The last thing you want in the twilight of the summer is an energy-sapping, cough-ridden cold to push you back indoors, away from the party. The problem is, summer colds too often seem like harmless annual allergies that end up spanning several merciless weeks, if not months. Discerning between the two can be tricky, but knowing what’s going on inside your body can have tremendous benefits for trading time in bed for time in the sun.

First and foremost, a summer cold is not a winter cold. Winter colds typically result from an infection of the rhinovirus; they’re short, nasty, and draining. They come quickly and leave within the week. Summer colds are a different beast. Products of the enterovirus, summer colds tend to leisurely worsen over a stretch of time. Their symptoms are less severe but peskier. A cough or case of the sniffles just won’t seem to go away, making the summer cold seem like a regular case of allergies, but with far greater frustration.

"Winter cold viruses tend to make you feel really sick, and then you get over it," Dr. Bruce Hirsch, infectious disease specialist at North Shore University Hospital, told LiveScience. "Summer colds just seem to lurk in the background…and just go on and on and on."

Experts tend to cite two critical factors that lead to prolonged summer colds. The first is level of physical activity. While routine exercise helps strengthen your immune system, raising the heart rate during a period of illness depletes the body of metabolic resources, making it harder to fight an infection. During the summer, these instances of physical activity naturally rise, as the weather improves and staying inside seems wasteful.

The cold’s severity is compounded when the natural inclination to go outside eventually makes for a return to the air conditioning. Sudden drops in temperature, experts note, can leave a person’s immune system in an even weaker state.

A severe temperature drop "lowers the defenses in the nose and throat by causing constriction of the blood vessels," Professor Ronald Eccles, director of the Common Cold Centre at the University of Cardiff in Wales, told the Wall Street Journal. "If a virus is already present, this reduces our immunity."

It can be a tough pill to swallow: staying inside for the end of the summer and beating your cold seem inferior to spending the remaining days in the sun and letting your sickness and the eventual cold weather push you indoors anyway.

For those who choose to fight the cold head-on, the battle begins by distinguishing it from an allergy. While post-nasal drip, coughing, and a scratchy throat may all indicate both, an allergy is unique in its absence of body aches, diarrhea, and fever. Mucus from a cold will tend to be clear, while allergies produce a more greenish color. Puffy, bloodshot eyes indicate allergies.

"If your nose and eyes and ears feel itchy or tickly, that really points to allergies," Dr. Richard Weber, a professor at the University of Colorado at Denver, told WSJ.

Being able to tell the difference between a cold and allergy not only impacts your current health, but also allows you to choose your future interactions more carefully. Physical activity is detrimental on its own, but with that activity comes congregation, and it’s the gathering of many people that can transmit the virus just as easily, if not more so. Schools, sporting events, and parties can all pose individualized threats to an already depressed immune state.

"Anywhere there's crowding,” Eccles said, “you're likely to pick up a cold.”