Low blood pressure, called hypotension, is any reading below 90/60 mmHg. That means either the top number (systolic) is under 90, or the bottom number (diastolic) is under 60, or both. Unlike high blood pressure, which is almost always a concern, low blood pressure is only a problem if it causes symptoms or signals something else going on in your body.
What the Numbers Mean
A blood pressure reading has two numbers. The top number (systolic) measures the force of blood against artery walls when your heart beats. The bottom number (diastolic) measures that pressure between beats, when the heart is resting. A normal reading falls below 120/80 mmHg. Once it drops below 90/60 mmHg, it’s classified as low.
There’s no single “dangerously low” cutoff that applies to everyone. Some people walk around with a systolic pressure in the 80s and feel perfectly fine. What matters more than the number itself is whether you’re experiencing symptoms like dizziness, lightheadedness, blurred vision, or fatigue. If your blood pressure is low and you feel normal, it’s generally not harmful and doesn’t need treatment.
When Low Blood Pressure Is Normal
People who are very physically active, especially younger adults and endurance athletes, often have resting blood pressure well below 90/60 mmHg without any ill effects. Their hearts are efficient enough to pump adequate blood at lower pressures. This is a sign of cardiovascular fitness, not a medical problem.
Genetics play a role too. Some people simply run on the lower end their entire lives. If your blood pressure has always been on the low side and you don’t have symptoms, there’s nothing to fix.
Types of Low Blood Pressure
Orthostatic (Postural) Hypotension
This is the dizzy, head-rush feeling when you stand up too quickly. It’s diagnosed when your systolic pressure drops by 20 mmHg or more, or your diastolic drops by 10 mmHg or more, within two to five minutes of standing. Common symptoms include lightheadedness, blurred vision, neck and shoulder pain, and in some cases chest tightness or shortness of breath. It’s especially common in older adults and people on certain medications.
A drop of 30 mmHg or more in systolic pressure on standing, particularly if it’s severe enough to interfere with daily activities, may warrant evaluation by a specialist.
Postprandial Hypotension
Some people experience a significant blood pressure drop after eating. With postprandial hypotension, the systolic number falls about 20 mmHg or more after a meal, typically within 30 to 60 minutes of eating, though it can happen up to two hours later. Blood gets redirected to the digestive system, and in some people the body doesn’t compensate well enough to keep overall pressure stable. This is most common in older adults.
Common Causes
Dehydration is one of the most frequent triggers. When your body doesn’t have enough fluid, blood volume drops, and pressure falls with it. Prolonged bed rest, pregnancy (especially in the first and second trimesters), and large blood loss from injury or surgery can all cause low blood pressure.
Several categories of medications are well-known culprits. Blood pressure drugs like ACE inhibitors, calcium-channel blockers, and beta-blockers can sometimes push pressure too low, particularly when doses are adjusted. Water pills (diuretics), certain antidepressants, and medications used for prostate conditions (alpha-blockers) also commonly contribute. If you’ve recently started or changed a medication and notice dizziness or lightheadedness, that connection is worth exploring with whoever prescribed it.
Underlying conditions can also be responsible. Heart problems that reduce pumping efficiency, hormonal imbalances like adrenal insufficiency or thyroid disorders, and nervous system conditions that affect how the body regulates blood pressure can all lead to chronic hypotension.
Symptoms to Pay Attention To
Mild, occasional dizziness when standing isn’t unusual and doesn’t always mean something is wrong. But a consistent pattern of symptoms suggests your body isn’t compensating well. The key signs include:
- Lightheadedness or dizziness, especially when changing positions
- Blurred or fading vision
- Fatigue or difficulty concentrating
- Nausea
- Fainting or near-fainting
When blood pressure drops severely, such as during significant blood loss or a severe allergic reaction, it can progress to shock. At that point, systolic pressure typically falls below 90 mmHg with a very narrow gap between the two numbers (less than 20 mmHg difference). Symptoms of shock include cold, clammy skin, rapid shallow breathing, confusion, and a weak, fast pulse. This is a medical emergency.
Managing Low Blood Pressure Day to Day
The goal of treating low blood pressure isn’t to hit a specific number. It’s to reduce symptoms and keep them from limiting your life. For many people, simple habits make a meaningful difference.
Increasing fluid intake is a first step. A general recommendation is 60 to 100 ounces of fluid per day, which works out to roughly 7 to 12 cups. Alongside that, increasing salt intake to about 3 to 5 grams daily helps the body retain fluid and maintain blood volume. This is the opposite of the advice given for high blood pressure, so it only applies if your pressure genuinely runs low.
Other practical strategies include standing up slowly (pause at the edge of the bed before getting up), eating smaller, more frequent meals to reduce postprandial drops, wearing compression stockings to prevent blood from pooling in your legs, and avoiding alcohol, which dilates blood vessels and lowers pressure further. Crossing your legs or tensing your thigh muscles before standing can also help push blood back toward your heart during position changes.
If lifestyle changes aren’t enough and symptoms are significantly affecting your quality of life, your doctor may adjust medications that could be contributing or, in some cases, add a medication specifically to raise blood pressure.