Sinusitis can often be painful with many symptoms that cause a lot of discomfort. There are many causes of sinusitis, yet only two types, acute sinusitis and chronic sinusitis. Acute sinusitis is when the symptoms come very rarely due to an infection or inflammation. Chronic sinusitis is when the symptoms keep occurring frequently. This is more because of the constant presence of allergens or a permanent anatomical defect that must be rectified.

Sinusitis is often characterized by running nose, blockage, congestion and difficulty in breathing and stuffiness. The mucus in the nose that is secreted in excessive quantities in case of a running nose should also be observed to indicate what the cause is. It could be green or slightly yellow, thick or thin, or in some cases blood streaked due to a ruptured blood vessel affected by excessive blowing of the nose.

The most prominent cause of sinusitis is infection and inflammation due to micro-organisms. Sinusitis is often caused by virus. There are thousands of virus strains and hence it is difficult to control such a viral attack. The symptoms are all similar to common flu and it is usually referred to as a upper respiratory infection. The worrying part is that even if it is common, it should be treated otherwise it may lead to the more serious bacterial infection. Sinusitis caused by viral infection might last for 2 weeks during which one might suffer from a lot of mucus. This could be treated by using antibiotics targeted at the virus. Antibiotics in themselves are very powerful drugs and one should not stop the course midway else the condition will revert back to the original symptoms.

Fungal infection is the third variety of infection leading to sinusitis. Although harmless, fungi present in the respiratory tract tend to have adverse affects once the body loses its strength of immunity. They usually feed on dead organisms, but in this case, they start affecting the live cells of the mucus lining causing it to swell. The warm, humid environment in the nasal tracts helps fungus to grow and multiply. Fungi that cause sinusitis include molds, yeast, puffballs and mushrooms. The two kinds of infection caused by fungi are invasive and non-invasive fungal infections. The invasive fungal sinusitis could further be either chronic indolent sinusitis or fulminant sinusitis. The latter is dangerous as the fungi attacks the body as a result of lowered immunity system and can even infect cavities of the bone that protect important organs like eyeballs and brains. Chronic indolent sinusitis on the other hand causes headaches and swelling face. The invasive fungal infection is often characterized by facial pain only on one side, and obstruction in the nasal passages.

Noninvasive fungal sinusitis could be either mycetoma or allergic fungal sinusitis. In the former case spores are formed in sphenoid and maxillary sinus cavities whereas the latter is more due to the body affected by fungi present in the air. Thus fungi can be harmful and sinusitis treatment should be immediate to ensure it doesn't spread to all the cavities and other organs.

Bacterial infection is another main cause of sinusitis. Bacteria like Streptococcus Pneumoniae and Haemophilus influenza, which are responsible for other respiratory problems like pneumonia and flu cause sinusitis. These bacteria found in the respiratory tract of people attack when the immunity system of a person isn't functioning at par. Another example of bacteria that causes sinusitis is Staphylococcus. Bacterial infection is usually caused by drinking contaminated water.