Seasonal allergies, sinus infections and colds all can cause nasal congestion and make you feel downright miserable, so it can be difficult to tell them apart. Making it even harder, these conditions are linked; nasal blockage caused by allergies or a cold can end up as sinusitis if the blocked mucus becomes infected.

Here's a cheat sheet to help figure out what is causing your misery:

How long it lasts: If your congested nose and breathing difficulty last longer than a week, it's probably not a cold. Most likely, it's allergies, and needs to be treated with an antihistamine, not a decongestant. Sinusitis typically lasts about two weeks, and can follow a bout of allergies or a cold.

Facial pressure and pain: The severity of facial pain and pressure is one of the most telltale factors of a sinus infection. Allergies usually don't cause nearly as much facial pain and pressure as sinusitis does. If you have sinusitis, you can feel pressure and pain in your nose, cheeks, forehead and even upper teeth.

Itching: An itchy, runny nose and watery eyes indicate allergies. This happens as a result of your immune system reacting to a foreign substance (we're looking at you, pollen) by releasing histamines.

Fever, body aches and nausea: If you experience these symptoms, sinusitis is likely to blame. Sinus infections are the result of blocked mucus becoming infected with bacteria, and this infection causes you to feel sicker and more fatigued than you would with allergies or a cold.

Treatments
While the sniffling and congestion may be similar in all three, the treatments should differ. A simple cold can be relieved by an over-the-counter decongestant, while seasonal allergies should be treated with an antihistamine. If symptoms last for more than four days, see a doctor. "It's not good for your body to use decongestants for weeks on end. It's best to make sure what your diagnosis is and get the proper medication," says Dr. Thomas Sellner, Ear Nose and Throat specialist with Carolina ENT.

To treat sinusitis, a prescription antibiotic and topical nasal steroid spray can control the symptoms. For those with chronic sinusitis - meaning it keeps coming back multiple times a year or never really goes away - minimally-invasive sinus surgery may be the best option to control symptoms once and for all.  

Watch Dr. A. J. Goforth, III of Carolina ENT discuss allergy testing, seasonal vs. perennial allergies, and tips for allergy sufferers: 

 Allergy Testing: 

Seasonal vs. Perennial Allergies: