With ragweed season approaching, it’s important to be able to tell which is which so you can know what course of treatment to take, says Allen Seiden, MD, a professor of otolaryngology at the University of Cincinnati (UC) and director of University Sinus and Allergy at University Pointe in West Chester.

“Probably the most significant allergen in North America is ragweed,” Seiden says, adding that ragweed season starts in mid-August and lasts until the first frost. “And people who are sensitive will start having itchy or watery eyes, itchy nose, sneezing—that sort of thing.”

With a cold, the throat is more sore than itchy, and there is more general muscle ache and discomfort than with allergies. An infection in the sinus cavity can make the head feel full and congested, leading to a pressure headache.

Allergies tend to cause clear, runny, thin mucus, Seiden says, while colds and sinus infections both can have discolored mucus. “People often come in with a cold thinking they must have a bacterial infection,” he says, “but that may not be the case.”

Seiden says a cold generally lasts five to 10 days, but is usually starting to get better after five days. “So the rule of thumb is if after five days you start to get worse, or if you’re still symptomatic after 10 days, then you probably don’t have a cold—you probably have a bacterial infection.”

Such an infection would be treated with antibiotics, Seiden says. With allergies, the treatment generally involves antihistamines, which fight the histamines that are released during an allergic reaction.

There are several antihistamines that are available over the counter and do not cause drowsiness, Seiden says. In addition, there are nasal sprays that are available by prescription that are also effective for allergies.

And, of course, you can avoid exposure by keeping yourself in an air-conditioned environment when pollen counts are high. “So typically, if it’s a dry, windy day it’s not a good time to be outside if you’re allergic to ragweed,” he says.

Seiden also notes that allergies can lead to sinus infections as a result of a stuffy nose that blocks sinuses.

“So it’s important to keep your allergies under control” he says, “and it’s important to try to treat a bacterial infection if you get one in your sinuses. But with colds, the treatment remains simply supportive therapy.”

In other words, there’s still no cure for the common cold.