coldYou wake up in the morning feeling like crud: Your throat hurts, your nose is runny, your muscles ache, and all you want to do is crawl back into bed, pull your covers over your head, and sink into a deep, deep sleep.

But how do you know if what you've got is a cold or the flu? Both are respiratory illnesses and share many symptoms, making them very difficult to tell apart, but the flu can sometimes lead to more serious complications, like pneumonia or bacterial infections, which can be dangerous.

Colds are usually milder than the flu. They come on slowly and may last less than a week -- though a really bad cold might settle in for longer. Early symptoms generally include a scratchy, sore throat and then a drippy nose, maybe some sneezing, eventually leading to a mild cough. Adults with colds usually don't run a fever, though young kids sometimes do.

The flu, on the other hand, often announces itself with a miserable headache and a dry cough. (A drippy nose and sore throat do sometimes occur with the flu, but less frequently than they do with a cold.) You'll feel achey and exhausted and may see the mercury rise as high as 104 degrees Fahrenheit on your thermometer. You may feel better in a couple of days, or you may drag around feeling wiped out for weeks. On the bright side, while most people get a few colds a year, it's unusual to get the flu more than once annually.

A quick rundown of symptoms:

Fever
Colds: Rare in adults
Flu: May range between 100 degrees and 104 degrees Fahrenheit and last several days

Body aches
Colds: Occasional, but mild
Flu: Frequent, persistent, and sometimes intense

Tiredness/weakness/exhaustion
Colds: Occasional, but mild
Flu: May be intense, last for weeks

Sore/scratchy throat
Colds: Frequent
Flu: Occasional

Stuffy/drippy nose/sneezing
Colds: Frequent
Flu: Occasional

Cough
Colds: Occasional, mild, hacking
Flu: Frequent, dry, sometimes intense

Headache
Colds: Rare in adults
Flu: May come on suddenly; may be intense

 

Image via m.gifford/Flickr