Low blood pressure is generally defined as a reading below 90/60 mmHg, meaning the top number (systolic) is under 90 or the bottom number (diastolic) is under 60. But a number on a monitor isn’t the only way to tell. Your body gives clear signals when blood pressure drops too low, and learning to recognize them can help you respond before symptoms get worse.
What Low Blood Pressure Feels Like
Some people walk around with naturally low blood pressure and feel perfectly fine. The number only matters when it starts causing symptoms. When blood pressure drops low enough to reduce blood flow to your brain and organs, you’ll typically notice some combination of the following:
- Dizziness or lightheadedness, especially when standing up
- Blurred or fading vision
- Fatigue that feels disproportionate to your activity level
- Trouble concentrating or a foggy, unfocused feeling
- Nausea or an upset stomach
- Fainting
These symptoms often come on gradually. You might notice that you feel “off” for hours before connecting it to blood pressure. Fatigue and difficulty concentrating are easy to blame on poor sleep or stress, so low blood pressure sometimes flies under the radar for a while.
The Standing-Up Test
One of the most recognizable patterns of low blood pressure happens when you stand up from sitting or lying down. The room spins, your vision darkens at the edges, and you might need to grab something for balance. This is called orthostatic hypotension, and it’s defined as a drop of at least 20 points in systolic pressure or 10 points in diastolic pressure within three minutes of standing.
It happens because gravity pulls blood toward your legs when you rise. Normally, your body compensates almost instantly by tightening blood vessels and slightly increasing heart rate. When that reflex is sluggish or overwhelmed, your brain briefly loses adequate blood flow. If you consistently feel dizzy or unsteady when getting up, that’s one of the most reliable clues that your blood pressure is running low. Orthostatic hypotension affects an estimated 7% to 10% of adults with high blood pressure, particularly older adults, which means it can show up even in people already being treated for the opposite problem.
How to Check at Home
A home blood pressure monitor is the most direct way to confirm what you’re feeling. Automated cuff-style monitors that wrap around your upper arm are widely available and reliable when used correctly. Here’s how to get an accurate reading:
- Don’t eat, drink, or exercise for 30 minutes before measuring.
- Empty your bladder first.
- Sit with your back supported for at least five minutes before taking a reading.
- Keep both feet flat on the floor, legs uncrossed.
- Rest your arm on a table so the cuff sits at chest height.
- Place the cuff on bare skin, not over clothing, and make sure it’s snug without being tight.
- Stay still and don’t talk during the reading.
Take at least two readings one to two minutes apart, and do this at the same time each day. A single low reading doesn’t tell you much. What matters is the pattern. If you’re consistently seeing numbers below 90/60 and experiencing symptoms, that’s meaningful information to share with a healthcare provider. Keeping a written log makes this much easier to track over time.
If you suspect orthostatic hypotension specifically, try taking a reading while seated, then standing and taking another reading after one to three minutes. A noticeable drop between the two gives you useful data.
Common Causes of Low Blood Pressure
Dehydration is one of the most frequent and fixable causes. When your body loses more fluid than it takes in, blood volume drops, and pressure follows. This is why low blood pressure symptoms often flare up in hot weather, after intense exercise, or during illness with vomiting or diarrhea.
Medications are another major contributor, and this catches many people off guard. Blood pressure drugs like diuretics (water pills), beta-blockers, and calcium channel blockers can overshoot their target and push pressure too low. But it’s not just heart medications. Antidepressants, including SSRIs, tricyclics, and SNRIs, can lower blood pressure as a side effect. So can anti-anxiety medications like benzodiazepines, certain prostate medications (alpha-blockers), and nitrate drugs used for chest pain. If your symptoms started or worsened after beginning a new medication, that connection is worth investigating.
Other causes include heart conditions that reduce the heart’s pumping ability, thyroid or adrenal gland problems, significant blood loss, severe infection, and prolonged bed rest. Pregnancy commonly lowers blood pressure, especially during the first and second trimesters, as the circulatory system expands rapidly.
When Low Blood Pressure Becomes Dangerous
Mild, occasional dizziness when you stand up too fast is usually more annoying than dangerous. But severely low blood pressure can become a medical emergency when it progresses to shock, a condition where organs aren’t getting enough blood to function.
Signs that low blood pressure has crossed into dangerous territory include confusion or disorientation, cold and clammy skin, rapid and shallow breathing, a weak but fast pulse, and pale or bluish skin tone. These symptoms develop when the body can no longer compensate for the pressure drop. Fainting that comes on without warning, especially if it leads to a fall or injury, also warrants urgent attention.
What Happens During Medical Evaluation
If low blood pressure symptoms are frequent or severe, a doctor will typically start with seated and standing blood pressure measurements in the office to check for orthostatic changes. Blood tests can rule out anemia, thyroid problems, and blood sugar issues.
For people who faint repeatedly without a clear explanation, a tilt table test may be recommended. During this test, you lie flat on a table that slowly tilts you to an almost-upright position while monitors track your blood pressure and heart rate. The goal is to reproduce the conditions that trigger your symptoms in a controlled setting. The tilt shifts blood toward your legs, and doctors watch how your nervous system responds. If your body fails to compensate properly, the test can pinpoint whether the problem is a reflexive drop in blood pressure, a heart rate issue, or both.
Simple Ways to Manage Mild Symptoms
If your blood pressure runs low but isn’t caused by an underlying condition requiring treatment, everyday adjustments can make a noticeable difference. Drinking more water throughout the day helps maintain blood volume. Adding a bit of extra salt to your diet (the opposite of the usual advice for high blood pressure) can raise pressure slightly, though this should be discussed with a provider if you have heart or kidney concerns.
Standing up slowly gives your body time to adjust. If you’ve been lying down, sit on the edge of the bed for 30 seconds before getting to your feet. Compression stockings can help prevent blood from pooling in your legs. Eating smaller, more frequent meals reduces the blood pressure dip that sometimes follows large meals, especially in older adults. Avoiding alcohol also helps, since it dilates blood vessels and can worsen low pressure.
If a medication is the likely cause, your doctor may adjust the dose or timing rather than stopping it entirely. Taking blood pressure drugs at bedtime instead of in the morning, for example, can reduce daytime dizziness in some cases.