Hypotension is the medical term for low blood pressure, generally defined as a reading below 90/60 mmHg. Blood pressure is measured in two numbers: the top number (systolic) reflects pressure when your heart beats, and the bottom number (diastolic) reflects pressure between beats. When either number consistently falls below that 90/60 threshold and causes symptoms, it’s considered hypotension. For many people, naturally low blood pressure causes no problems at all. It becomes a medical concern when it drops low enough to reduce blood flow to your brain and organs.
How Low Blood Pressure Feels
The most common symptom of hypotension is dizziness or lightheadedness, especially when you stand up quickly. This happens because your brain isn’t getting enough blood in that moment. Other typical symptoms include blurred or fading vision, fatigue, trouble concentrating, nausea, and fainting.
These symptoms can range from mild and occasional to severe enough to interfere with daily life. Some people feel fine at rest but get lightheaded the moment they stand, climb stairs, or spend time in the heat. Others experience a persistent, low-grade fatigue that’s hard to pin down until their blood pressure is checked.
Severe hypotension, the kind that signals a medical emergency, looks different. Confusion, cold and clammy skin, rapid shallow breathing, and a weak pulse all point to dangerously low blood pressure. This level of drop usually results from an acute event like major blood loss, a severe infection, or an allergic reaction, and it requires immediate treatment.
What Causes Blood Pressure to Drop
Blood pressure depends on three things working together: your heart pumping strongly enough, your blood vessels maintaining the right amount of tension, and your body having enough fluid volume. A problem with any one of these can cause hypotension.
Dehydration is one of the most common and easily fixable causes. When your body loses more fluid than it takes in, whether from heat, exercise, vomiting, or diarrhea, your blood volume drops and pressure falls with it. Pregnancy also commonly lowers blood pressure, particularly in the first 24 weeks, because the circulatory system expands rapidly.
Heart conditions that slow or weaken the heartbeat can reduce blood pressure. Hormonal disorders affecting the adrenal or thyroid glands alter the signals that regulate blood vessel tension. Nutritional deficiencies, particularly in vitamin B12, folate, and iron, can lead to low red blood cell counts, which in turn reduce blood pressure. Certain medications are also frequent culprits, especially diuretics (water pills), drugs prescribed for high blood pressure, and some antidepressants.
Types of Hypotension
Orthostatic Hypotension
This is the type you feel when standing up from a seated or lying position. It’s diagnosed when your top number drops by at least 20 mmHg, or your bottom number drops by at least 10 mmHg, within two to five minutes of standing. The sudden shift in gravity pulls blood toward your legs, and your body doesn’t compensate quickly enough. Orthostatic hypotension becomes more common with age, affects people on blood pressure medications, and is especially prevalent in those with nervous system conditions like Parkinson’s disease.
Postprandial Hypotension
Some people experience a significant blood pressure drop after eating. With postprandial hypotension, the top number typically falls about 20 mmHg within 30 to 60 minutes of a meal. This happens because digestion diverts a large volume of blood to the gut. In most healthy people, the body compensates by slightly increasing heart rate and tightening blood vessels elsewhere. When that compensation fails, blood pressure drops and you may feel dizzy or faint shortly after eating. It’s most common in older adults.
Neurally Mediated Hypotension
This form is triggered by a miscommunication between the heart and the brain. When you’ve been standing for a long time, or you experience a strong emotional reaction, your nervous system may paradoxically signal your heart to slow down and your blood vessels to widen, exactly the opposite of what’s needed. The result is a sudden drop in blood pressure and sometimes fainting. Strong emotions, prolonged standing, heat exposure, and even rapid bladder filling can trigger an episode. It’s more common in younger adults and children, and episodes are often preceded by yawning, a feeling of warmth, or rapid breathing.
How Hypotension Is Diagnosed
Diagnosis starts with a simple blood pressure reading, usually taken while you’re sitting and then again while standing. If there’s a notable drop between the two positions, that alone can confirm orthostatic hypotension. Blood tests help identify underlying causes like anemia, thyroid problems, or blood sugar issues.
For people who faint repeatedly without a clear explanation, a tilt table test can be useful. You lie on a padded table secured with straps, and the table is quickly tilted to a near-vertical position to simulate standing. Monitors track your blood pressure, heart rate, and heart rhythm throughout. The test reveals how your cardiovascular and nervous systems respond to the positional change. Before ordering it, providers typically rule out structural heart problems or rhythm abnormalities first.
Managing Low Blood Pressure
Treatment depends entirely on the cause. If a medication is driving your blood pressure too low, adjusting the dose or switching to an alternative often resolves the problem. If dehydration is the issue, increasing fluid intake is the straightforward fix.
For chronic or recurring hypotension, several lifestyle strategies help. Increasing salt intake is one of the more counterintuitive recommendations, since most health advice tells you to eat less salt. People with low blood pressure may benefit from consuming at least 6 grams of salt per day, roughly double what’s recommended for the general population. Salt tablets are sometimes preferred over simply eating salty foods because they allow more precise dosing.
Drinking more water throughout the day supports blood volume. Eating smaller, more frequent meals can prevent the large blood flow shifts that cause postprandial drops. Limiting alcohol helps, since alcohol widens blood vessels and promotes fluid loss. Regular exercise, particularly lower-body strength training, improves circulation and helps your blood vessels respond more efficiently to position changes.
Simple physical maneuvers make a real difference for orthostatic hypotension. Rising slowly from bed or a chair, sitting on the edge of the bed for a minute before standing, and crossing your legs or tensing your thigh muscles while standing all help push blood back toward your heart and brain. Compression stockings that reach waist height can also prevent blood from pooling in the legs.
When Low Blood Pressure Isn’t a Problem
Plenty of people walk around with blood pressure readings below 90/60 and feel perfectly fine. Athletes, in particular, often have naturally low resting blood pressure as a sign of cardiovascular fitness. If you’re not experiencing dizziness, fainting, fatigue, or any other symptoms, a low reading on its own isn’t cause for concern. Hypotension only matters clinically when it causes symptoms or signals an underlying condition that needs attention.