If cold shower is your only option, do it neither with an empty nor a full stomach, suggested by Traditional Chinese Medicine Practitioners.
It is because a cold shower consumes you more energy and may cause you having low blood sugar reaction if your stomach is empty.
And while your stomach is full, the cold water will weaken your gastrointestinal motility and the production of digestive juice, increasing the risk for abdominal pain and diarrhea.
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