Winter is a time of year when cold and flu become much more prevalent. The colder weather means spending more time indoors and in tight quarters with others, which can lead to the spread of these illnesses from one person to another. Getting sick with either illness is never fun, and it can be difficult to know exactly what it is that you’re sick with. That’s why we’ve put together this list of the key differences between the two so you can more easily tell the difference between cold and flu.

1. Type of Virus

The biggest difference between cold and flu lies in the type of virus that causes the illness. Both cold and flu are respiratory infections caused by viruses, but the viruses that cause them are different. The flu is caused by influenza viruses, the most common of which are strains of influenza A virus. The common cold can be caused by more than 200 different viruses. Rhinoviruses cause the majority of colds, but colds can also be caused by coronaviruses, respiratory syncytial virus (RSV), and a variety of lesser-known viruses.

2. Types of Symptoms

When you get sick, the easiest way to tell the difference between cold and flu is looking at the symptoms you’re experiencing. Both the common cold and the flu cause symptoms of a respiratory infection, which can include sore throat, cough, runny nose, and sneezing. However, there are some symptoms that are more oftenly associated with one versus the other, and the presence of these symptoms can help you figure out which one you have.

If you have a fever, you most likely have the flu, as colds rarely cause fevers. The flu also tends to cause muscle aches, headaches, fatigue, and chills, whereas you won’t typically have these symptoms with a cold. While both colds and the flu can cause sneezing, sore throat, and stuffy nose, these symptoms are more commonly associated with colds. You can also look at the nature of your cough to tell the difference between cold and flu. A wet, productive cough is common with a cold, while a dry cough and chest tightness are often associated with the flu. Overall, flu symptoms tend to feel much more severe than cold symptoms.

3. Onset of Symptoms

Not only can looking at the symptoms themselves help you tell the difference between cold and flu, but examining how quickly those symptoms develop can also be a key differentiator. When you get sick with a cold, your symptoms will typically develop gradually over the course of a couple days. The flu, on the other hand, comes on much more suddenly and without warning.

4. Duration

The duration of your symptoms may be able to help you determine whether you have a cold or the flu. However, this is not the best indicator as you won’t know its duration until the end. Cold symptoms have an average duration of three to ten days. Some symptoms such as a cough can persist for longer. If you have the flu, your symptoms may last one to two weeks. Feelings of fatigue and cough may last longer even after your body has recovered.

How to Avoid Getting Sick with Cold and Flu

Now you know more about the difference between cold and flu. While it’s important to know how to tell the difference between these two respiratory illnesses, it’s best to try to avoid getting sick in the first place. If you want to keep your body healthy, check out these top 5 ways to boost your immune system so your body can protect itself against viruses and keep you from feeling sick.