Low blood pressure, called hypotension, is generally a reading below 90/60 mmHg. While normal blood pressure sits below 120/80 mmHg according to the latest 2025 American Heart Association guidelines, there’s no official cutoff where “low” begins the way there is for high blood pressure. Instead, low blood pressure is typically defined by whether your numbers drop enough to cause symptoms.
What the Numbers Mean
A blood pressure reading has two numbers. The top number (systolic) measures the force when your heart pumps. The bottom number (diastolic) measures the pressure between beats. Most clinicians consider blood pressure low when systolic drops below 90 or diastolic drops below 60, but some people naturally run lower without any problems.
The key distinction is whether low readings come with symptoms. A systolic pressure of 85 in someone who feels fine is usually not a concern. The same number in someone who feels dizzy and confused is a different situation entirely. Blood pressure is the product of two things: how much blood your heart pumps per minute and how much resistance your blood vessels create. When either of those drops significantly, pressure falls.
Common Symptoms
When blood pressure falls low enough to reduce blood flow to the brain and organs, you may notice lightheadedness or dizziness, especially when standing up. Blurred vision, fatigue, nausea, and difficulty concentrating are also common. Some people feel generally “off” without being able to pinpoint why. In more pronounced drops, fainting (syncope) can occur.
Severe hypotension looks different. Rapid, shallow breathing, cold and clammy skin, confusion, pale skin, weak pulse, and very low urine output are signs that organs aren’t getting enough blood. This is a medical emergency.
Types of Low Blood Pressure
Orthostatic Hypotension
This is the most recognizable type: a sudden drop when you stand up from sitting or lying down. The clinical definition is a sustained fall of at least 20 mmHg systolic or 10 mmHg diastolic within three minutes of standing. A milder version, called initial orthostatic hypotension, involves a sharper but very brief drop (over 40 mmHg systolic) within the first 15 to 30 seconds of standing, caused by a temporary mismatch between how much blood your heart is pumping and how quickly your blood vessels can tighten. Dehydration, prolonged bed rest, pregnancy, and certain medications all make it more likely.
Postprandial Hypotension
Blood pressure can drop within two hours of eating, particularly after large meals or meals high in carbohydrates. Digestion draws blood to the gut, and in some people, the body doesn’t compensate well enough to maintain pressure elsewhere. Alcohol with a meal makes this worse. It’s most common in older adults.
Neurally Mediated Hypotension
This type involves a miscommunication between the heart and brain, often triggered by standing for long periods. The brain mistakenly signals the heart to slow down, dropping blood pressure. It’s a common cause of fainting in younger, otherwise healthy people.
What Causes It
Low blood pressure has a wide range of causes, from harmless to serious. Dehydration is one of the most common and most easily fixed. When you lose more fluid than you take in (through sweating, vomiting, diarrhea, or simply not drinking enough), blood volume drops and pressure follows.
Heart conditions can reduce the amount of blood pumped with each beat. Heart valve problems, heart failure, and an unusually slow heart rate all lower cardiac output, which directly lowers pressure. Hormone-related conditions play a role too. Addison’s disease, which affects the adrenal glands, can cause blood pressure to fall. Low blood sugar and diabetes may also contribute.
Medications are a frequently overlooked cause. Diuretics (water pills), drugs for high blood pressure, certain antidepressants, and medications for erectile dysfunction can all push blood pressure lower than intended. Pregnancy commonly lowers blood pressure as well. Blood pressure typically dips during the first and second trimesters, reaching its lowest point around weeks 17 to 20, before rising again in the third trimester. In normal pregnancies, a first-trimester systolic reading around 112 and diastolic around 65 is typical.
Serious, sudden drops in blood pressure point to emergencies: severe infection (sepsis), a major allergic reaction (anaphylaxis), or significant blood loss. These conditions cause blood vessels to widen dramatically or drain blood volume, overwhelming the body’s ability to compensate.
When Low Blood Pressure Becomes Dangerous
The danger threshold isn’t a single number. It depends on how fast pressure drops and how well the body compensates. In shock, the body goes through recognizable stages. Early on, with roughly a 10% loss of blood volume, the body can maintain blood flow to vital organs by tightening blood vessels. You might feel mildly dizzy but otherwise okay.
At a 20% to 25% loss, those compensatory mechanisms get overwhelmed. Heart rate climbs above 100 beats per minute, skin becomes cool and clammy, and urine output drops. Beyond 30% to 40% blood volume loss, systolic pressure falls below 90, mental status changes significantly, and organ damage becomes a real risk. At greater than 40% loss, systolic pressure drops well below 90, heart rate exceeds 120, and skin becomes pale and cold. Without treatment, this progresses to organ failure.
These stages apply to blood loss specifically, but the pattern is similar in other forms of shock. The point is that your body has a buffer, but once that buffer is exceeded, things deteriorate quickly.
Managing Low Blood Pressure at Home
For chronic, mild low blood pressure, several lifestyle adjustments can make a meaningful difference. Increasing fluid intake raises blood volume and helps prevent the dehydration that contributes to many cases. Water is the best choice. Alcohol is dehydrating and lowers blood pressure even in moderate amounts.
Salt is one area where advice for low blood pressure is the opposite of what most people hear. Adding more sodium to your diet can raise blood pressure, which is helpful if yours runs too low. That said, excess sodium carries its own risks, particularly for heart health in older adults, so this is a change worth discussing with your doctor rather than doing aggressively on your own.
Other practical strategies help, especially for orthostatic hypotension. Standing up slowly gives your cardiovascular system time to adjust. Crossing your legs or tensing your thigh muscles before standing can help push blood upward. Eating smaller, lower-carbohydrate meals reduces postprandial drops. Wearing compression stockings prevents blood from pooling in the legs.
Medical Treatment Options
When lifestyle changes aren’t enough, medications can help. The most commonly used options work by either increasing blood volume or tightening blood vessels. One approach uses a medication that mimics a hormone your body naturally produces to retain sodium and water, expanding blood volume. Another directly stimulates receptors on blood vessel walls, causing them to constrict and raising pressure. A third works by boosting levels of a nervous system chemical that tightens blood vessels, particularly useful for people with neurological conditions that impair the body’s automatic blood pressure regulation.
If a medication you’re already taking is causing low blood pressure, your provider may adjust the dose or switch to an alternative. This is especially common with blood pressure medications, where the goal of treating hypertension can overshoot into hypotension.
For most people with chronically low blood pressure that causes mild symptoms, the combination of increased fluids, adjusted salt intake, and mindful movement habits is enough to keep symptoms manageable. The priority shifts to identifying and treating an underlying cause when blood pressure drops are sudden, severe, or worsening over time.