Causes

There are a number of possible causes of this condition, including:

• Heart conditions, such as abnormal heartbeats called arryhythmias or congestive heart failure. Cardiac tamponade, a condition in which fluid builds up around the heart and prevents it from pumping well, is another possible cause.
• Nervous system conditions. One example is diabetic neuropathy, or nerve damage caused by high glucose levels when diabetes is not well controlled. Serious head injuries or other nervous system damage may also cause low blood pressure.
• Dehydration, which may be due to vomiting, diarrhoea or not getting enough fluids.
• Excessive blood loss
• A very serious blood infection known as sepsis.
• Hypothermia, or an abnormally low body temperature.
• Severe allergic reactions of any kind, often called anaphylaxis.
• Low levels of oxygen in the blood, called hypoxia , which may be due to severe asthma, pneumonia, or other conditions.
• A hormone imbalance known as adrenal insufficiency, which can be caused by Addison's disease Addison's disease occurs when the adrenal glands in the body are destroyed and no longer able to produce certain hormones needed for life.
• High levels of acid in the blood, such as respiratory acidosis or metabolic acidosis.
• Medications, such as those used to treat high blood pressure. In this case, the medication may work too well and make the blood pressure too low. Many other medications, such as the sedative diazepam or amitriptyline, which is used to treat depression, can cause low blood pressure in some people.

Other causes are also possible. In some cases, no cause can be found. Some people always have a blood pressure that is low compared to other people, but normal for them. They may not have any symptoms from their low blood pressure because it is normal for them.

Prevention

Prevention is related to the cause. Avoiding dehydration can put a stop to cases due to this cause. Avoiding medications known to cause low blood pressure can prevent cases due to this cause. A person who takes medication to treat high blood pressure is instructed to not double up on medication if he or she misses a dose. This can lead to low blood pressure.