Sinus infections, or sinusitis, sometimes cause an unpleasant odor in the nose or a bad-smelling discharge, says WebMD. Sinusitis results from infection, either viral, bacterial or fungal, reports Mayo Clinic.
Sinus infections occur when there is blockage or inflammation of the nasal passages, says the Mayo Clinic. The most common cause is a cold, but allergies and upper respiratory tract infections also cause sinusitis. Nasal blockage is a common symptom, according to WebMD, as are pain and pressure, fever, cough, headache and discharge. This discharge sometimes causes an odor in the sufferer's nose that even others who are near to the sufferer detect with their own noses. Since these symptoms also accompany the common cold, timing is important. There is reason to suspect a sinus infection is present if symptoms persist longer than 10 days.
Sinusitis frequently clears on its own without treatment, or with medication to ease discomfort, says WebMD. Sinusitis that lingers or recurs may be a chronic infection in need of medical attention, reports Mayo Clinic. While feelings of pressure are common with any sinus infection, actual swelling is cause to consult a doctor, as is a severe fever, confusion, vision problems, a stiff neck or difficulty breathing.