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Low blood pressure is a condition in which the force of the blood pushing against the artery walls is too low. It's also called hypotension.
Blood pressure is measured in millimeters of mercury (mm Hg). In general, low blood pressure is a reading lower than 90/60 mm Hg.
What's considered low blood pressure for one person might be OK for someone else though. Low blood pressure might cause no symptoms that you notice. Or it might cause dizziness and fainting. Sometimes, low blood pressure can be life-threatening.
The causes of low blood pressure include dehydration and other serious medical conditions. It's important to find out what's causing low blood pressure so that it can be treated, if needed.
Types of low blood pressure include:
Low blood pressure symptoms can include:
For some people, low blood pressure may be a symptom of an underlying health condition. That's especially so when blood pressure drops suddenly or when low blood pressure occurs with symptoms.
A sudden fall in blood pressure can be dangerous. A change of just 20 mm Hg can make you feel dizzy or faint. For example, those symptoms could happen after a drop in systolic pressure from 110 mm Hg to 90 mm Hg. And big drops can be life-threatening. These can happen for reasons such as serious bleeding, serious infections or allergic reactions.
Extreme low blood pressure can lead to a condition known as shock. Symptoms of shock include:
If you have symptoms of extreme low blood pressure or shock, call 911 or your local emergency number.
Most healthcare professionals consider blood pressure to be too low only if it causes symptoms. Minor dizzy or lightheaded feelings from time to time can be caused by many things. Causes could include spending too much time in the sun or in a hot tub. It's important to see a healthcare professional to find out the cause of your symptoms.
If you often have low blood pressure readings but feel fine, you might not need treatment. Instead, your healthcare professional tracks your health during routine checkups. It can help to keep a record of your symptoms, when they occur and what you're doing at the time.
Low blood pressure has various causes. Some health conditions and the use of certain medicines can cause it. Other factors affect blood pressure as well.
Blood pressure is determined by the amount of blood the heart pumps and the amount of resistance to blood flow in the arteries. A blood pressure reading has two numbers:
The American Heart Association classifies healthy blood pressure as normal. Normal blood pressure usually is lower than 120/80 mm Hg.
Blood pressure varies throughout the day. It depends on:
Blood pressure usually is lowest at night and rises sharply on waking.
Medical conditions that can cause low blood pressure include:
Some medicines can cause low blood pressure, including:
Anyone can have low blood pressure. Risk factors for hypotension include:
Complications of low blood pressure can include:
Severely low blood pressure can lower the body's oxygen levels, which can lead to heart and brain damage.
To find out if you have low blood pressure, also called hypotension, your healthcare professional gives you a physical exam. You're also asked questions about your medical history. The exam includes checking your blood pressure.
You also can measure your blood pressure at home. Checking your blood pressure at home can help your healthcare professional diagnose high blood pressure earlier than usual. Ask a member of your healthcare team to:
If you get a home blood pressure reading at or just below 90/60 mm Hg, it's not always a cause for concern. Your healthcare professional might tell you that the reading is OK for you, especially if you have no symptoms.
Other tests may be done to find out the cause of low blood pressure.
Low blood pressure without symptoms or with only mild symptoms rarely requires treatment.
If low blood pressure causes symptoms, the treatment depends on the cause. For instance, if medicine causes low blood pressure, your healthcare professional may recommend changing or stopping the medicine. Or the dose of medicine might be lowered. Don't change or stop taking your medicine without first talking to your healthcare professional.
If the cause of low blood pressure isn't clear or if no treatment exists, the goal is to raise blood pressure and relieve symptoms. Depending on your age, health and the type of low blood pressure you have, there are various ways to do this:
Medicines. Various medicines can treat low blood pressure that occurs when standing up, also called orthostatic hypotension. For example, the drug fludrocortisone boosts blood volume. It's often used to treat orthostatic hypotension.
If you have long-term orthostatic hypotension, midodrine (Orvaten) may be prescribed to raise standing blood pressure levels. This medicine lessens the ability of the blood vessels to expand, which raises blood pressure.
Depending on the reason for low blood pressure, the following lifestyle and home remedies might help ease or prevent symptoms:
Pay attention to body positions. Gently move from lying flat or squatting to a standing position. Don't sit with legs crossed.
If symptoms of low blood pressure begin while standing, cross the thighs like a pair of scissors and squeeze. Or put one foot on a ledge or chair and lean as far forward as you can. These moves encourage blood flow from the legs to the heart.
Eat small, low-carb meals. To help prevent blood pressure from dropping sharply after meals, eat small meals several times a day. Limit high-carbohydrate foods such as potatoes, rice, pasta and bread.
A healthcare professional also might recommend drinking one or two strong cups of caffeinated coffee or tea with breakfast. Caffeine can cause dehydration, though, so be sure to drink plenty of water and other fluids without caffeine.
You don't have to take any special steps to prepare to have your blood pressure checked. Don't stop taking medicines you think might affect your blood pressure without a healthcare professional's advice.
Here's some information to help you get ready for your appointment.
Make a list of:
For low blood pressure, basic questions to ask your healthcare professional include:
Feel free to ask other questions.
Your healthcare professional is likely to ask you questions, including: