To know if you have a fever, the most accurate method is to measure your body temperature with a thermometer. A fever is generally defined as a body temperature above 100°F (37.8°C) or 38°C, depending on the source and method of measurement (oral, ear, rectal, forehead)
How to tell if you have a fever
- Use a thermometer:
- Oral temperature ≥ 100°F (37.8°C) usually indicates a fever.
- Fever is often defined as a temperature above 38°C (100.4°F) for sustained periods
* Thermometers can be oral, ear, rectal, or forehead types, with rectal measurements often considered most accurate for infants
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Observe common symptoms:
Even without a thermometer, you might suspect a fever if you experience:- Feeling unusually hot or warm to the touch, especially on the forehead or chest
- Sweating or chills and shivering
- Headache
- Muscle aches
- Loss of appetite
- General weakness or fatigue
- Irritability (especially in children)
- Dehydration signs (dry mouth, dark urine)
- Additional signs in children:
- Greater irritability or fussiness
- Lethargy or unusual sleepiness
- Flushed or pale skin
- Refusal to eat or drink
- Difficulty swallowing
- Other indicators:
- Feeling hot but sometimes also feeling cold or shivery despite a high temperature
- Fast breathing or thirst may accompany fever
When to seek medical advice
- Fever lasting more than 3 days or worsening
- Very high fever (≥ 39.4°C or 103°F)
- Accompanying severe symptoms like confusion, stiff neck, persistent vomiting, rash, difficulty breathing, or seizures
- Infants under 3 months with a fever over 38°C
Summary
- Check your temperature with a thermometer to confirm a fever (≥ 38°C or 100.4°F).
- Look for symptoms like hot skin, chills, sweating, headache, muscle aches, and weakness.
- In children, watch for irritability, lethargy, and refusal to eat or drink.
- Seek medical help if the fever is very high, persistent, or accompanied by serious symptoms.
This approach ensures accurate detection and appropriate response to a fever
