[8] It can occur in individuals with allergies, exposure to environmental irritants, structural abnormalities of the nasal cavity and sinuses and poor immune function.

[10] The diagnosis of sinusitis is based on the symptoms and their duration along with signs of disease identified by endoscopic and/or radiologic criteria.

[13] Prevention of sinusitis focuses on regular hand washing, staying up-to date on vaccinations, and avoiding smoking.

[19] Acute sinusitis can present as facial pain and tenderness that may worsen on standing up or bending over, headache, cough, bad breath, nasal congestion, ear pain, ear pressure or nasal discharge that is usually green in color, and may contain pus or blood.

A way to distinguish between toothache and sinusitis is that sinusitis-related pain is usually worsened by tilting the head forward or performing the Valsalva maneuver.

[22] Symptoms include facial pain, headache, night-time coughing, an increase in previously minor or controlled asthma symptoms, general malaise, thick green or yellow nasal discharge, feeling of facial fullness or tightness that may worsen when bending over, dizziness, aching teeth, and bad breath.

[24] 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.

[31] It is thought to result from restricted venous drainage from the sinuses and affects the soft tissue of the eyelids and other superficial structures.

[31] Stage III, known as subperiosteal abscess, occurs when pus collects between walls of the orbit and the surrounding periosteal structures.

In rare cases, mild personality changes, headache, altered consciousness, visual problems, seizures, coma, and even death may occur.

[34] Specifically, the combination of frontal sinusitis, osteomyelitis and subperiosteal abscess formation is referred to as Pott's puffy tumor.

If the infection is of bacterial origin, the most common three causative agents are Streptococcus pneumoniae (38%), Haemophilus influenzae (36%), and Moraxella catarrhalis (16%).

These infections are typically seen in people with diabetes or other immune deficiencies (such as AIDS or transplant on immunosuppressive antirejection medications) and can be life-threatening.

[28] The medical management of chronic rhinosinusitis is now focused upon controlling the inflammation that predisposes people to obstruction, reducing the incidence of infections.

[48] Exposure to fine particulate matter (PM2.5), which consists of particles less than 2.5 micrometers in diameter, has been associated with an increased risk of developing rhinosinusitis.

[49][50] PM2.5 particles can penetrate deep into the respiratory tract, reaching the nasal and sinus mucosa, leading to inflammation and impaired mucociliary clearance.

[51] Individuals living in areas with higher concentrations of PM2.5 experience increased symptoms and exacerbations of chronic rhinosinusitis.

[54] These smaller particles bypass the nasal hair filtering mechanism and deposit in the mucous membranes of the sinuses, leading to greater inflammatory responses.

[61] Both forms of chronic rhinosinusitis are considered to be highly heterogenous, each with the ability to demonstrate three inflammatory endotypes, the third being a Th17 response.

[76] There is no clear evidence that plant extracts such as Cyclamen europaeum are effective as an intranasal wash to treat acute sinusitis.

[82] Because of increasing resistance to amoxicillin the 2012 guideline of the Infectious Diseases Society of America recommends amoxicillin-clavulanate as the initial treatment of choice for bacterial sinusitis.

[85] The IDSA guideline suggest five to seven days of antibiotics is long enough to treat a bacterial infection without encouraging resistance.

[86] For cases confirmed by radiology or nasal endoscopy, treatment with intranasal corticosteroids alone or in combination with antibiotics is supported.

[89][90] There is only limited evidence to support short treatment with corticosteroids by mouth for chronic rhinosinusitis with nasal polyps.

[91][92][93] There is limited evidence to support corticosteroids by mouth in combination with antibiotics for acute sinusitis; it has only short-term effect improving the symptoms.

[59] For chronic or recurring sinusitis, referral to an otolaryngologist may be indicated, and treatment options may include nasal surgery.

[100] However, if a traditional FESS with Messerklinger technique is followed the success rate will be as low as 30%, 70% of the patients tend to have recurrence within 3 years.

On the other hand with use of TFSE technique along with navigation system, debriders and balloon sinuplasty or EBS can give a success rate of over 99.9%.

[42] Histopathology of sinonasal contents removed from surgery can be diagnostically valuable: A study has shown that patients given spray formulation of 0.73 mg of Tremacamra (a soluble intercellular adhesion molecule 1 [ICAM-1] receptor) reduced the severity of illness.

[48] Based on recent theories on the role that fungi may play in the development of chronic sinusitis, antifungal treatments have been used, on a trial basis.