Blood pressure below 90/60 mmHg is the standard medical threshold for low blood pressure, also called hypotension. But that number alone doesn’t tell the whole story. Some people walk around at 85/55 their entire lives and feel perfectly fine, while others experience dizziness and fainting at 95/65. What matters most is whether your body can still deliver enough blood to your brain and organs at your particular reading.
The Numbers That Define Low Blood Pressure
Normal blood pressure is anything below 120/80 mmHg. The range between 90/60 and 120/80 is where most healthy adults sit comfortably. Once you drop below 90/60, you’ve crossed into what clinicians call hypotension.
But context changes everything. A reading of 88/58 in a fit 25-year-old runner is often a sign of excellent cardiovascular health, not a problem. Physically active and younger people commonly have resting blood pressure below the 90/60 line with no symptoms at all. The threshold only becomes meaningful when your body starts struggling to compensate for the lower pressure, which shows up as symptoms like lightheadedness, blurred vision, or fatigue.
Most healthcare professionals treat low blood pressure as a concern only when it causes symptoms. If your readings are consistently below 90/60 and you feel fine, you likely don’t need treatment.
When a Sudden Drop Matters More Than the Number
A blood pressure reading that’s low on its own is one thing. A sudden fall from your normal baseline is another, and it can be more dangerous than a chronically low reading. A drop of just 20 mmHg in your top number, say from 110 to 90, can be enough to make you dizzy or cause you to faint. That’s because your brain needs a steady supply of blood, and abrupt changes don’t give your body time to adjust.
This is why two specific types of blood pressure drops get their own names:
- Orthostatic hypotension: Your systolic (top) number drops by 20 mmHg or more, or your diastolic (bottom) number drops by 10 mmHg or more, within two to five minutes of standing up. It’s normal for blood pressure to dip briefly when you change positions, but if it stays low for longer than about three minutes, that’s a clinical concern.
- Postprandial hypotension: Your systolic pressure drops about 20 mmHg within 30 to 60 minutes after eating. This happens because your body diverts blood to your digestive system and can’t fully compensate. It’s most common in older adults.
What Low Blood Pressure Feels Like
When blood pressure drops low enough that your organs aren’t getting adequate blood flow, your body sends clear signals. The most common symptoms are dizziness or lightheadedness, especially when standing up. You might also notice blurred vision, nausea, fatigue, or difficulty concentrating. Some people feel generally “off” without being able to pinpoint exactly what’s wrong.
These symptoms tend to come and go. They’re often worse in the morning, after meals, after standing for a long time, or in hot weather, all situations where blood pressure naturally dips a bit lower.
What Causes Blood Pressure to Run Low
Dehydration is one of the most common and easily fixable causes. When your blood volume drops, even mildly, there’s less fluid to push through your vessels, and pressure falls. This is why low blood pressure often worsens in summer heat or after exercise without adequate fluid replacement.
Several categories of medication can lower blood pressure as a side effect, including drugs prescribed for high blood pressure (when the dose overshoots the target), heart medications, certain antidepressants, and drugs used to treat erectile dysfunction or Parkinson’s disease. If your readings dropped after starting a new medication, that connection is worth exploring with your prescriber.
Pregnancy reliably lowers blood pressure. It steadily decreases through the first half of pregnancy, reaching its lowest point around mid-gestation, then gradually climbs back to early-pregnancy levels by delivery. This is a normal physiological shift, though it can cause dizziness that catches some people off guard.
Heart conditions that reduce the heart’s pumping efficiency, hormonal disorders like adrenal insufficiency or thyroid problems, and significant blood loss can all push blood pressure dangerously low. Severe infections that spread to the bloodstream can cause a rapid, life-threatening drop.
The Risks for Older Adults
Low blood pressure carries particular risks as you age. Research on older adults being treated for high blood pressure found that episodes where systolic pressure dipped below 100 mmHg independently predicted a higher risk of falls, regardless of age, sex, or physical fitness level. Interestingly, the more commonly used cutoff of 90 mmHg didn’t predict falls as reliably. This suggests that for older adults, readings under 100 systolic deserve attention, even if they’re technically above the standard 90/60 threshold.
Symptomatic orthostatic hypotension, the kind where you feel dizzy every time you stand, was also independently linked to fall risk in this population. Falls in older adults can lead to fractures, head injuries, and a cascade of complications, so what might be a harmless low reading in a younger person becomes a genuine safety concern.
When Low Blood Pressure Becomes an Emergency
Extreme drops in blood pressure can lead to shock, a condition where your organs begin to shut down from lack of blood flow. Signs of shock include confusion (especially in older people), cold and clammy skin, rapid shallow breathing, a weak and fast pulse, pale skin, and little or no urine output. This is a medical emergency that requires immediate help.
Shock can result from severe blood loss, serious infections, severe allergic reactions, or heart failure. Losing more than 15 to 20 percent of your blood volume can trigger it. The key difference between everyday low blood pressure and shock is the speed and severity of the drop, combined with signs that your organs are failing to cope.
Managing Chronically Low Blood Pressure
If your blood pressure runs low and causes symptoms, a few practical strategies can help. Increasing your salt intake is one of the most effective. For people with orthostatic hypotension, medical guidelines recommend significantly more sodium than the general population typically consumes, often in the range of 2,400 to 4,000 mg of sodium per day, and sometimes higher. For reference, the standard dietary recommendation for most adults is under 2,300 mg. One study found that adding about 2,400 mg of sodium daily for two months improved both standing tolerance and blood flow regulation in people who were prone to fainting.
Staying well hydrated matters just as much. Drinking water before standing up, eating smaller and more frequent meals (to reduce postprandial drops), wearing compression stockings, and avoiding prolonged standing can all reduce symptoms. Rising slowly from sitting or lying positions gives your circulatory system time to adjust and prevents the sudden drops that cause the worst symptoms.
If these lifestyle changes aren’t enough, there are medications that can raise blood pressure, but the approach depends on what’s causing the problem. Treating the underlying condition, whether that’s adjusting another medication’s dose, addressing dehydration, or managing a hormonal imbalance, is almost always the first step.