Low blood pressure, called hypotension, means your heart isn’t pushing blood through your body with enough force to keep everything running smoothly. It’s generally defined as a reading below 90/60 mmHg. For many people, naturally low blood pressure causes zero problems and may even be a sign of good cardiovascular fitness. But when it drops low enough to cause symptoms like dizziness, fainting, or fatigue, it signals that your brain and organs aren’t getting the blood flow they need.
How Low Blood Pressure Feels
The tricky thing about low blood pressure is that plenty of people have it without ever knowing. If your readings consistently sit below 90/60 but you feel fine, there’s generally nothing to worry about. The concern starts when your body tells you something is off.
Common symptoms include dizziness or lightheadedness, blurred or fading vision, nausea, trouble concentrating, and a general sense of fatigue that doesn’t match your activity level. Fainting is the most dramatic sign, and it often comes after standing up quickly or being on your feet for a long time. Some people describe a “graying out” of their vision before it happens.
When blood pressure drops severely, it can progress to shock, which is a medical emergency. Signs of shock look different from ordinary lightheadedness: cold, clammy skin that may appear pale or bluish (especially around the lips or fingernails), rapid shallow breathing, a weak and fast pulse, and confusion, particularly in older adults. If you or someone near you shows these signs, that’s a situation requiring immediate emergency care.
Why Blood Pressure Drops
Low blood pressure isn’t a single condition. It has several distinct patterns, each with its own triggers.
Orthostatic Hypotension
This is the most common type people notice. It happens when you stand up and your blood pressure falls by at least 20 points systolic (the top number) or 10 points diastolic (the bottom number) within three minutes. Normally, your nervous system compensates almost instantly when you shift from sitting to standing, tightening blood vessels in your legs to push blood back up toward your brain. When that reflex fails or lags, blood pools in your lower body and you feel dizzy or faint. Dehydration, prolonged bed rest, and aging all make this more likely.
Postprandial Hypotension
Some people experience a blood pressure drop after eating, especially large meals. Digestion redirects a significant amount of blood to your stomach and intestines. In most people, the body compensates by increasing heart rate and constricting other blood vessels. When that compensation falls short, blood pressure dips noticeably within one to two hours of a meal. This pattern is most common in older adults.
Neurally Mediated Hypotension
Sometimes called neurocardiogenic syncope, this type causes sudden, unexpected drops in blood pressure while standing, often after long periods on your feet or in response to emotional stress, heat, or pain. It doesn’t follow the same predictable pattern as orthostatic hypotension. Instead, it strikes in episodes, and it’s a common cause of fainting in otherwise healthy younger people.
Medications That Can Lower Blood Pressure
Drugs are one of the most frequent causes of low blood pressure, especially in people taking more than one medication. Several broad categories are known to contribute:
- Blood pressure medications: This includes diuretics (both thiazide and loop types), calcium channel blockers, and angiotensin receptor blockers. These drugs are designed to lower blood pressure, so overshooting the target is a common side effect, particularly when doses change or you become dehydrated.
- Heart medications: Beta blockers can slow the heart rate and reduce blood pressure simultaneously. Nitrate-based drugs used for chest pain are a particularly common cause of sudden drops.
- Alpha blockers: Often prescribed for prostate issues, these commonly cause severe orthostatic hypotension because they relax blood vessel walls.
- Antidepressants: Older tricyclic antidepressants and MAOIs are well-known culprits. MAOIs in particular can cause severe orthostatic hypotension. Newer antidepressants like SNRIs also commonly contribute, while SSRIs do so only rarely.
- Parkinson’s disease drugs: Dopamine-related medications used for Parkinson’s frequently cause orthostatic hypotension as a side effect.
- Antipsychotic medications: All drugs in this class carry some risk of lowering blood pressure upon standing.
If you suspect a medication is causing your symptoms, don’t stop taking it on your own. A dosage adjustment or timing change often resolves the problem without sacrificing the drug’s benefit.
Other Common Causes
Beyond medications, several conditions and situations can push blood pressure lower than normal. Dehydration is one of the simplest and most common. When you lose more fluid than you take in, whether from heat, exercise, illness, or simply not drinking enough, your blood volume drops and pressure falls with it.
