Most people don't see winter as allergy season. But millions suffer with a runny nose or puffy eyes, symptoms that can be very similar to the cold and flu, which are both very common this time of year. As cold season ramps up knowing the difference between allergies and colds is important, especially, with a new study showing allergies could be affecting your brain.

The Georgetown University School of Medicine study looked at 98 patients suffering from allergies. Of those participants, an overwhelming 82 percent say they experienced extreme fatigue. The good news is treatment can help...but how do you know if what you have is allergies, a cold or even the flu?

"I have congestion, runny nose, my fatigue is at high levels. I have trouble focusing and sometimes even a little blurry vision,” says Aaron Shiffrin who suffers from winter allergies.

"A lot of the symptoms are similar but there's key ways to distinguish between them. The fever is the number one thing. The difference is a cold usually should start off with a fever over 100.4 and that's usually the big distinguishing thing," says Dr. Matthew Olson, a family medicine doctor at Marshfield Clinic in Lake Hallie.

He goes on to explain that a cold's duration usually peaks in 3 days then you should be getting better besides a lingering cough.

"If you got this constant runny nose that's not getting better despite getting some rest and taking fluids then that's probably a sign you're talking about allergies." Dr. Olson says simply using over the counter allergy antihistamines can provide relief.

"There's very little downside in trying that for a couple days to see if that helps your symptoms, and if that doesn't work come see your doctor."

Shiffrin takes allergy shots relieving him from symptoms that can be debilitating and he's breathing easier. "The energy levels have improved. I no longer feel like I’m sick. I don't worry about it anymore."

The study showed evidence that when allergens that enter the body, chemicals like histamines actually slow down brain function making people irritable, depressed, and even show symptoms of attention deficit disorder.