It's wintertime, which means plenty of people are coughing, sneezing and blowing their noses. But if you or a loved one start to show these symptoms, how do you know if it's the flu, or just a really bad cold?

It's not easy to tell the difference between a cold and the flu, because the two conditions cause similar symptoms, according to the Centers for Disease Control and Prevention. They are also both viral illnesses, but they are caused by different viruses. The only way to know for sure if you have the flu is to visit your doctor and get a diagnostic test for the flu virus. However, most people with the flu don't need to get a flu test, because the results usually won't change your treatment, the CDC said. [7 Absolutely Horrible Head Infections]

Still, there are some symptoms that tend to be more common with colds than with the flu, and vice versa. In general, flu symptoms tend to be more severe than cold symptoms, according to the CDC. Here are some ways you may be able to tell if you have a cold or the flu:

Symptoms of a cold usually come on gradually, whereas symptoms of the flu can appear suddenly.

Symptoms such as sneezing, a stuffy nose and sore throat are more common with colds than with the flu.

People with the flu usually develop a fever, whereas people with colds rarely do.

The flu often causes body aches and headaches, which can be severe. If you have a cold, aches are usually mild.

The flu can cause serious complications, such as pneumonia or bacterial infections, but such complications are rare with colds.

Regardless of whether you have a cold or the flu, the illness will usually go away on its own, but you should visit your doctor if your symptoms change or get worse, according to the Massachusetts Department of Public Health.

You can also get a seasonal flu vaccine to protect yourself from the flu each year, the CDC said. Unfortunately, there is no vaccine to protect you from the common cold.

Washing your hands frequently can also help prevent either a cold or the flu, since both conditions can spread from person to person via contact with contaminated surfaces. If you get sick with either a cold or the flu, it's important to stay hydrated and get plenty of rest to help your body recover, according to Syracuse University.

Original article on Live Science.