Low blood pressure, called hypotension, is generally a reading below 90/60 mmHg. The first number (systolic) measures pressure when your heart beats, and the second (diastolic) measures pressure between beats. Unlike high blood pressure, low blood pressure isn’t defined by a single cutoff for everyone. What matters most is whether it causes symptoms and how quickly it drops.
Some people walk around with naturally low readings and feel perfectly fine. Athletes and people who exercise regularly often have lower resting blood pressure as a sign of cardiovascular fitness. Low blood pressure only becomes a medical concern when it causes noticeable symptoms or signals an underlying problem.
How It Feels
When blood pressure drops too low, certain parts of your body don’t get enough blood flow. Your body normally compensates automatically, either by speeding up your heart rate or tightening blood vessels. Symptoms appear when your body can’t keep up with the drop.
The most common signs include:
- Dizziness or lightheadedness, especially when standing up
- Fainting or feeling like you might pass out
- Blurred or distorted vision
- Nausea
- Fatigue, weakness, or feeling sluggish
- Fast, shallow breathing
- Confusion or trouble concentrating
These symptoms can range from mildly annoying to disabling, depending on how far and how fast the pressure drops. A gradual, small dip might just make you feel a little off. A sudden, steep drop can cause you to faint and injure yourself.
Common Causes
Dehydration is one of the most frequent triggers. When your body loses more fluid than it takes in, your total blood volume drops, and so does pressure. Fever, vomiting, severe diarrhea, heavy sweating during exercise, and overuse of water pills can all lead to dehydration significant enough to lower blood pressure.
Pregnancy commonly lowers blood pressure, particularly during the first 24 weeks, because the circulatory system expands rapidly. Long-term bed rest also reduces blood pressure because the body deconditions and blood vessels lose their tone. Significant blood loss from an injury or internal bleeding causes a sharp, dangerous drop in pressure by reducing blood volume directly.
Heart conditions that slow the heart rate, damage heart valves, or weaken the heart muscle can reduce the amount of blood pumped with each beat. Endocrine disorders affecting the thyroid or adrenal glands also play a role, as do nutritional deficiencies in vitamin B12, folate, and iron, which can lead to anemia and lower blood pressure as a result.
Medications That Lower Blood Pressure
Several types of medications lower blood pressure as either their intended effect or a side effect. Diuretics (water pills) reduce blood volume. Beta-blockers slow the heart rate. Drugs prescribed for Parkinson’s disease, depression, and erectile dysfunction can also cause drops. If you’ve recently started or increased a medication and notice dizziness or lightheadedness, that connection is worth flagging to your prescriber.
Types of Low Blood Pressure
Orthostatic hypotension is the most common type. It happens when blood pressure drops by 20 mmHg systolic or 10 mmHg diastolic within three minutes of standing up. Blood pools in your legs when you rise, and your body doesn’t constrict blood vessels fast enough to compensate. This is especially common in older adults and is worsened by heat, alcohol, dehydration, and deconditioning from lack of activity.
Postprandial hypotension is a drop that occurs within one to two hours after eating. Large, carbohydrate-heavy meals are the biggest trigger because digestion diverts a significant amount of blood to the gut. This type mostly affects older adults, particularly those who already have high blood pressure or conditions affecting the autonomic nervous system, like Parkinson’s disease.
Neurally mediated hypotension is a pressure drop triggered by standing for long periods. It mostly affects young adults and children. The brain and heart miscommunicate: the heart signals that blood pressure is too high when it’s actually dropping, causing the body to lower it further.
How It’s Diagnosed
Diagnosis starts with a standard blood pressure reading, but finding the cause often requires more investigation. Your provider will likely check blood work to look for anemia, blood sugar problems, or thyroid issues. An electrocardiogram can reveal heart rhythm problems or structural issues that might explain the low readings.
If you’ve fainted multiple times without a clear explanation, a tilt table test may be recommended. You lie flat on a table that tilts you to an upright position while monitors track your blood pressure and heart rate in real time. A “positive” result means the position change triggered a large drop in pressure or a spike in heart rate, pointing toward orthostatic hypotension, vasovagal syncope, or a related condition. Providers typically rule out heart-related causes first before ordering this test.
Lifestyle Changes That Help
For many people, managing low blood pressure doesn’t require medication. Small, consistent changes to daily habits can make a real difference.
Drink more fluids. Water increases blood volume, which directly supports blood pressure. Aim to stay well-hydrated throughout the day, and limit alcohol, which is dehydrating and lowers blood pressure even in moderate amounts.
Add salt strategically. While most health advice tells you to cut sodium, people with low blood pressure may benefit from a bit more. Salt raises blood pressure by helping the body retain fluid. That said, too much sodium can strain the heart over time, so this is a change worth discussing with a provider rather than doing aggressively on your own.
Eat smaller, lower-carb meals. Large meals rich in potatoes, rice, pasta, and bread are the main triggers for postprandial drops. Eating smaller portions spread across the day keeps blood flow more evenly distributed and prevents that post-meal slump.
Move positions slowly. When getting out of bed or standing up from a chair, take your time. Sit at the edge of the bed for a moment before standing. Don’t sit with your legs crossed, which restricts blood flow from the legs back to the heart.
Try compression stockings. Elastic compression stockings push blood from the legs back toward the heart, reducing the pooling that causes orthostatic symptoms. Some people find an abdominal compression belt easier to tolerate and similarly effective.
Use a quick fix when symptoms hit. If you start feeling lightheaded while standing, cross your legs tightly and squeeze, or put one foot up on a chair and lean forward. Both moves push blood from the legs back to the heart and can buy you enough time to avoid fainting.
Exercise regularly. Working toward about 150 minutes of moderate aerobic activity per week improves vascular tone and helps your body regulate blood pressure more effectively. Avoid exercising in hot, humid conditions, which can worsen drops.
A cup or two of caffeinated coffee or tea in the morning can also provide a temporary boost. Caffeine constricts blood vessels slightly, which raises pressure. Just balance it with extra water, since caffeine is mildly dehydrating.
When Low Blood Pressure Is Dangerous
Most cases of low blood pressure are manageable and not life-threatening. But a sudden, severe drop can lead to shock, which is a medical emergency. Shock occurs when organs don’t receive enough blood to function. It can result from serious bleeding, severe infections (sepsis), or severe allergic reactions (anaphylaxis).
Signs that low blood pressure has become dangerous include cold and clammy skin, rapid and shallow breathing, a weak and fast pulse, confusion, and loss of consciousness. In critical care settings, medical teams aim to keep mean arterial pressure at or above 65 mmHg to ensure vital organs are receiving adequate blood flow. If you or someone near you shows these signs, it’s a situation that requires emergency care immediately.