What exactly is 'blood pressure'?
So what's normal? And what's high?
Can blood pressure be too low?
A sudden drop in blood pressure can occur when standing or sitting up suddenly (often in the morning, or when getting out of a bath, for example), but in healthy people, will regulate relatively quickly as the body adjusts. However, a sudden and severe drop in blood pressure that doesn't stabilise can be life-threatening, as the body can go into shock, which is a potentially fatal state.