Treatment of sinusitis in the United States results in more than US$11 billion in costs. The unnecessary and ineffective treatment of viral sinusitis with antibiotics is common. Signs and symptoms
Headache, facial pain, or pressure of a dull, constant, or aching sort over the affected sinuses is common with both acute and chronic stages of sinusitis. This pain is usually localized to the involved sinus and may worsen when the affected person bends over or lies down. Pain often starts on one side of the head and progresses to both sides. Acute sinusitis may be accompanied by a thick nasal discharge that is usually green in color, and may contain pus or blood. Often, a localized headache or toothache is present, and these symptoms distinguish a sinus-related headache from other types of headaches, such as tension and migraine headaches. Another way to distinguish between toothache and sinusitis is that the pain in sinusitis is usually worsened by tilting the head forward and with the Valsalva maneuver.Other symptoms associated with acute rhinosinusitis include cough, fatigue, hyposmia, anosmia and ear fullness or pressure.Sinus infections can also cause middle-ear problems due to the congestion of the nasal passages. This can be demonstrated by dizziness, "a pressurized or heavy head", or vibrating sensations in the head. Postnasal drip is also a symptom of chronic rhinosinusitis.Halitosis (bad breath) is often stated to be a symptom of chronic rhinosinusitis; however, gold-standard breath analysis techniques have not been applied.
Theoretically,  several possible mechanisms of both objective and subjective halitosis may be involved.A 2005 review suggested that most "sinus headaches" are migraines. The confusion occurs in part because migraine involves activation of the trigeminal nerves, which innervate both the sinus region and the meninges surrounding the brain. As a result, accurately determining the site from which the pain originates is difficult. People with migraines do not typically have the thick nasal discharge that is a common symptom of a sinus infection.Symptoms of chronic sinusitis may include nasal congestion, facial pain, headache, night-time coughing, an increase in previously minor or controlled asthma symptoms, general malaise, thick green or yellow discharge, feeling of facial fullness or tightness that may worsen when bending over, dizziness, aching teeth, and bad breath. Often, chronic sinusitis can lead to anosmia, the loss of the sense of smell. By location
The four paired paranasal sinuses are the frontal, ethmoidal, maxillary, and sphenoidal sinuses. The ethmoidal sinuses are further subdivided into anterior and posterior ethmoid sinuses, the division of which is defined as the basal lamella of the middle nasal concha.