Fever

Almost any infection can cause a fever. Some common infections are

• Respiratory infections such as colds or flu -like illnesses, sore throats, ear infections, sinus infections, infectious mononucleosis , and bronchitis
• Urinary tract infections
• Viral gastroenteritis and bacterial gastroenteritis
• More serious infections such as pneumonia, bone infections (osteomyelitis), appendicitis, tuberculosis, skin infections or cellulitis, and meningitis

Children may have a low-grade fever for one or two days after some immunizations.

Teething may cause a slight increase in a child's temperature, but not higher than 100 °F.

Autoimmune or inflammatory disorders may also cause fevers. Some examples are:

• Arthritis or connective tissue illnesses such as rheumatoid arthritis, systemic lupus erythematosus
• Ulcerative colitis and Crohn's disease
• Vasculitis or periarteritis nodosa

The first symptom of a cancer may be a fever. This is especially true of Hodgkin's disease, non-Hodgkin's lymphoma, and leukemia.

Other possible causes of fever include

• Blood clots or thrombophlebitis
• Medications, such as some antibiotics, antihistamines, some seizure medicines