Temperatures over 104 degrees F can cause heat stroke, which can be fatal. King County suggests keeping the temperature between 100 and 104 F.
Soaking too long in hot water can cause overheating. At 104 F, limit your soaking time to between 15 and 20 minutes.
Avoid alcohol while using a hot tub. The combination of the alcohol's depressant effect and the hot water can cause drowsiness and, in extreme cases, loss of consciousness and drowning.
Individuals with body infections, open sores or wounds are encouraged to avoid hot tubs. If a hot tub has not been properly maintained, infections can spread from person to person.
If the hot tub is not properly chlorinated, you may experience a burning sensation in your eyes or a nasty odor. Proper maintenance and disinfectant procedures will minimize these problems.