Low blood pressure, also called hypotension, is a condition where blood flows through your arteries at pressures lower than what is considered normal. While many people with low blood pressure feel perfectly fine, others experience dizziness, fainting, and weakness that can interfere with daily life. Understanding this condition helps you recognize when to seek help and how to manage symptoms effectively.

Understanding Blood Pressure Numbers

Blood pressure is measured using two numbers that tell us how hard blood pushes against artery walls as it moves through your body. The first number, called systolic pressure, represents the force when your heart beats and pumps blood out. The second number, called diastolic pressure, shows the pressure between heartbeats when your heart rests. These numbers are recorded in millimeters of mercury, written as mm Hg.^[1]

A normal blood pressure reading typically falls between 90/60 mm Hg and 120/80 mm Hg. When your blood pressure drops below 90/60 mm Hg, doctors consider it low blood pressure. However, what counts as too low varies from person to person. Some individuals naturally have lower blood pressure and feel completely healthy, while others may experience uncomfortable or even dangerous symptoms at the same reading.^[1][3]

How Common Is Low Blood Pressure

Because many people with low blood pressure never experience symptoms, it’s difficult to know exactly how many people are affected. Many individuals discover their blood pressure is low only during routine medical checkups. Among those who do have symptoms, low blood pressure becomes more common with age.^[2]

A specific type of low blood pressure called orthostatic hypotension (which happens when you stand up) affects about 5 percent of people at age 50. This number increases dramatically with age, affecting more than 30 percent of people over 70 years old. This age-related increase happens because the body’s automatic systems that control blood pressure become less responsive over time.^[2][15]

In one study of people older than 65 years, researchers found that 18 percent had orthostatic hypotension, but only 2 percent of these individuals experienced symptoms. This shows that many older adults live with low blood pressure without even knowing it.^[1]

What Causes Low Blood Pressure

Low blood pressure can develop for many different reasons. Sometimes the cause is straightforward, while other times it results from complex interactions between multiple body systems. Understanding the cause is essential for proper treatment.^[1]

Dehydration is one of the most common causes of low blood pressure. When your body loses too much fluid, the volume of blood circulating through your vessels decreases. This means less fluid is pushing against artery walls, causing pressure to drop. Dehydration can happen from not drinking enough water, excessive sweating, vomiting, diarrhea, or using medications called diuretics that increase urination.^[5][7]

Heart problems can prevent your heart from pumping blood effectively. Conditions like heart failure, heart valve disease, extremely slow heart rate (called bradycardia), or irregular heart rhythms (called arrhythmias) may all lead to low blood pressure because the heart cannot maintain adequate blood flow throughout the body.^[2][7]

Hormonal problems affecting the endocrine system can also cause low blood pressure. For example, an underactive thyroid gland (called hypothyroidism), low blood sugar (called hypoglycemia), or Addison’s disease (where the adrenal glands don’t produce enough hormones) can all interfere with blood pressure regulation.^[7][8]

Serious infections, particularly when bacteria enter the bloodstream (a condition called septicemia), can cause blood pressure to plummet to dangerously low levels. This happens because the infection causes widespread inflammation that affects how blood vessels work. Blood loss from injury, surgery, or internal bleeding also causes sudden drops in blood pressure because there is simply less blood to circulate.^[2][7]

Pregnancy commonly causes blood pressure to drop because a woman’s circulatory system expands rapidly during early pregnancy. This is usually temporary and blood pressure typically returns to normal after delivery.^[1][8]

Problems with the autonomic nervous system, which automatically controls many body functions including blood pressure, can prevent the body from adjusting blood pressure properly. Conditions like Parkinson’s disease or diabetes can damage these nerve pathways over time.^[1][7]

Risk Factors for Developing Low Blood Pressure

Certain groups of people face higher risks of developing low blood pressure. Age is a significant factor. Older adults are more vulnerable because the sensors in their blood vessels that monitor pressure become less sensitive over time. These sensors normally trigger rapid adjustments when you change position, but they work less efficiently as you age.^[2]

