“This may be one of the most common questions,” says Dr. Kirk Waibel, former Allergy Consultant to the Army Surgeon General, now at Aspire Allergy & Sinus in San Antonio, Texas.
The key questions to ask that help you determine what you have: Do you have a fever, body aches and/or a sore throat? “These are much more common with a viral illness,” says Dr. Waibel. And if the symptoms pass in seven to 10 days, it’s probably a cold.
“Allergy symptoms can last for weeks during a pollen’s allergy season,” he says. If they go on for longer, and they’re making you miserable, see an allergist—you may need more than one type of allergy treatment to get the best control over allergy symptoms.
Both colds and allergies, however, can leave you with an unpleasant remnant: Yellow or green mucus. “Some viral illnesses and bad allergies can result in a sinus infection that can be chronic and last for months,” he adds. “Patients with chronic sinusitis often complain of upper tooth pain, bad breath, a poor sense of smell, pain or pressure over their face or chronic discolored drainage in the back of their throat.” So your lingering nose-blowing/post-nasal drip issue may be neither a cold nor allergies but something else entirely.