Acute sinusitis usually follows a viral infection in the upper respiratory tract , but allergy-causing substances (allergens) or pollutants may also trigger acute sinusitis. A Viral infection damages the cells of the sinus lining, leading to inflammation. The lining thickens, obstructing the nasal passage. This passage connects to the sinuses. The obstruction disrupts the process that removes bacteria normally present in the nasal passages, and the bacteria begin to multiply and invade the lining of the sinus. This causes the symptoms of sinus infection. Allergens and pollutants produce a similar effect.
The potential causes of fatigue are numerous. The majority of diseases known to man often list fatigue or malaise as possible associated symptoms. This is complicated by the fact that fatigue can occur in normal healthy individuals as a normal response to physical and mental exertion. However, normal fatigue may begin to become abnormal if it becomes chronic, extreme or prolonged fatigue; usually this occurs when a person experiences chronic or prolonged physical or mental exertion. For example, unusually hard physical or mental exertion for one day can result in normal fatigue that may last about a day or sometimes more, depending on the exertion level, while daily unusually hard physical or mental exertion may result in prolonged fatigue (usually greater than 24 to 48 hours). This latter situation may develop into abnormal fatigue.