When blood pressure drops abruptly and is followed by these symptoms, an underlying health issue can be present, adds Mayo Clinic. People who have consistently low readings of their blood pressure and no other problems may not have serious issues, but their doctors may monitor the results of their check-ups closely. A quick and large decrease of blood pressure can result in lightheadedness and fainting. Pregnancy, heart problems, thyroid conditions, severe blood loss, an allergic reaction and severe infection can cause low blood pressure.
The term "iatrogenic" refers to a medical treatment which causes a problem. It's not uncommon for people prescribed high blood pressure medications to end up with blood pressure which is too low. Some people have higher blood pressure when they are in the clinic (something that is called white coat hypertension ) due to anxiety. When this occurs, medications may end up being prescribed which result in blood pressure that is too low outside the clinic. Ambulatory blood pressure monitoring (checking blood pressure outside the stressful setting of the clinic) may be needed to know how aggressive to be in treating high blood pressure to avoid inadvertently causing low blood pressure.