Some authorities would consider low blood pressure to be a problem that requires treating. Doctors in Germany are quite active in raising blood pressure although there is little, if any, evidence to suggest that this is necessary. A low blood pressure should only be treated if symptoms of fainting, dizziness, depression or persisting lethargy are associated with a blood pressure that has a systolic level below 80 or a diastolic level below 50. (Systolic pressure is that of the heart beating and diastolic is the pressure exerted by the arteries, see Hypotension.) So nonplussed appear the authorities that I was unable to find any reference to treatment for non-emergency hypertension in the English language.
Low blood pressure will occur when the heart fails to pump correctly, there is marked blood loss or the blood vessels dilate, usually in response to some toxin, most probably a hypertension drug such as a beta-blocker. Hypotension that occurs suddenly should therefore be considered a medical emergency and be treated accordingly.
A sudden drop in blood pressure must be assessed by a doctor and treated accordingly. Ensure that any blood pressure-lowering drugs are not being taken in excess. Different people have different sensitivities.
Low blood pressure without symptoms should be left alone.
If symptoms are present, try increasing water and protein intake to enhance the volume of blood.