The human body maintains a stable internal temperature, typically around 37 degrees Celsius (98.6 degrees Fahrenheit), through thermoregulation. This process, primarily managed by the hypothalamus in the brain, balances heat production and loss to sustain optimal organ function and metabolic processes. Slight temperature variations can occur due to factors like time of day, activity level, or menstrual cycles. However, significant deviations often indicate underlying health issues.
Fever: The Body’s Response
A fever, or pyrexia, is an elevated body temperature, considered 37.8 degrees Celsius (100 degrees Fahrenheit) or higher when measured orally. This temperature rise is a deliberate immune response, where the hypothalamus resets to a higher point, creating an environment less hospitable for invading bacteria or viruses. Common symptoms include sweating, chills, muscle aches, headache, and weakness.
While uncomfortable, a mild fever aids the immune system in combating infection. Medical evaluation is warranted for temperatures exceeding 39.4 degrees Celsius (103 degrees Fahrenheit) in adults, or any fever in infants younger than three months old with a rectal temperature of 38 degrees Celsius (100.4 degrees Fahrenheit) or higher. Prolonged fevers lasting more than three days, or those accompanied by severe headache, stiff neck, rash, persistent vomiting, or confusion, also require prompt medical attention. Home care involves resting, staying hydrated, and loosening tight clothing to promote cooling. Over-the-counter medications like acetaminophen can help reduce discomfort, but the focus remains on addressing the underlying cause.
Hypothermia: Dangerously Low Body Temperature
Hypothermia occurs when the body’s core temperature drops below 35 degrees Celsius (95 degrees Fahrenheit). Prolonged exposure to cold environments is the most common cause, but factors like exhaustion, dehydration, or certain medical conditions can increase susceptibility. The body initially attempts to generate heat through shivering and increasing muscle tone.
As hypothermia progresses, symptoms evolve through stages. Mild hypothermia (32-35°C or 90-95°F) presents with shivering, confusion, slurred speech, and clumsiness. In moderate hypothermia (28-32°C or 82-90°F), shivering may cease, and individuals become lethargic with a slow heart rate and breathing. Severe hypothermia (below 28°C or 82°F) leads to unresponsiveness, slow vital signs, loss of reflexes, and organ failure. First aid involves gently moving the person to a warm, dry area, removing wet clothing, and covering them with warm, dry blankets. Applying warm compresses to the neck, chest, and groin helps, and if alert, offering warm, sweet, non-alcoholic drinks helps. Rapid rewarming, such as with hot baths, should be avoided, as it can stress the heart. Hypothermia is a medical emergency; contact emergency services promptly.
Heat-Related Illnesses: Too Hot to Handle
Heat-related illnesses are conditions where the body overheats, distinct from a fever caused by infection. These conditions arise from exposure to high temperatures or strenuous physical activity in hot environments. Heat exhaustion and heatstroke are two distinct manifestations within this category.
Heat exhaustion develops when the body loses excessive water and salt, primarily through heavy sweating. Symptoms include profuse sweating, cold and clammy skin, weakness, dizziness, headache, nausea, and a rapid but weak pulse. Actions involve moving to a cool place, loosening clothing, sipping cool water, and applying cool compresses to the skin. If symptoms do not improve within 30 minutes, or if vomiting persists, seek medical attention.
Heatstroke, conversely, is a life-threatening medical emergency where the body’s internal temperature rises dangerously high, typically above 40 degrees Celsius (104 degrees Fahrenheit). This condition is characterized by hot, red, and often dry skin (though it can sometimes be moist), confusion, slurred speech, seizures, and loss of consciousness. Heatstroke requires immediate emergency medical attention. While waiting for professional help, cool the person rapidly by moving them to a cooler area, removing excess clothing, and applying ice packs to the neck, armpits, and groin, or using a cool water mist.
Medication and Brain-Related Temperature Changes
Beyond external factors and infections, certain medications and neurological conditions can disrupt the body’s thermoregulation, leading to abnormal temperature shifts. Some drugs can induce hyperthermia, an elevated body temperature not caused by fever, by interfering with the body’s heat-dissipating mechanisms. Examples include Serotonin Syndrome, linked to medications that increase serotonin levels, causing symptoms such as agitation, increased reflexes, and high body temperature.
Neuroleptic Malignant Syndrome, another drug-induced condition, arises from certain antipsychotic medications or abrupt withdrawal of dopamine agonists, causing severe muscle rigidity, altered mental status, and hyperthermia. Additionally, brain injuries, such as stroke or trauma, can damage the hypothalamus, the brain’s temperature control center. This damage can result in “central fever,” where the body’s temperature rises without infection, solely due to neurological disruption. Awareness of these internal causes is important, as their management differs significantly from temperature abnormalities caused by environmental exposure or common infections.