Blood pressure below 90/60 mmHg is generally considered low, a condition called hypotension. That means the top number (systolic) is under 90 or the bottom number (diastolic) is under 60. But unlike high blood pressure, which is dangerous at any level above the threshold, 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 measures the force of blood against your artery walls when your heart beats. The bottom number measures that pressure between beats, when your heart is resting. A reading of 120/80 is considered normal, and anything below 90/60 falls into the low range.
Here’s the important distinction: many people walk around with blood pressure in the 80s or even 70s systolic and feel perfectly fine. If you’re young, physically active, and have no symptoms, a low reading on its own isn’t a diagnosis. It’s actually associated with better long-term cardiovascular health. Low blood pressure only becomes a clinical concern when it’s causing noticeable problems or dropping suddenly.
Symptoms That Signal a Problem
When blood pressure drops low enough that your brain and organs aren’t getting adequate blood flow, you’ll typically notice it. Common symptoms include dizziness or lightheadedness, blurred or fading vision, fatigue, trouble concentrating, nausea, and fainting. These tend to be worse when you stand up quickly, exercise in the heat, or skip meals.
Severely low blood pressure can lead to shock, which is a medical emergency. Signs of shock look different from everyday lightheadedness: confusion (particularly in older adults), cold and clammy skin, pale or ashen skin tone, rapid shallow breathing, and a weak, fast pulse. This level of blood pressure drop usually results from something acute like severe dehydration, blood loss, an allergic reaction, or a serious infection.
Types of Low Blood Pressure
Orthostatic Hypotension
This is the most common type and happens when you stand up from sitting or lying down. It’s diagnosed when your systolic pressure drops by 20 mmHg or more, or your diastolic drops by 10 mmHg or more, within three minutes of standing. If you already have high blood pressure while lying down, the threshold is a 30 mmHg systolic drop. That familiar head rush when you get out of bed too fast is a mild version of this. It becomes a real concern when it causes repeated falls or fainting episodes, especially in older adults.
Postprandial Hypotension
Some people experience a significant blood pressure drop after eating. The top number typically falls about 20 mmHg, usually within 30 to 60 minutes of a meal, though the effect can last up to two hours. This happens because your body diverts blood to your digestive system after you eat. It’s most common in older adults and people with conditions affecting the nervous system.
Low Blood Pressure During Pregnancy
Blood pressure naturally falls during the first trimester and continues to dip in the second trimester before gradually returning to pre-pregnancy levels around the time of delivery. This is normal and expected. A slight drop during the first half of pregnancy doesn’t typically increase risk for you or the baby. Normal blood pressure in pregnancy is anything with a top number below 140 and a bottom number below 90, so the range considered acceptable is wider than you might expect.
Common Causes
Dehydration is one of the most frequent and easily fixable causes. When your blood volume drops because you haven’t been drinking enough water, or because of vomiting, diarrhea, or heavy sweating, there’s simply less fluid for your heart to pump, and pressure falls.
Medications are another major contributor. Blood pressure drugs, water pills, certain antidepressants, and medications for prostate conditions can all lower blood pressure as either their intended effect or a side effect. If you’ve recently started or adjusted a medication and notice dizziness or lightheadedness, that’s worth bringing up at your next appointment.
Heart conditions that affect how well your heart pumps, hormonal problems like thyroid disorders or adrenal insufficiency, and nutritional deficiencies (particularly low levels of B12, folate, or iron) can all contribute to chronically low blood pressure. Prolonged bed rest also leads to lower readings because the cardiovascular system adapts to the horizontal position and struggles to compensate when you finally stand up.
Managing Low Blood Pressure
If your blood pressure runs low but you have no symptoms, treatment is rarely needed. The focus is on lifestyle adjustments rather than medication for most people with mild symptoms.
Drinking more water is the simplest intervention. Increasing fluid intake raises your blood volume, which directly supports blood pressure. This is especially important in hot weather, during exercise, and if you’re recovering from illness.
Adding more salt to your diet is sometimes recommended, which is the opposite of what most blood pressure advice says. Because sodium raises blood pressure, a modest increase can help people with hypotension. This needs to be done carefully, though, because too much sodium can strain the heart over time, particularly in older adults. It’s a strategy that works best when guided by a healthcare provider who can weigh the tradeoffs for your specific situation.
For orthostatic hypotension, practical strategies make a real difference. Standing up slowly, sitting on the edge of the bed for a minute before getting up in the morning, wearing compression stockings to prevent blood from pooling in your legs, and eating smaller, more frequent meals (to reduce postprandial drops) are all effective approaches. Crossing your legs while standing or clenching your thigh muscles can also temporarily boost blood pressure when you feel a dizzy spell coming on.
If these lifestyle changes aren’t enough and symptoms are significantly affecting your daily life, medications that help your body retain fluid or constrict blood vessels are available. But most people with low blood pressure manage well without them.