Subnormal body temperature

A subnormal or low body temperature is a body temperature below the normal, healthy range. Historically a normal body temperature was considered to be 98.6F (37&deg;C), but more recent research has found the healthy temperature range to be between 97.5 F (36.4 C) and 97.9 F (36.6 C).

Body temperature influences
Body temperature is known to be slightly higher or lower due to many different influences, including:
 * small variations up or down during a typical day
 * age: infants and children under age 10 have a much lower normal temperature range, adolescents have a lower range to adults, people aged 65 or older have a lower healthy temperature range than younger adults
 * sex, and ovulation
 * where the temperature is taken, e.g., ear (which is considered closest to brain temperature), rectal, oral, forehead
 * Differences also exist between different people
 * metabolism and circadian rhythm (body clock)
 * certain chronic medical conditions, (e.g., hypothyroidism: 0.013°C) or higher temperature (e.g., cancer: 0.020°C)

Symptom recognition
The Canadian Consensus Criteria recognizes low body temperature as a neuroendocrine system symptom.

However, a study by Jones et al. (1998) found patients meeting the CDC's 1988 Holmes criteria for chronic fatigue syndrome did not have a lowered core body temperature.

Comparison
Subnormal body temperature is not the same as hypothermia, which is a medically dangerous body temperature of 95F (35°C) or lower and has complications including frostbite and trenchfoot.

Learn more

 * Normal Temperature: What Should Your Body Temp Be? - Cleveland Clinic