What is low blood pressure (hypotension)?

Your blood pushes against your arteries with every heartbeat. The force of blood pushing against your artery walls is called blood pressure. Blood pressure goes up and down in response to your regular activities, such as sleeping and moving around. The medical term for low blood pressure is hypotension. Blood pressure is made up of two measurements: when your heart beats, and in the periods of rest between heartbeats.

• Systolic pressure (or systole) is the measurement of your blood pumping through your arteries when the ventricles of the heart squeeze. Systole supplies your body with blood.
• Diastolic pressure (or diastole) is the measurement for the periods of rest. Diastole supplies your heart with blood by filling the coronary arteries.

Your blood pressure reading is made up of two numbers: first the systolic measure, then the diastolic measure. Having a lower blood pressure is good in most cases (less than 120/80). But low blood pressure can sometimes make you feel tired or dizzy. In those cases, hypotension can be a sign of an underlying condition that should be treated. Hypotension in adults is defined as a blood pressure reading of lower than 90/60.

Types of hypotension

There are several types of hypotension. Low blood pressure is categorized according to when it happens and what’s causing it.

Orthostatic

Orthostatic hypotension (also known as postural hypotension) is the drop in blood pressure that occurs when you move from sitting or lying down to standing. As your body adjusts to the position change, you may feel dizzy or lightheaded. This is what some people refer to as “seeing stars” when they get up. Orthostatic hypotension is the most common form of low blood pressure. It can affect people of all ages, but it’s especially common in older adults. Aging and pregnancy can also cause an overall lowering of blood pressure. Conditions affecting the autonomic nervous system, such as Parkinson’s disease and diabetes, can often lead to orthostatic hypotension. This form of low blood pressure affects 30 to 50 percent of people with Parkinson’s disease, and about 30 percent of people with diabetes.

Postprandial

Postprandial hypotension is a drop in blood pressure that occurs after eating. According to a 2010 review, low blood pressure after eating is more common in older adults and people with autonomic dysfunction.

Neurally mediated

Blood pressure is a balancing act between your nervous system and other bodily systems (like your hormones and organs). Neurally mediated hypotension happens when there is an abnormal reflex interaction between the heart and the brain. Causes of neurally mediated hypotension include:

• Standing in one position for a long time. Children experience this form of hypotension more often than adults.
• Having a strong emotional response, such as feeling shocked or scared. Some people experience low blood pressure during medical or dental procedures for this reason.

Severe

A severe drop in blood pressure can occur during shock. Shock can happen if you experience a serious injury or infection. During shock, your organs do not get the blood and oxygen they need to function properly. Severe hypotension can be life threatening if not treated quickly.

Other types

Having low blood pressure all the time can be a side effect of some medications. For example, medications used to treat high blood pressure can sometimes cause hypotension. Other conditions affecting the heart, nerves, liver, or hormone systems can also cause an overall lowering of blood pressure. Vitamin deficiencies can also contribute to lower blood pressure.

What causes hypotension?

Everyone’s blood pressure drops at one time or another. Your body’s internal regulation of blood flow can sometimes cause you to have lower-than-normal blood pressure. Some people have low blood pressure all the time, without symptoms. The cause of this type of hypotension is unknown.

What causes a sudden drop in blood pressure?

A sudden decrease in blood pressure can happen after certain events. These include:

• standing up quickly
• eating a meal
• feeling suddenly afraid or experiencing a shocking event

Conditions that can cause low blood pressure

Certain conditions can cause long periods of hypotension that can become dangerous if left untreated. These conditions include:

• pregnancy, due to an increase in demand for blood from both the pregnant person and the growing fetus
• impaired circulation caused by a heart attack or heart condition
• dehydration, for example if you’re vomiting and can’t keep liquids down, or have severe diarrhea
• endocrine disorders, such as diabetes, adrenal insufficiency, and thyroid disease
• autonomic dysfunction, damage to the nerves that control some bodily functions
• prolonged bed rest
• shock, a serious condition in which your vital organs aren’t getting enough oxygen
• anaphylactic shock, a severe form of allergic reaction
• large amounts of blood loss through injury
• blood infections

Medications that can cause low blood pressure

Medications might also cause your blood pressure to become too low. Beta-blockers and nitroglycerin, used to treat heart disease, can have this effect. Diuretics, tricyclic antidepressants, and erectile dysfunction drugs can also cause hypotension. If a medication you’re taking causes your blood pressure to become too low, your doctor may adjust the dosage or change the medication. This usually improves the hypotension.

