Does sitting in a hot steam room for 10 minutes lower or raise my blood pressure? i heard it lowers bp but wasn't sure why. thank you.

Typically lower: Something that happens in the steam room is the skin blood vessels dilate (open) which decreases the blood pumping in the main circulation thus lowering bp. Also sweating can cause water and salt loss which can also lower bp. If the steamroom "stresses" you however this can increase bp.

Steam room: A hot tub or steam room tends to lower your blood pressure. This is because as your body overheats, it opens up blood vessels to the skin (which is why you turn red), and this in turn reduces the pressure in the central arteries that are used for blood pressure measurement.