Low blood pressure, called hypotension, is generally a reading below 90/60 mmHg. The first number (systolic) measures pressure when your heart beats, and the second (diastolic) measures pressure between beats. Unlike high blood pressure, low blood pressure isn’t defined by a single hard cutoff. Some people walk around at 85/55 their entire lives and feel perfectly fine. It only becomes a medical concern when it causes symptoms or drops suddenly.
How Low Blood Pressure Feels
The core issue with low blood pressure is that your brain and organs aren’t getting enough blood flow. That produces a recognizable cluster of symptoms: dizziness or lightheadedness, blurred or fading vision, fatigue, trouble concentrating, nausea, and fainting. These tend to come on when you stand up quickly, haven’t eaten, or are dehydrated. Many people describe it as a “head rush” that doesn’t fully clear.
When blood pressure drops severely, it can lead to shock, which is a medical emergency. Signs of shock include confusion (particularly in older adults), cold and clammy skin, pale skin, rapid shallow breathing, and a weak, fast pulse. This level of blood pressure drop typically results from a serious trigger like an infection, allergic reaction, or significant blood loss.
Types of Low Blood Pressure
Orthostatic (Postural) Hypotension
This is the most common type people notice. Your blood pressure drops when you go from sitting or lying down to standing. It’s diagnosed when your systolic pressure falls by 20 mmHg or more, or your diastolic pressure falls by 10 mmHg or more, within two to five minutes of standing up. Normally, your body compensates for gravity by tightening blood vessels in your legs and slightly increasing your heart rate. When that reflex is sluggish, blood pools in your lower body and your brain briefly loses adequate flow. Dehydration, prolonged bed rest, pregnancy, and certain medications all make this more likely.
Postprandial Hypotension
Blood pressure can also drop after eating. Your digestive system demands a significant increase in blood flow after a meal, and your body is supposed to compensate by speeding up your heart rate and constricting blood vessels elsewhere. When that compensation fails, pressure drops. This type is surprisingly common in older adults: research shows about 40% of people between ages 65 and 86 experience it. You’re at higher risk if you have high blood pressure (paradoxically), diabetes, Parkinson’s disease, heart failure, or kidney disease.
Neurally Mediated Hypotension
This type strikes after standing for long periods. It’s caused by a miscommunication between the heart and brain. Your brain incorrectly signals your heart to slow down when it should be speeding up, causing a sudden drop. It’s more common in younger people and children, and often shows up as fainting episodes during prolonged standing in hot environments.
Common Causes
Low blood pressure isn’t always a sign of a problem. Athletes and very fit people often have naturally low resting blood pressure because their cardiovascular system is efficient. During the first and second trimesters of pregnancy, blood pressure commonly dips as the circulatory system expands rapidly, then returns to pre-pregnancy levels in the third trimester.
When low blood pressure is new or symptomatic, the most frequent culprits include:
- Dehydration. Even mild dehydration reduces blood volume enough to lower pressure noticeably, especially in warm weather or after exercise.
- Medications. Blood pressure drugs, water pills (diuretics), antidepressants, and medications for erectile dysfunction or Parkinson’s disease can all lower pressure as a side effect. Sometimes two medications interact to produce a bigger drop than either would alone.
- Heart conditions. Valve problems, heart failure, and very slow heart rates reduce the amount of blood your heart pumps with each beat.
- Endocrine problems. Conditions affecting the adrenal glands (like Addison’s disease), thyroid disorders, and low blood sugar can all trigger hypotension.
- Blood loss. Whether from an injury or internal bleeding, losing blood directly reduces the volume available to maintain pressure.
- Severe infection. When an infection enters the bloodstream, it can cause a dangerous drop in blood pressure known as septic shock.
Managing Low Blood Pressure Day to Day
If your low blood pressure is mild and mainly causes occasional lightheadedness, lifestyle adjustments are the first line of defense. The goal is to increase blood volume and help your body maintain pressure more effectively.
Salt is the most direct tool. Unlike the low-sodium advice given for high blood pressure, people with hypotension are often encouraged to increase salt intake to 3 to 5 grams per day. Salty foods like pickles, olives, broth, jerky, pretzels, and canned soups all contribute. If food alone doesn’t provide enough sodium, salt tablets are an option, typically started at one per day and gradually increased based on how you feel.
Fluid intake matters just as much. Johns Hopkins recommends at least 60 to 100 ounces of fluid daily for people managing low blood pressure. Water works well as long as salt intake is adequate, because salt helps your body retain the fluid rather than just passing it through. Drinking a full glass of water 15 to 30 minutes before standing up or before meals can blunt the drops associated with orthostatic and postprandial hypotension.
Other practical strategies include standing up slowly, especially first thing in the morning. Crossing your legs or squeezing your thigh muscles while standing can push blood back toward your heart. Eating smaller, more frequent meals reduces the blood flow demands that cause post-meal drops. Compression stockings, which gently squeeze the legs, prevent blood from pooling in your lower body.
If a medication is causing the problem, adjusting the dose or switching to an alternative often resolves it. This is one of the most common and most fixable causes of symptomatic low blood pressure.
When Low Blood Pressure Is Serious
A reading of 90/60 with no symptoms and no recent change is rarely a concern. The red flags are sudden onset and accompanying symptoms. Confusion, cold or clammy skin, rapid breathing, a weak pulse, or fainting that doesn’t resolve quickly all suggest blood pressure has dropped to a level where organs aren’t getting the oxygen they need. A sudden, large drop (even from 130 to 90) can be more dangerous than a stable reading of 85, because your body hasn’t had time to adapt.
Repeated fainting episodes, persistent dizziness that limits your daily activities, or symptoms that started after beginning a new medication all warrant a medical evaluation. Blood pressure that drops only when you stand or after meals can usually be managed effectively once the pattern is identified.