What is lower blood pressure number?

Each time that you have your blood pressure measured, it is important that the test is carried out under similar conditions to ensure that the results are consistent. If you have a low blood pressure reading, your GP will first consider the everyday causes that might have affected it, before considering the possible underlying causes.

Many factors have a daily, or sometimes even hourly, effect on your heart and circulation. Below are things that could affect your blood pressure and, in some cases, may cause low blood pressure.

If your blood pressure is still considered low after taking into account everyday factors such as those listed above, there may be another cause. Some possibilities are explained below.

Some medication may cause hypotension as a side effect. This tends to be orthostatic, or postural hypotension (low blood pressure when you stand up or change position). Examples of medication that can cause hypotension include:

Your GP will discuss any possible side effects with you when prescribing medication. While you are taking medication, your blood pressure will be carefully monitored if you are considered to be at risk of hypotension.

If you have an acute (short-term) illness, your blood pressure will be measured regularly because it is a good indicator of the severity of your illness. A heart condition, such as heart failure or a heart attack, can also cause low blood pressure, as your heart may not be able to pump blood around your body.

Autonomic disorders affect your autonomic nervous system and they can cause hypotension. Your autonomic nervous system is part of your nervous system (the network of cells that carry information around your body). It controls the bodily functions that you do not actively think about, such as sweating, digestion and the beating of your heart.

The autonomic nervous system also controls the widening and narrowing of your blood vessels. If there is a problem with it, your blood vessels could remain too wide, causing low blood pressure. In particular, autonomic disorders tend to cause orthostatic hypotension.

Some examples of autonomic disorders are:

The adrenal glands are two small glands that are located just above your kidneys. They produce hormones that control your blood pressure and maintain the balance of salt and water in your body. One of the hormones they produce is called aldosterone, which is responsible for controlling the amount of salt in your body.

If your adrenal glands become damaged - for example through an infection or a tumour - the production of aldosterone may be reduced, resulting in a loss of salt from your body. This can cause dehydration which, in turn, leads to low blood pressure.

If a problem with your adrenal glands is diagnosed, it can be treated by increasing the amount of aldosterone in your body. This could also be a symptom of Addison’s disease (a condition in which the adrenal glands cannot produce enough of the hormones cortisol and aldosterone). Addison’s disease can also be treated with medication.

Low blood pressure can also be caused by serious injuries or burns, particularly if you have lost a lot of blood. This can mean that there is less blood being pumped around your body. Low blood pressure can also occur if you go into shock after having a serious injury.

Other kinds of shock are described below.

Septic shock and toxic shock syndrome are caused by bacterial infections. The bacteria attack the walls of the small blood vessels, causing them to leak fluid from the blood into the surrounding tissues. This causes a significant drop in blood pressure (severe hypotension).

Anaphylactic shock, or anaphylaxis, is caused by an allergic reaction to something - for example, a wasp sting or a peanut. During an allergic reaction, your body produces a large amount of a chemical called histamine, which causes your blood vessels to widen and leads to a sudden, severe drop in blood pressure.

Cardiogenic shock occurs when your heart cannot supply enough blood to your body, so your blood pressure drops. This can happen during a heart attack.

As a general guide, low blood pressure is a reading of 90/60 or less.

Blood pressure is the pressure of blood pushing against the walls of your arteries. Arteries carry blood from your heart to other parts of your body.

Your blood pressure normally rises and falls throughout the day.

Blood pressure is measured using two numbers:

The first number, called systolic blood pressure, measures the pressure in your arteries when your heart beats.

The second number, called diastolic blood pressure, measures the pressure in your arteries when your heart rests between beats.

If the measurement reads 120 systolic and 80 diastolic, you would say, “120 over 80,” or write, “120/80 mmHg.”

A normal blood pressure level is less than 120/80 mmHg.1

No matter your age, you can take steps each day to keep your blood pressure in a healthy range.

High blood pressure, also called hypertension, is blood pressure that is higher than normal. Your blood pressure changes throughout the day based on your activities. Having blood pressure measures consistently above normal may result in a diagnosis of high blood pressure (or hypertension).

The higher your blood pressure levels, the more risk you have for other health problems, such as heart disease, heart attack, and stroke.

Your health care team can diagnose high blood pressure and make treatment decisions by reviewing your systolic and diastolic blood pressure levels and comparing them to levels found in certain guidelines.

The guidelines used to diagnose high blood pressure may differ from health care professional to health care professional:

Most doctors do not consider hypotension a problem unless it is associated with certain signs and symptoms:

According to the AHA, there is no specific number at which day-to-day blood pressure is considered too low. However, when low blood pressure is accompanied by any of the above listed dangerous symptoms, it is time to seek medical care.

Some people have naturally low blood pressure, and they don't experience any symptoms. But for those who are used to having high blood pressure, a sudden decrease in blood pressure can signal a problem and can cause the symptoms listed above.

An episode of hypotension is more likely to occur under these conditions:

Low blood pressure can cause fatigue — that feeling of overwhelming tiredness and lack of energy. Research has found an association between low blood pressure and chronic fatigue syndrome, a condition characterized by profound fatigue, pain, and sleep abnormalities that are often made worse by exertion.

There is no cure for this type of fatigue, but doctors may suggest treating underlying causes, such as sleep disorders or mental health issues. Treating low blood pressure with dietary changes and proper physical activity can also help.

If your blood pressure is always on the low side and you do not have any of the dangerous symptoms, there is usually no cause for concern. Similarly, if you have a single at-home blood pressure reading that is abnormally low without any symptoms, you probably do not need to see your doctor. It is normal for your blood pressure to rise and fall over time, and your body is usually able to get your blood pressure back to normal.

But, says Dr. Lawrence, “when you sense there’s a recurrent problem, or there’s no clear explanation for what’s happened, you need to seek medical advice."

If your blood pressure drops suddenly and you are experiencing symptoms like dizziness, you should call your healthcare provider. They can assess your situation and rule out underlying problems, such as internal bleeding, serious infection, or an allergic reaction.

Treatment for hypotension will depend on the cause of the low blood pressure. Immediate steps might include the following:

After evaluation, a doctor may make these recommendations:

People who experience shock related to hypotension will need emergency treatment to restore blood flow to their organs and raise their blood pressure back to normal.

It’s important to determine whether your low blood pressure is “a primary problem or secondary problem,” notes Lawrence. A primary problem means that the body’s reflexes are not working as they should. Secondary causes mean that the low blood pressure is a result of things like dehydration or the effects of certain medications.

“Some antihypertensive are more likely to cause hypotension than others, and a lot of it is dose-dependent,” says Lawrence. “In most people, there will be some easily identifiable secondary cause or some easy solution to what may even be a chronic problem that has no secondary cause, and that’s why it’s important to see your doctor, so they can make an appropriate assessment.”

Keep track of your blood pressure readings, even if you don’t have any health issues, so that you know what your personal normal reading is. And if your blood pressure is being monitored, talk to your doctor about the blood pressure target range that’s best for you.