Pregnancy commonly lowers blood pressure, especially during the first 24 weeks, as the circulatory system expands rapidly to supply the growing fetus. Endocrine problems like thyroid disorders or adrenal insufficiency can reduce blood pressure because hormones play a direct role in regulating how tightly your blood vessels constrict. Heart conditions such as very slow heart rate, heart valve problems, or heart failure can reduce the volume of blood pumped with each beat. Significant blood loss from an injury or internal bleeding causes a rapid and dangerous drop.
Nutritional deficiencies matter too. Not getting enough vitamin B12 or folate can lead to anemia, which means fewer red blood cells to carry oxygen. Your body compensates by lowering vascular resistance, and blood pressure drops as a result.
How Low Blood Pressure Is Diagnosed
A standard blood pressure reading is the starting point, but a single reading doesn’t tell the whole story. If your symptoms mainly happen when you stand up, your provider will likely check your blood pressure both while you’re lying down and after you’ve been standing for a few minutes. A drop of 20 points systolic or 10 points diastolic within three minutes of standing confirms orthostatic hypotension.
For episodes that are harder to pin down, a tilt table test can recreate the conditions that trigger symptoms. You lie flat on a padded table, securely strapped in, and the table is tilted to about a 70-degree angle within roughly 10 seconds, simulating a sudden shift to standing. You stay upright for up to 45 minutes while monitors track your blood pressure, heart rate, and heart rhythm. A positive result means your blood pressure dropped significantly or you developed symptoms like dizziness or fainting during the tilt. A negative result, where your body adjusts normally, helps rule out certain causes.
Blood tests may be ordered to check for anemia, blood sugar abnormalities, or thyroid and adrenal function, depending on what your symptoms suggest.
Managing Low Blood Pressure Day to Day
When low blood pressure causes symptoms, management focuses on keeping blood volume up and helping your body adjust to position changes. For many people, simple lifestyle adjustments make a meaningful difference without any medication.
Increasing salt and water intake is one of the first recommendations. Salt helps your body retain fluid, which raises blood volume. Clinicians who treat orthostatic hypotension often suggest a high-salt diet of 8 to 10 grams of sodium chloride per day, sometimes supplemented with salt tablets, because reaching that level through food alone is difficult. This is the opposite of the standard heart-healthy advice to limit sodium, so it only applies to people with confirmed symptomatic hypotension, not to everyone with a low reading.
Drinking more water throughout the day, particularly before meals and before getting out of bed, helps maintain blood volume. Eating smaller, more frequent meals can reduce the postprandial dip by limiting how much blood gets redirected to digestion at once. Cutting back on alcohol helps because it dilates blood vessels and promotes fluid loss.
Physical Techniques That Prevent Fainting
When you feel a dizzy spell coming on, several physical counter-maneuvers can buy your body time to stabilize. These work by squeezing blood out of the large muscles in your legs and abdomen, pushing it back toward your heart and brain.
- Leg crossing with muscle tensing: Cross your legs and tense your leg, abdominal, and buttock muscles simultaneously. You can do this while standing or lying down.
- Squatting: Lowering into a squat compresses the blood vessels in your legs and forces blood upward. Tense your lower body and abdominal muscles during the squat for extra effect, then stand slowly once symptoms pass.
- Arm tensing: Grip your hands together, interlocking fingers, and pull in opposite directions with maximum force. This raises blood pressure temporarily through whole-body muscle activation.
- Isometric handgrip: Clench your fist as hard as you can, with or without an object in your hand. This simple contraction can raise blood pressure enough to prevent a faint.
Beyond these in-the-moment techniques, building habits helps prevent episodes in the first place. Stand up slowly, especially first thing in the morning. Sit on the edge of the bed for 30 seconds before getting to your feet. Avoid standing motionless for long periods. Compression stockings that reach waist height can reduce blood pooling in the legs, which is particularly helpful for people with orthostatic hypotension.
If lifestyle changes aren’t enough, medications that raise blood pressure or increase blood volume are available, but they’re typically reserved for people whose symptoms significantly interfere with daily life despite trying non-drug approaches first.