Hypotension is the medical term for low blood pressure. It means the force of blood pushing against your artery walls is lower than what’s typically expected. A blood pressure reading below 90/60 mmHg is generally considered hypotension. For many people, naturally low blood pressure causes no problems at all. It only becomes a medical concern when it drops enough to cause symptoms like dizziness, fainting, or fatigue.
How Blood Pressure Works
Your blood pressure reading has two numbers. The top number (systolic) measures the pressure when your heart pumps blood out. The bottom number (diastolic) measures the pressure between beats, when your heart is resting. A typical healthy reading falls around 120/80 mmHg. When either number drops significantly below the 90/60 threshold, your body may not push enough blood to your brain and organs.
Two main factors determine your blood pressure at any given moment: how much blood your heart pumps with each beat (cardiac output) and how much resistance your blood vessels create. If your heart pumps less blood, or if your blood vessels widen and offer less resistance, your pressure drops. Your nervous system constantly adjusts both of these to keep blood flowing where it needs to go. When that balancing act fails, hypotension results.
Common Symptoms
Mild hypotension often produces no noticeable symptoms. Many people live with blood pressure readings below 90/60 and feel perfectly fine. When symptoms do appear, they typically include dizziness or lightheadedness, blurred vision, fatigue, difficulty concentrating, and nausea. Fainting is one of the more obvious signs, and it carries a real injury risk from falls, particularly for older adults.
Severe hypotension is a different situation entirely. When blood pressure drops sharply, it can lead to shock, where your organs aren’t getting enough blood to function. Signs of shock include confusion (especially in older people), cold and clammy skin, pale skin color, rapid and shallow breathing, and a weak but fast pulse. This is a medical emergency.
Types of Hypotension
Not all low blood pressure behaves the same way. The type you have depends on when and why it happens.
Orthostatic hypotension is the most common type. It happens when your blood pressure drops after you stand up. The formal definition is a sustained drop of at least 20 mmHg in systolic pressure or 10 mmHg in diastolic pressure within three minutes of standing. Symptoms tend to be worst first thing in the morning because your body loses fluid volume overnight. Heat, alcohol, dehydration, and prolonged bed rest all make it worse.
Postprandial hypotension is a blood pressure drop that occurs within two hours of eating. Large meals and meals high in carbohydrates are the most common triggers. After you eat, blood flows to your digestive system to help with absorption. Normally your body compensates by increasing heart rate and tightening blood vessels elsewhere, but in some people, especially older adults, that compensation falls short.
Neurally mediated hypotension happens when a miscommunication between your heart and brain causes blood pressure to drop. It often occurs after standing for long periods, during emotional stress, or in hot environments. This is a common cause of fainting in younger, otherwise healthy people.
What Causes Low Blood Pressure
The list of potential causes is long because so many things influence how your heart and blood vessels behave. Temporary causes include dehydration, blood loss, severe infection, and allergic reactions. Pregnancy commonly lowers blood pressure because the circulatory system expands rapidly during the first and second trimesters.
Heart conditions like extremely slow heart rate, heart valve problems, and heart failure can all reduce the amount of blood your heart pumps. Endocrine disorders, including thyroid problems and adrenal insufficiency, affect hormones that help regulate blood pressure. Nutritional deficiencies in vitamin B12 and folate can reduce red blood cell production, which in turn lowers pressure.
Medications are one of the most frequent culprits. Diuretics (water pills), many blood pressure medications, and several classes of antidepressants can cause hypotension as a side effect. Older antidepressants known as MAOIs are particularly likely to cause orthostatic hypotension in a dose-related way. Even some newer antidepressants, including bupropion and mirtazapine, can occasionally trigger drops in blood pressure upon standing, especially in people with existing heart conditions.
How Hypotension Is Diagnosed
Diagnosis starts with a simple blood pressure reading, but identifying the type and cause often requires more investigation. Your blood pressure may be checked while you’re sitting, lying down, and standing to see how it changes with position. Blood tests can help rule out anemia, blood sugar problems, and thyroid disorders.
For people who faint or get dizzy frequently, a tilt table test is one of the key diagnostic tools. You lie flat on a padded table, strapped in securely, and the table is tilted to about a 70-degree angle within roughly 10 seconds, simulating a quick transition to standing. Monitors track your blood pressure, heart rate, and heart rhythm throughout. A “positive” result means you experienced symptoms like dizziness or fainting along with a significant drop in blood pressure, which can help confirm orthostatic hypotension, vasovagal syncope, or related conditions.
Managing Low Blood Pressure
If your low blood pressure doesn’t cause symptoms, it generally doesn’t need treatment. In fact, naturally low blood pressure is associated with better long-term cardiovascular health. Treatment becomes necessary when symptoms affect your daily life or put you at risk for falls and injury.
Lifestyle adjustments are the first line of management. Increasing your fluid intake helps expand blood volume, and adding more salt to your diet can help your body retain that fluid. There are no universal guidelines on exactly how much sodium to add, but the goal is to find the amount that reduces your symptoms without overshooting into high blood pressure territory. Eating smaller, lower-carbohydrate meals can help prevent postprandial drops. Avoiding alcohol, which widens blood vessels and promotes dehydration, also helps.
Physical strategies make a meaningful difference for orthostatic hypotension specifically. Rising slowly from sitting or lying positions gives your body time to adjust. Wearing compression stockings helps prevent blood from pooling in your legs. Avoiding prolonged standing, crossing your legs while standing, and tensing your leg muscles before getting up are all simple techniques that can keep blood pressure from dropping too quickly.
When a medication is causing low blood pressure, adjusting the dose or switching to an alternative is often enough to resolve the problem. For persistent cases that don’t respond to lifestyle changes, prescription medications that either increase blood volume or tighten blood vessels are available.
When Low Blood Pressure Becomes Dangerous
The biggest immediate risk of hypotension is fainting and the injuries that follow. A fall can mean a broken hip, a head injury, or worse, particularly in older adults. Over time, repeated episodes of significantly low blood pressure may reduce blood flow to organs, though this is primarily a concern in severe or shock-level cases rather than mild chronic hypotension.
The symptoms that signal a true emergency are confusion, cold or clammy skin, rapid shallow breathing, and a weak rapid pulse. These suggest your blood pressure has dropped low enough that your organs are being deprived of adequate blood flow. This requires immediate emergency care.