Blood pressure is generally considered too low when the top number (systolic) drops below 90 mmHg or the bottom number (diastolic) falls below 60 mmHg. But that threshold is a rough guide, not a hard rule. Some people walk around with naturally low readings their entire lives and feel perfectly fine. What actually makes low blood pressure a problem is whether it’s causing symptoms or signaling something else going on in your body.
The Numbers That Matter
A normal blood pressure reading falls around 120/80 mmHg. The clinical definition of hypotension (low blood pressure) starts at 90/60 mmHg, but context matters more than the number itself. A fit 25-year-old with a resting blood pressure of 85/55 who feels great has no problem. An 80-year-old whose pressure suddenly drops to 95/58 and feels dizzy has a very different situation.
The more useful way to think about it: low blood pressure is “too low” when your brain and organs aren’t getting enough blood flow to work properly. That shows up as symptoms you can feel.
Symptoms of Blood Pressure That’s Too Low
The earliest and most common sign is lightheadedness or dizziness, especially when you stand up. Your brain sits at the top of your body and is the first organ to notice when blood flow drops. Beyond dizziness, you might experience blurred vision, nausea, fatigue, or trouble concentrating. Some people describe a general feeling of being “off” or foggy-headed.
More concerning symptoms include fainting, cold and clammy skin, rapid shallow breathing, and confusion. These suggest your body is struggling to compensate and your organs are being affected. Fainting is particularly risky because the fall itself can cause serious injury, especially in older adults.
At the extreme end, dangerously low blood pressure can lead to shock, where organs start to shut down. Signs of shock include a weak, rapid pulse, pale skin, and confusion that progresses to unresponsiveness. This is an emergency.
What Causes Blood Pressure to Drop
The list of causes ranges from completely harmless to life-threatening, which is part of why this question doesn’t have a simple numeric answer.
Dehydration is one of the most common culprits. When your blood volume drops because you haven’t been drinking enough fluids, or you’ve been sweating, vomiting, or having diarrhea, your pressure can fall noticeably. Nutritional deficiencies play a role too. Low levels of vitamin B-12, folate, or iron can prevent your body from making enough red blood cells (a condition called anemia), which lowers blood pressure.
Heart conditions are another major category. A heart attack, heart failure, heart valve problems, or an abnormally slow heart rate can all reduce the amount of blood your heart pumps out, dropping your pressure. Hormone-related conditions like Addison’s disease (where certain glands don’t produce enough hormones), low blood sugar, and diabetes can also be involved. Pregnancy commonly lowers blood pressure, particularly in the first 24 weeks, because the circulatory system expands rapidly.
Severe infections that spread to the bloodstream and life-threatening allergic reactions both cause blood pressure to plummet quickly. These are emergencies where the low pressure itself becomes the danger.
Medications That Lower Blood Pressure
If you’re taking medication and noticing symptoms, that’s worth paying attention to. Blood pressure medications are the most obvious offenders, including water pills (diuretics), beta blockers, and alpha blockers. But they’re far from the only ones. Medications for heart failure, depression, erectile dysfunction, and neurological conditions can all lower blood pressure as a side effect. Alcohol and recreational drugs can do the same.
An important finding from the 2025 AHA/ACC blood pressure guidelines: intensive blood pressure treatment using standard first-line medications does not appear to increase the risk of harmful low-pressure episodes, even in older adults. So if you’re on blood pressure medication and feeling fine, the treatment is likely appropriate. If you’re feeling dizzy or faint, the dose or combination may need adjusting.
Types of Low Blood Pressure
Not all hypotension works the same way, and knowing the type helps explain what’s happening.
Orthostatic hypotension is a blood pressure drop that happens when you stand up. It’s diagnosed when your top number falls by 20 mmHg or more, or your bottom number falls by 10 mmHg or more, within two to five minutes of standing. This affects an estimated 7% to 10% of adults with high blood pressure, and it’s especially common in older adults. If you feel lightheaded every time you get out of bed or stand up from a chair, this is likely what’s happening.
Postprandial hypotension is a drop that occurs up to two hours after eating a meal, defined as a top number drop of about 20 mmHg. Your digestive system draws extra blood flow after a meal, and in some people the body can’t compensate quickly enough. This is surprisingly common in older adults: studies show about 40% of people between ages 65 and 86 experience it. Risk factors include high blood pressure, Parkinson’s disease, diabetes, and heart failure.
Neurally mediated hypotension is a pressure drop triggered by standing for long periods. It mostly affects young adults and children and appears to stem from miscommunication between the heart and the brain.
What You Can Do About It
If your blood pressure runs low and it’s bothering you, several straightforward strategies can help. Drinking more water increases blood volume and is often the simplest fix. Adding more salt to your diet can raise blood pressure, which is one of those rare situations where the usual advice gets flipped on its head. That said, increasing salt intake isn’t appropriate for everyone, particularly older adults with heart failure, so it’s worth discussing with a healthcare provider first.
Compression stockings, the kind often used for varicose veins, help push blood from your legs back toward your heart and can reduce symptoms of orthostatic hypotension. Standing up slowly, especially first thing in the morning, gives your cardiovascular system time to adjust. If postprandial hypotension is the issue, eating smaller, more frequent meals and resting after eating can help.
For orthostatic hypotension specifically, avoiding prolonged standing, crossing your legs while standing, and tensing your leg muscles before getting up can all make a difference. Avoiding alcohol helps too, since it dilates blood vessels and lowers pressure further.
When Low Blood Pressure Is Actually a Good Thing
It’s worth remembering that for many people, naturally low blood pressure is a sign of good cardiovascular health, not a problem. Athletes and people who exercise regularly often have resting blood pressures well below 120/80 because their hearts pump more efficiently. If your pressure is on the low side and you feel fine, with no dizziness, no fatigue, no fainting, there’s typically nothing to worry about. The number only becomes “too low” when your body tells you it is.