About Fever (Pyrexia)
What causes Fever
Fever or Pyrexia is defined as an elevation of the body temperature that exceeds the normal daily variation of 36.5°C -37.5 °C or (97.7°F -99.5°F). 98.6° F (37° C) is usually considered a normal body temperature
Types of Fever
Fever is classified based on the duration and height of the temperature
1. Based on Duration of Fever
Classification of fever based on the duration
Types | Duration | Disorders |
---|---|---|
Acute | <7 days | › Malaria › Viral |
Subacute | Up to 2 weeks | Typhoid fever |
Chronic | >2 weeks | Tuberculosis |
2. Based on Height of Temperature
Classification of fever based on temperature height
Temperature | Fahrenheit (°F) |
---|---|
Mild/low-grade fever | 100.5–102.2 |
Moderate grade fever | 102.2–104.0 |
High-grade fever | 104.1–106.0 |
Hyperpyrexia | >106.0 |
Causes of Fever
Any substance that induces fever is called a pyrogen.
The disorders that may cause fever are
- Infectious Diseases (Viral, bacterial, fungal (most common cause))
- Respiratory tract infections
- Gastrointestinal infections
- Urinary tract infections (UTIs)
- Skin infections
- Malaria
- Inflammatory conditions
- Rheumatoid arthritis
- Lupus
- Cancer
- Physiological stress
- Environmental Factor
- Heatstroke
- Drugs
- Cocaine, Amphetamines, etc
What are the symptoms
- Shivering
- Lack of appetite and generalized weakness & malaise
- Sleepiness
- Headache
- Inability to concentrate
Warning Signs of Fever
- Temperature >103oF
- Shortness of breath
- Mental clouding
- Persistent headache
- Fever does not subside in 48 hrs
Diagnostic Evaluation
dentifying the cause of fever by doing lab tests can help treat the patient better.
- CBC (complete blood count )
- Blood cultures/ Widal test
- Chest x-ray
- Urinalysis and urine culture

Treatment at Home
- Take adequate rest
- Wash your skin as soon as possible after sweating
- Consume Plenty of fluids ( fresh fruit juices, glucose, etc) to avoid dehydration
- OTC drugs such as paracetamol/ibuprofen effectively reduce fever
- Talk to a doctor for the best course of treatment