People who are very physically active and fit may naturally have lower blood pressure without any symptoms. Athletes and younger individuals who exercise regularly often have readings below 90/60 mm Hg and feel completely normal. For them, this is not a medical concern.^[2]

Anyone taking multiple medications, particularly older adults, faces increased risk. The more medications you take, the higher the chance that one or a combination might lower blood pressure too much. People with chronic conditions like diabetes, Parkinson’s disease, or heart disease are also at higher risk because these conditions affect how the body regulates blood pressure.^[1][7]

Long periods of bed rest, such as during recovery from surgery or serious illness, can lead to low blood pressure. When you lie down for extended periods, your body’s blood pressure regulation systems become less active and may not respond properly when you finally stand up.^[8]

Types of Low Blood Pressure

Low blood pressure comes in several different forms, each with its own patterns and triggers. Understanding which type you have helps guide treatment decisions.^[1]

Orthostatic hypotension, also called postural hypotension, is the most common type. This occurs when blood pressure drops suddenly upon standing up from sitting or lying down. Normally, when you stand, gravity pulls blood down into your legs. Your body should quickly compensate by narrowing blood vessels and increasing heart rate to maintain blood flow to your brain. With orthostatic hypotension, this adjustment either doesn’t happen or happens too slowly. The diagnosis requires that systolic pressure drops by at least 20 mm Hg or diastolic pressure drops by at least 10 mm Hg within three minutes of standing.^[1][2]

A related condition called postprandial hypotension causes blood pressure to drop one to two hours after eating, especially after large meals high in carbohydrates. This happens because blood flow increases to the digestive system to help with digestion. In some people, particularly older adults or those with nervous system disorders like Parkinson’s disease, the body cannot adequately compensate for this shift in blood flow.^[1][8]

Neurally mediated hypotension occurs after standing for long periods. It’s thought to happen because of a miscommunication between the brain and heart. This type is more common in younger people and children, who usually outgrow it over time.^[1][7]

Symptoms That Signal Low Blood Pressure

Many people with low blood pressure never experience any symptoms and only discover their condition during routine medical checkups. For others, symptoms can range from mildly annoying to severely debilitating or even dangerous.^[2]

Dizziness and lightheadedness are the most common symptoms. You might feel like the room is spinning or that you’re about to lose your balance. These sensations happen because your brain isn’t receiving enough blood flow and oxygen. Some people describe feeling like they’re floating or disconnected from their surroundings.^[2][6]

Fainting, medically called syncope, occurs when blood pressure drops so low that your brain temporarily shuts down to protect itself. You might feel fainting coming on as increasing dizziness and a narrowing of vision, or it might happen suddenly without warning. Fainting can be dangerous because you might fall and injure yourself.^[2][6]

Vision problems are common symptoms. Your vision might become blurred or you might see spots or darkness. Some people describe their vision as “graying out” or becoming dim, as if someone is lowering the lights. This happens because the eyes need consistent blood flow to function properly.^[2][6]

Weakness and fatigue make you feel tired and lacking in energy. Your muscles might feel weak or heavy, making even simple tasks feel exhausting. This occurs because your muscles and organs aren’t getting enough oxygen-rich blood to function at their best.^[2][11]

Other symptoms include nausea or vomiting, rapid shallow breathing, confusion or difficulty concentrating, and changes in behavior. Your skin might look paler than usual and feel cold or clammy to the touch. Some people experience an unusually fast heartbeat as their heart tries to compensate for low pressure by beating more rapidly.^[2][11]

Preventing Low Blood Pressure

While not all cases of low blood pressure can be prevented, several strategies can help reduce your risk or minimize symptoms. These approaches focus on supporting your body’s natural blood pressure regulation systems.^[6]

Staying well hydrated is crucial. Drinking plenty of water throughout the day maintains your blood volume and helps prevent pressure from dropping too low. Clear liquids work best. However, if you have kidney, heart, or liver disease that requires limiting fluids, you should discuss appropriate fluid intake with your doctor before increasing consumption.^[6][13]