Hypotension symptoms

Hypotension doesn’t always cause symptoms. But sometimes low blood pressure means your vital organs aren’t receiving as much blood flow as they need. If this happens, you might feel tired or unwell. Symptoms of hypotension may include:

• fatigue, an all-around sense of tiredness or lacking energy
• lightheadedness, or feeling like you might faint
• dizziness, feeling off-balance when you get up from a reclined or seated position, or while you’re standing
• nausea, a sense of discomfort in your stomach and feeling like you want to vomit
• clammy skin, when you feel damp or sweaty to the touch
• depression, persistent feelings such as sadness or low mood that interfere with your daily activities
• loss of consciousness, also known as fainting or syncope
• blurry vision, when your eyesight is out-of-focus or hazy

Treatment for hypotension

Your treatment plan will depend on what’s causing your hypotension. Your doctor will consider factors including:

• the type of hypotension you’re experiencing
• the situations that may be causing hypotension for you

For some people, low blood pressure may not cause any symptoms. In cases where treatment is needed, your doctor may recommend lifestyle changes, medical treatment, or a combination of both.

Lifestyle changes

Sometimes changing certain habits can improve your low blood pressure. The causes of hypotension are different for different people, so your care plan probably won’t include all of these changes. Depending on the specifics of your situation, your doctor might suggest that you:

Stay hydrated

Drink plenty of water to avoid hypotension due to dehydration, especially if you are vomiting or have diarrhea. Stay well hydrated during exercise and when you’re in a hot location. In some cases, your doctor may recommend increasing your electrolyte intake to help keep your blood pressure higher.

Learn your emotional or stress triggers

Make note of the situations where you felt very scared or emotional right before a drop in your blood pressure. You may be able to plan ahead to avoid those situations. Or, you can plan for support in case you become dizzy or feel unwell. If you usually experience low blood pressure when you visit the doctor or dentist, you might consider telling them.

Move around

If you experience low blood pressure when standing for long periods, try flexing your leg muscles and moving in place. If you have the option, take a break to sit down.

Take your time when standing up

Change positions slowly and gradually. Instead of standing up quickly, work your way into a sitting or standing position using small movements. Slow, deep breathing may help keep your blood pressure up.

Change your eating habits

If you experience low blood pressure after eating, your doctor might suggest eating smaller meals more often throughout the day, or eating different foods. Avoid standing up suddenly after eating. There are many ways to manage low blood pressure in your daily life. Your doctor may make other lifestyle suggestions based on your needs.

Medical treatment

Some forms of hypotension may require medical treatment. Medical treatment for low blood pressure can include:

• Medication for an underlying condition. When an underlying condition is causing low blood pressure, your treatment may include medication for that condition. Your doctor may recommend medication for conditions such as heart disease, diabetes, or infection.
• Medication to raise blood pressure. Sometimes, your doctor will prescribe daily medication to raise severely low blood pressure. This is more likely in cases of severe orthostatic hypotension when other treatments have not helped.
• Emergency treatment for shock. Shock-induced hypotension is the most serious form of low blood pressure. Dangerously low blood pressure must be treated immediately. Emergency personnel may give you fluids and other treatments to increase your blood pressure and stabilize your vital signs.

Complications

Hypotension isn’t always a sign of a larger health problem, and it may be treated easily. But for some people, low blood pressure requires treatment to prevent possible complications. Some complications of hypotension are:

Falls and related injuries

A sudden drop in blood pressure may make you feel dizzy, lightheaded, or even lose consciousness (faint). These symptoms can come on quickly, causing falls or other injuries. Falls are a major cause of hospitalization for older adults. Older adults are more likely to experience hypotension after standing up or eating. Treatment and lifestyle changes can help you manage hypotension symptoms.

Shock

If your blood pressure falls dangerously low, your vital organs can start to malfunction because they aren’t receiving enough blood to work properly. This can cause you to go into shock. Symptoms of shock include:

• cool, clammy skin
• a fast or irregular heartbeat
• rapid breathing

Shock is a medical emergency. If you think you or someone else is experiencing shock, call 911 or your local emergency services.

Outlook

Many people can manage low blood pressure by understanding the condition and its symptoms. Learn your triggers, if you have them, and how to manage them. If low blood pressure is making you feel unwell, your doctor may recommend lifestyle changes or medical treatment. If you’re prescribed medication, take it as directed to increase your blood pressure and avoid potentially harmful complications. It’s always best to notify your doctor if you’re concerned about your blood pressure levels and any symptoms you have.