Blood pressure below 90/60 mmHg is generally considered low. That means a systolic reading (the top number) under 90 or a diastolic reading (the bottom number) under 60. But unlike high blood pressure, where the numbers alone signal risk, low blood pressure is only a medical concern when it causes symptoms or drops suddenly.
What the Numbers Mean
A normal blood pressure reading falls around 120/80 mmHg. The top number measures the force of blood against artery walls when the heart beats, and the bottom number measures that force between beats. When either number dips below the 90/60 threshold, the reading is classified as hypotension.
Some people walk around with a resting blood pressure of 85/55 and feel perfectly fine. Athletes and people who exercise regularly often have naturally lower blood pressure because their hearts pump more efficiently. In these cases, a low reading is actually a sign of good cardiovascular health, not a problem. The number on the cuff only becomes meaningful when your body starts telling you something is wrong.
Symptoms That Signal a Problem
When blood pressure drops low enough that your organs aren’t getting adequate blood flow, you’ll typically notice it. The most common signs include dizziness or lightheadedness, blurred vision, nausea, fatigue, and difficulty concentrating. Some people feel faint or actually pass out, which is one of the more serious consequences because of the risk of falling and injuring yourself.
In severe cases, blood pressure can fall dangerously low. A systolic reading below 110 mmHg is associated with increased mortality in trauma patients, and when pressure drops far enough that organs like the brain, kidneys, and heart aren’t getting enough oxygen, the body goes into shock. Signs of shock include cold and clammy skin, rapid shallow breathing, a weak and fast pulse, and confusion. This is a medical emergency.
Common Causes of Low Blood Pressure
Dehydration is one of the most frequent triggers. When the body loses more fluid than it takes in, blood volume decreases and pressure drops. Fever, vomiting, severe diarrhea, heavy sweating during exercise, and overuse of diuretic medications can all push you into dehydration quickly enough to lower your readings.
Nutritional deficiencies play a role too. Low levels of vitamin B-12, folate, and iron can prevent your body from producing enough red blood cells, a condition called anemia. With fewer red blood cells carrying oxygen through the bloodstream, blood pressure can fall. Hormone-related conditions, including thyroid disorders, adrenal insufficiency (Addison’s disease), and diabetes, can also disrupt the body’s ability to regulate pressure. Low blood sugar alone can cause a temporary drop.
Medications are another common culprit. Blood pressure drugs, certain antidepressants, drugs for Parkinson’s disease, and erectile dysfunction medications can all lower pressure as a primary effect or side effect. If you’ve recently started a new medication and notice dizziness when standing or persistent fatigue, your blood pressure may be running too low.
Orthostatic Hypotension: Drops When You Stand
One of the most recognizable forms of low blood pressure happens when you go from sitting or lying down to standing up. This is called orthostatic hypotension, and 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. That sudden shift is what causes the head rush, wobbly feeling, or momentary blackout some people experience when they get out of bed too quickly.
Gravity pulls blood toward your legs when you stand, and your body normally compensates by tightening blood vessels and increasing heart rate. When that response is too slow or too weak, pressure falls temporarily. Older adults, people on blood pressure medications, and those who are dehydrated are most prone to it.
Drops After Eating
Postprandial hypotension is a large drop in blood pressure that occurs within about 30 to 60 minutes of eating, though it can happen up to two hours after a meal. After you eat, your body directs extra blood flow to the digestive system, and in some people, the cardiovascular system doesn’t compensate well enough to keep pressure stable everywhere else.
This type of low blood pressure is especially common in older adults. Research shows that roughly 40% of people between ages 65 and 86 experience it. The risk is higher if you also have high blood pressure, diabetes, Parkinson’s disease, heart failure, or kidney disease. Eating smaller, more frequent meals and limiting high-carbohydrate foods can help reduce the drop.
Low Blood Pressure During Pregnancy
Blood pressure commonly falls during the first trimester and continues to decline through the second trimester. This happens because the circulatory system expands rapidly to supply the growing baby, and blood vessels relax in response to hormonal changes. Pressure typically rises back toward pre-pregnancy levels by the time of delivery. Mild dizziness and fatigue during early pregnancy are often related to this natural dip, and staying well-hydrated helps.
Managing Chronic Low Blood Pressure
If your blood pressure runs low and you experience symptoms regularly, a few straightforward adjustments can make a real difference. Drinking more water increases blood volume and helps prevent dehydration. Adding extra salt to your diet can raise blood pressure, since sodium causes the body to retain fluid. This is the opposite of the advice given to people with high blood pressure, and it’s worth noting that too much sodium can strain the heart over time, particularly in older adults.
Other practical strategies include standing up slowly, avoiding prolonged standing, wearing compression stockings to prevent blood from pooling in the legs, and eating smaller meals to reduce postprandial drops. Crossing your legs while sitting and tensing your thigh muscles before standing can also help push blood back toward your upper body. If a medication is the cause, adjusting the dose or timing often resolves the issue.