Fever is defined as an increase in body temperature above 99°F (37.2°C). The cause of fever may be some infections, diseases of the nervous system, and certain neoplasms. Fever is not considered a disease, it is taken as a sign because it appears in case of infection. It is a protective function of the body. Increasing temperature body tries to destroy the bacteria through phagocytosis.

Sign and Symptoms of fever

There are many signs and symptoms of fever are there. These symptoms also vary with the nature of the disease. Systematic wise symptoms are as follows:

System	Symptoms
Respiratory systems	Shallow and rapid breathing
Cardiovascular system	Increased pulse rate, sometimes palpitation occurs.
Alimentary system	Dry mouth, coated tongue, anorexia, nausea, vomiting, constipation, diarrhea.
Urinary system	Decreased urinary output, burning micturition, yellow-colored urine.
Nervous system	Headache, restlessness, irritability, insomnia, convulsions, delirium.
Musculoskeletal system	Malaise, fatigue, body pain and joint pain.
Integumentary system	Heavy sweating, hot flushes, goose flesh, shivering, or rigors.

Types of fever

Fastigium fever is the period when body temperature reached its maximum and remains constant at that level. Defervescence or decline fever: In this condition, the temperature of the body returns to normal. Returning process of the temperature may be gradual(Lysis) or sudden (crisis). Crisis: It is a condition in which there is a sudden decrease of the temperature to normal from high temperature. True crisis: Temperature decreases to normal within a few hours and patients’ condition also improved. False crisis: False crisis is a sudden fall of temperature and improvement in a patient’s condition. But the fever returns back after some time. Lysis: Temperature decreases in a zigzag manner and it takes 2 to 3 days to become normal. Constant/Continuous fever: Constant fever is a high temperature is maintained in the body. It only varies between 2 to 3 degrees in the morning and evening. Remittent fever: Variation in body temperature occurs more than 2 to 3 degrees in the morning and evening. Intermittent or quotidian fever: Temperature rises from normal to subnormal to high temperature and then returns back to normal. Again the same cycle is repeated. Inverse fever: In this type of fever the highest temperature is recorded in the morning and the lowest temperature in the evening. Hectic or swinging fever: When the difference between high temperature and low temperature is big it is called hectic or swinging fever. Relapsing fever: It is one in which there are brief febrile periods followed by one or more days of normal temperature. Irregular fever: If fever can not be classified under any criteria, it is called irregular fever. Rigor: Rigor is a sudden severe attack of shivering in which the body temperature increases rapidly. Low pyrexia: Body temperature does not rise above 99 to 100°F or between 37.2°C to 37.8°C. Moderate pyrexia: Body temperature remains between 100°F to 103°F or 37.8°C to 39.4°C. High pyrexia: Body temperature remains between 103°F to 105°F or 39.4°C to 40.6°C. Hyperpyrexia: Temperature above 105°F. Hyperthermia: Body temperature above 105°F. Hypothermia: Body temperature below 95°F or 35°C.