38°C to Fahrenheit (38 Degrees Celsius to °F)

Yes, 38°C (100.4°F) is the standard medical definition of a fever. This temperature threshold is used worldwide by healthcare professionals to determine when a body temperature is elevated enough to be considered febrile (feverish).

It's important to note that this threshold applies to oral measurements. For rectal temperatures, the fever threshold is typically 38.3°C (101°F), and for axillary (underarm) measurements, it's 37.5°C (99.5°F) due to measurement variations.

For most healthy adults, 38°C (100.4°F) is not dangerous but indicates the body is fighting an infection. This level of fever can actually help the immune system work more effectively.

However, adults should seek medical attention if:

• The fever exceeds 39.4°C (103°F)
• It persists for more than 3 days
• It's accompanied by severe headache, stiff neck, shortness of breath, chest pain, or confusion
• They have a compromised immune system or chronic medical condition

For babies, 38°C (100.4°F) requires careful attention based on age:

• Newborns (0-3 months): Any fever of 38°C or higher is a medical emergency requiring immediate evaluation
• Infants (3-6 months): Contact your pediatrician for guidance
• Older babies (6+ months): Monitor closely and contact doctor if fever persists or baby seems very uncomfortable

Always use rectal thermometers for most accurate readings in infants, and remember that underarm temperatures can be significantly lower than core body temperature.

Here's a quick mental calculation method for body temperatures around 38°C:

1. Double the Celsius temperature: 38 × 2 = 76
2. Subtract 10%: 76 - 7.6 = 68.4
3. Add 32: 68.4 + 32 = 100.4°F

This gives you the exact conversion of 100.4°F without needing a calculator. For other temperatures near normal body temperature, you can remember that each 1°C change equals a 1.8°F change.

Yes, underarm (axillary) temperatures are typically 0.5°C (0.9°F) lower than oral temperatures. This means if you measure 38°C under the arm, the actual core body temperature is approximately 38.5°C (101.3°F).

This difference is important because:

• The medical fever threshold of 38°C (100.4°F) is based on oral measurements
• An underarm reading of 38°C would correspond to an oral temperature of about 38.5°C
• For accuracy, many doctors recommend adding 0.5°C to underarm readings

Always note which method you used when reporting temperatures to healthcare providers.

While 38°C (100.4°F) itself is not typically dangerous, you should seek medical attention if:

• For infants under 3 months: Any fever of 38°C or higher requires immediate medical care
• For children: Fever lasts more than 48 hours, child is lethargic, not drinking, or has other concerning symptoms
• For adults: Fever exceeds 39.4°C (103°F), persists beyond 3 days, or is accompanied by severe symptoms
• For anyone: Fever is accompanied by stiff neck, severe headache, difficulty breathing, chest pain, or confusion

Remember that the fever itself is often less important than how the person looks and acts. A child with a 38.5°C fever who is playing and drinking may be less concerning than a child with a 38°C fever who is lethargic and refusing fluids.