A blood pressure reading below 90/60 mmHg is considered low. That means either the top number (systolic) falls under 90, the bottom number (diastolic) falls under 60, or both. For many people, low blood pressure causes no problems at all. It only becomes a medical concern when it triggers symptoms or drops suddenly.
What the Numbers Mean
A blood pressure reading has two numbers. The top number (systolic) measures the pressure in your arteries when your heart beats. The bottom number (diastolic) measures the pressure between beats, when your heart is resting. Normal blood pressure is below 120/80 mmHg. Once either number dips below the 90/60 threshold, the reading is classified as low.
There’s no universally “perfect” blood pressure. Some people naturally run low, with readings in the 80s/50s range, and feel completely fine. This is especially common in people who exercise regularly. A stronger heart pumps blood more efficiently with each beat, which means less force against artery walls at rest. Blood vessels also stay more elastic in active people, allowing blood to flow with less resistance. So a reading that looks low on paper can actually reflect excellent cardiovascular fitness.
When Low Blood Pressure Causes Symptoms
Low blood pressure becomes a problem when your brain and organs aren’t getting enough blood flow. The most common signs include dizziness, lightheadedness, blurred vision, nausea, fatigue, and difficulty concentrating. Some people feel like they’re about to faint, particularly when standing up quickly or after a long period of standing still. In more severe cases, you may actually lose consciousness.
If your blood pressure drops extremely low, the situation can become dangerous. Signs of a serious drop include cold and clammy skin, pale complexion, rapid and weak pulse, shallow breathing, confusion, and little to no urine output. These are signs of shock, which means your body’s organs are being starved of blood, and it requires emergency treatment.
Orthostatic Hypotension: The Standing-Up Drop
One of the most common forms of low blood pressure happens when you stand up from sitting or lying down. This is called orthostatic hypotension, and it’s diagnosed when your systolic pressure drops by 20 mmHg or more, or your diastolic pressure drops by 10 mmHg or more, upon standing. You might also feel dizzy or lightheaded even if the numbers don’t hit those exact thresholds.
Gravity pulls blood toward your legs when you stand. Your body normally compensates by tightening blood vessels and slightly increasing heart rate. When that reflex is sluggish, whether from dehydration, medication, or aging, blood pressure temporarily drops and you feel unsteady. This is especially common in older adults and is a significant risk factor for falls.
Postprandial Hypotension: After Eating
Some people experience a noticeable blood pressure drop after meals. With postprandial hypotension, the top blood pressure number typically falls about 20 mmHg after eating, usually within 30 to 60 minutes. This happens because digestion requires extra blood flow to the stomach and intestines. In some people, the body doesn’t compensate well enough, and blood pressure sags. It’s most common in older adults and people with conditions affecting the nervous system.
Common Causes of Low Blood Pressure
Dehydration is one of the simplest and most frequent 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, from prolonged heat exposure, from vomiting or diarrhea, or from intense exercise without adequate fluids.
Blood pressure medications, including diuretics and other drugs used to manage high blood pressure, can sometimes push readings too low. This is a well-recognized side effect, particularly in older adults. Other medications for conditions like depression, Parkinson’s disease, and enlarged prostate can also lower blood pressure as a side effect.
Heart conditions that reduce the heart’s pumping ability, severe infections that spread to the bloodstream, and significant blood loss all cause blood pressure to fall. Endocrine problems, including underactive thyroid and adrenal insufficiency (where the adrenal glands don’t produce enough hormones), can lead to chronically low readings. Severe allergic reactions cause a sudden, dramatic drop in blood pressure that requires immediate treatment.
Low Blood Pressure Without Symptoms
If your blood pressure consistently reads below 90/60 but you feel perfectly normal, there’s generally nothing to worry about. Some people, particularly younger women and physically active individuals, live their entire lives with blood pressure in this range. It only warrants attention when it causes symptoms, when it represents a change from your usual readings, or when it drops suddenly. Keeping track of your typical range helps you and your doctor spot meaningful changes over time.