Normal body temperature depends on when, where, and in whom it is measured and this normal varies from person to person. The normal range for body temperature is 97 to 100 degrees Fahrenheit or 36.1 to 37.8 degrees Celsius (actually 98.2 plus or minus 0.6 i.e. 97.6° to 98.8° F). This normal range varies due to an individual’s metabolic rate, being directly proportional to it. The body temperature will also vary throughout the day, usually being lowest in the early morning and rising as much as 1°F (0.6°C) in the early evening. Other factors that might affect the body temperature of an individual may be the part of the body in which the temperature is measured at. Oral temperature, which is the most convenient type of temperature measurement, is at 37.0 °C. This is the accepted standard temperature for the normal core body temperature. Axillary (armpit) temperature is an external measurement taken in the armpit or between two folds of skin on the body and is about 97.6 °F or 36.4 °C. Rectal temperature is an internal measurement taken in the rectum, which falls at 99.6 °F or 37.6 °C. In addition, sex, and racial differences also affect body temperature.
I do not think that a core temperature of that level would affect an individual’s metabolism if the body thermostat were set to that level. As the control of temperature is regulated by hormones, cytokines and other biologically active substances, their synthesis and secretion would be adjusted to this ‘normal’ body temperature. The use of drugs would affect the normal physiology as they would interfere with the normal regulatory mechanisms.
The duration and magnitude of heat that cells can tolerate is called the thermal maximum and beyond this the cellular proteins begin to denature. A core temperature of 107.6°F (42°C) is the thermal maximum for humans. The body resists heat damage by producing heat-shock proteins and states where the level of these proteins is low e.g. genetic causes, old age, poor acclimatisation etc. increase the risk for heat injury.