double trouble, said the physician.

"In addition to the symptoms you already have, medications can cause side effects such as drowsiness and dizziness and can affect concentration," he said.

"If your job requires a high level of focus to avoid injury or if your inability to function normally can harm someone else, call in sick."

Colds and the flu aren't the only contagious illnesses. For example, fever, throat pain and white patches in the throat could mean strep throat, and bright red eyes with discharge in the corner could be pinkeye -- both diseases are easily spread to others.

"Use common sense when evaluating whether or not you should go to the office," said George.

"If you're feeling ill enough that you think you need treatment, visit your doctor, who can tell you when it's appropriate to go back to work in a way that is safe for you as well as for your co-workers."