What causes a sudden high fever of 39°C, and what should be done?

Sudden high fever of 39°C may be caused by intense physical exercise, high environmental temperature, acute upper respiratory tract infection, acute gastroenteritis, or acute pyelonephritis. It can be managed through rest, environmental adjustments, and medication. If the high fever persists for more than 24 hours or is accompanied by confusion or difficulty breathing, prompt medical attention is required.

1. Intense physical exercise: After high-intensity exercise, metabolic disturbances in the body lead to increased heat production and inadequate heat dissipation, resulting in stress-induced high fever (39°C), which may be accompanied by fatigue and muscle soreness. It is recommended to immediately stop exercising, move to a cool place to rest, use lukewarm water to wipe areas such as the forehead and armpits for physical cooling, and drink plenty of warm water to stay hydrated.

2. High environmental temperature: Prolonged exposure to hot and humid environments hinders the body's ability to dissipate heat, leading to heat accumulation and heatstroke, manifesting as high fever (39°C), along with dizziness, thirst, and hot skin. It is advised to quickly move to a cooler environment, loosen clothing to facilitate heat loss, take oral rehydration salts to replenish electrolytes, and apply ice packs to the forehead if necessary.

3. Acute upper respiratory tract infection: Viral or bacterial infection of the upper respiratory tract triggers an inflammatory response causing high fever (39°C), accompanied by nasal congestion, sore throat, and cough. Patients may take medications such as acetaminophen tablets, ibuprofen suspension, and ambroxol hydrochloride oral solution under medical guidance to relieve symptoms.

4. Acute gastroenteritis: Consumption of contaminated food leads to bacterial or viral infection of the gastrointestinal tract, causing inflammation and high fever (39°C), along with abdominal pain, diarrhea, and vomiting. It is recommended to take medications such as smectite powder, levofloxacin tablets, and oral rehydration salts (III) under medical supervision to alleviate symptoms.

5. Acute pyelonephritis: Bacteria ascend through the urethra to infect the kidneys, causing inflammation of the renal pelvis and high fever (39°C), accompanied by flank pain, frequent urination, urgency, and painful urination. Follow medical advice to use medications such as cefoperazone sodium and sulbactam sodium for injection, levofloxacin injection, and sodium bicarbonate tablets to improve symptoms.

Daily care should include maintaining indoor ventilation and appropriate temperature and humidity; eating light, easily digestible meals while avoiding spicy and irritating foods; ensuring adequate sleep and avoiding overexertion; regularly monitoring body temperature and observing changes.