Moving carefully when changing positions can prevent sudden drops in blood pressure. When getting up from bed, roll to your side first and swing your legs over the edge. Sit for a moment before slowly standing up. When rising from a chair, take your time and consider crossing and uncrossing your legs a few times before standing, as this helps pump blood back toward your heart.^[13][14]

Eating smaller, more frequent meals instead of large ones can help prevent postprandial hypotension. Large meals, especially those rich in carbohydrates, require significant blood flow to the digestive system. Smaller meals reduce this demand. Avoiding alcohol is also helpful because it can make low blood pressure worse by causing your body to lose water and dilating blood vessels.^[6][13]

Wearing compression stockings helps improve blood flow by preventing blood from pooling in your legs. These special stockings squeeze your legs gently, helping push blood back up toward your heart and brain. They can be particularly helpful for people with orthostatic hypotension.^[6][13]

Avoiding prolonged standing or sitting is important. If you must stand for long periods, try to keep moving by shifting your weight from foot to foot or walking in place. When sitting at a desk or watching television, take regular breaks to move around and keep blood flowing properly.^[13][14]

Elevating the head of your bed by four to six inches can help prevent morning symptoms of low blood pressure. You can do this by placing blocks under the bed legs at the head of the bed or using wedges under the mattress. Extra pillows alone usually don’t work as well because they can slip during sleep.^[14]

Adding more salt to your diet may help raise blood pressure, but only do this if your doctor recommends it. Too much salt can cause other health problems, particularly if you have certain medical conditions. Your doctor can advise whether increasing salt intake is safe and appropriate for you.^[6][13]

How Blood Pressure Regulation Works in Your Body

Understanding how your body normally maintains blood pressure helps explain what goes wrong in hypotension. Blood pressure control is an automatic process involving multiple systems working together constantly, making continuous tiny adjustments you never notice.^[5]

When you stand up, gravity immediately pulls about 500 to 1,000 milliliters of blood down into your legs and lower body. This is roughly equivalent to two to four cups of blood suddenly moving away from your heart and brain. Without rapid compensation, this would cause severe dizziness or fainting every time you stood up.^[16]

Special sensors called baroreceptors in your neck and above your heart constantly monitor blood pressure. When they detect a drop, they immediately send signals through the autonomic nervous system to make adjustments. The heart beats faster and more forcefully to pump more blood. Blood vessels throughout your body, especially in your legs, narrow to reduce their capacity and push blood upward. Your body also releases hormones that help tighten blood vessels and retain fluid.^[5][7]

In healthy individuals, these adjustments happen within seconds. Your systolic pressure might drop by only 5 to 10 mm Hg and your diastolic pressure might actually rise slightly by 5 to 10 mm Hg. Your pulse increases by about 10 to 25 beats per minute. These changes maintain adequate blood flow to your brain and other vital organs.^[16]

With hypotension, something interferes with this automatic adjustment process. The baroreceptors might not detect pressure changes quickly enough, especially in older adults. The nervous system might not send signals properly, particularly in people with diabetes or Parkinson’s disease. The heart might not be able to pump more forcefully due to heart disease. Blood vessels might not be able to constrict adequately, sometimes because of medications. Or there might not be enough fluid volume to work with, as happens with dehydration.^[5][7]

When these compensatory mechanisms fail, blood pressure stays too low for too long. Vital organs, particularly the brain, don’t receive enough oxygen-rich blood. The brain is especially sensitive because it sits at the top of the body, working against gravity. Even a brief reduction in blood flow can cause dizziness, confusion, or fainting. Prolonged inadequate blood flow can damage organs over time.^[3][5]

After eating, blood flow naturally increases to your digestive system to help process food. Your body usually compensates by making the adjustments described above. However, in some people, particularly older adults, these adjustments aren’t sufficient after large meals. The digestive system “steals” too much blood from other parts of the body, causing postprandial hypotension.^[1]