A blood pressure reading of 90/60 mmHg or lower is considered low blood pressure, clinically called hypotension. That means either the top number (systolic) is below 90, the bottom number (diastolic) is below 60, or both. For many people, naturally low blood pressure causes no symptoms and is simply how their body works. It only becomes a medical concern when it drops low enough to reduce blood flow to your organs, causing noticeable symptoms like dizziness, fainting, or fatigue.
What the Numbers Mean
Blood pressure is recorded as 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 your heart is resting. A normal reading falls below 120/80 mmHg, while an optimal reading sits around 110/70 for most adults.
There’s no single “too low” number that applies to everyone. Some people walk around with a systolic reading in the 80s and feel perfectly fine. Athletes and people who exercise regularly often have resting blood pressure well below 120/80 because their cardiovascular system is efficient. The reading itself matters less than whether it’s causing symptoms. A blood pressure of 85/55 in someone who feels normal is very different from that same reading in someone who feels lightheaded and confused.
Symptoms That Signal a Problem
When blood pressure drops low enough to limit blood flow to the brain and other organs, you’ll typically notice it. The most common signs include dizziness or lightheadedness, blurred vision, nausea, fatigue, and difficulty concentrating. Some people feel cold or clammy, especially in the hands and feet, because the body redirects blood flow toward vital organs.
Fainting is one of the more dramatic symptoms and happens when the brain temporarily doesn’t get enough blood. If low blood pressure becomes severe, it can progress to shock, which is a medical emergency. Signs of shock include rapid, shallow breathing, a weak and fast pulse, pale or bluish skin, and confusion. This level of blood pressure drop usually results from something acute like a serious infection, major blood loss, or a severe allergic reaction.
Types of Low Blood Pressure
Not all low blood pressure behaves the same way. The type you have depends on when and why it drops.
Orthostatic hypotension is a sudden drop when you stand up from sitting or lying down. It’s diagnosed when your systolic pressure falls by 20 mmHg or more, or your diastolic pressure falls by 10 mmHg or more, within three minutes of standing. You’ve probably experienced a mild version of this: that brief head rush when you get out of bed too fast. In older adults or people on certain medications, it can be severe enough to cause falls.
Postprandial hypotension is a drop that happens after eating. Your systolic pressure may fall by about 20 mmHg within 30 to 60 minutes of a meal, though it can occur up to two hours afterward. This happens because digestion diverts a large volume of blood to the gut. It’s most common in older adults and people with conditions that affect the nervous system’s ability to regulate blood flow.
Neurally mediated hypotension occurs after standing for long periods. It’s caused by a miscommunication between the brain and heart, and it’s more common in children and young adults.
Common Causes
Dehydration is one of the most frequent and easily fixable causes. When your body loses more fluid than it takes in, blood volume decreases, and pressure drops. This can happen from not drinking enough water, sweating heavily, vomiting, or diarrhea. Even mild dehydration can lower your readings noticeably.
Heart conditions that reduce the heart’s pumping ability, like heart valve problems or heart failure, can lead to chronically low blood pressure. Endocrine disorders, particularly those affecting the adrenal glands or thyroid, also play a role because hormones help regulate blood pressure. Severe infections that enter the bloodstream can cause a dangerous form of low blood pressure by triggering widespread inflammation that makes blood vessels dilate.
Pregnancy commonly lowers blood pressure. Blood vessels expand and hormonal shifts alter circulation to support the growing baby. Blood pressure typically falls during the first trimester, continues dropping through the second trimester, then gradually rises back toward pre-pregnancy levels by delivery. This is normal, though it can cause dizziness, particularly when standing quickly.
Medications That Lower Blood Pressure
Several types of medication can cause low blood pressure as a side effect. Blood pressure medications themselves are the most obvious culprits, including diuretics (water pills), alpha blockers, and beta blockers. If your dose is too high or you’re taking multiple blood pressure drugs, your readings may drop further than intended.
Other medications that can lower blood pressure include certain antidepressants (particularly the older tricyclic class), drugs used for Parkinson’s disease, and erectile dysfunction medications. The risk increases when erectile dysfunction drugs are combined with heart medications like nitroglycerin, which can cause a steep and dangerous pressure drop. If you notice new dizziness or lightheadedness after starting any medication, that’s worth mentioning to whoever prescribed it.
What to Do About Low Readings
If your blood pressure consistently reads below 90/60 but you feel fine, you likely don’t need to do anything. Some people simply run low, and that’s their baseline.
If you’re getting symptoms, a few practical steps can help. Drinking more fluids, particularly water and beverages with electrolytes, increases blood volume and can raise pressure. Adding a bit more salt to your diet works for some people, though this should be balanced against other health considerations. Eating smaller, more frequent meals can reduce postprandial drops by limiting how much blood gets diverted to digestion at once.
For orthostatic hypotension, get up slowly. Sit on the edge of the bed for a moment before standing. Crossing your legs or squeezing your thigh muscles before standing can also help push blood back toward the upper body. Compression stockings reduce blood pooling in the legs and are particularly helpful for people who stand for long periods.
If your symptoms are frequent, severe, or include fainting, that warrants medical evaluation. A sustained drop in blood pressure can sometimes point to an underlying condition that needs treatment, whether it’s a heart issue, an endocrine problem, or a medication that needs adjusting. Tracking your readings at home with dates and times, along with notes about what you were doing when symptoms occurred, gives your provider useful information to work with.