Hello.

Thanks for posting your query.

Hot bath causes cutaneous vasodilation that means increase in diameter of veins of skin. This further leads to decrease in blood pressure. This mechanism involves the complicated system of sympathetic and parasympathetic nervous system of body.

This vasodilatation causes pooling of blood to the skin and legs if you are standing. These reduces the blood supply to the brain and the other vital organs like lungs and heart causing shortness of breath.

The palpitations could be caused by a decrease in blood pressure. Decrease in blood pressure makes the heart to work harder and faster to pump the blood to provide sufficient oxygen to the body. This leads to pounding pulse.

This is a physiological mechanism, so do not worry. But, if you are having severe symptoms associated with this, like dizziness, chest pain, lightheadedness, extreme shortness of breath, etc, it is better to get evaluated by physician at the earliest.

Some measures which might help you.
1. Do not use very hot water for bath.
2. Avoid sudden change of posture from sitting to standing.

I hope, this answers your query. Please accept my answer in case you have no follow up queries.

Regards.

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