What can you do about low blood pressure

How low is too low for blood pressure?

Within certain limits, the lower your blood pressure reading is, the better. There is also no specific number at which day-to-day blood pressure is considered too low, as long as none of the symptoms of trouble are present.

Symptoms of low blood pressure

Most doctors will only consider chronically low blood pressure as dangerous if it causes noticeable signs and symptoms, such as:

• Dizziness or lightheadedness
• Nausea
• Fainting (syncope)
• Dehydration and unusual thirst
• Dehydration can sometimes cause blood pressure to drop. However, dehydration does not always cause low blood pressure. Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can all lead to dehydration, a potentially serious condition in which your body loses more water than you take in. Even mild dehydration (a loss of as little as 1 percent to 2 percent of body weight) can cause weakness, dizziness and fatigue.
• Lack of concentration
• Blurred vision
• Cold, clammy, pale skin
• Rapid, shallow breathing
• Fatigue
• Depression

Underlying causes of low blood pressure

Low blood pressure can occur with:

• Prolonged bed rest
• Pregnancy: During the first 24 weeks of pregnancy, it’s common for blood pressure to drop.
• Decreases in blood volume: A decrease in blood volume can also cause blood pressure to drop. A significant loss of blood from major trauma, dehydration or severe internal bleeding reduces blood volume, leading to a severe drop in blood pressure.
• Certain medications: A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson’s disease; tricyclic antidepressants; erectile dysfunction drugs, particularly in combination with nitroglycerine; narcotics and alcohol. Other prescription and over-the-counter drugs may cause low blood pressure when taken in combination with high blood pressure medications.
• Heart problems: Among the heart conditions that can lead to low blood pressure are an abnormally low heart rate (bradycardia), problems with heart valves, heart attack and heart failure. Your heart may not be able to circulate enough blood to meet your body’s needs.
• Endocrine problems: Such problems include complications with hormone-producing glands in the body’s endocrine systems; specifically, an underactive thyroid (hypothyroidism), parathyroid disease, adrenal insufficiency (Addison’s disease), low blood sugar and, in some cases, diabetes.
• Severe infection (septic shock): Septic shock can occur when bacteria leave the original site of an infection (most often in the lungs, abdomen or urinary tract) and enter the bloodstream. The bacteria then produce toxins that affect blood vessels, leading to a profound and life-threatening decline in blood pressure.
• Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
• Neurally mediated hypotension: Unlike orthostatic hypotension, this disorder causes blood pressure to drop after standing for long periods, leading to symptoms such as dizziness, nausea and fainting. This condition primarily affects young people and occurs because of a miscommunication between the heart and the brain.
• Nutritional deficiencies: A lack of the essential vitamins B-12 and folic acid can cause anemia, which in turn can lead to low blood pressure.

If you notice a sudden decline in blood pressure

A single lower-than-normal reading is not cause for alarm, unless you are experiencing any other symptoms or problems. If you experience any dizziness, lightheadedness, nausea or other symptoms, it’s a good idea to consult with your healthcare provider. To help with your diagnosis, keep a record of your symptoms and activities at the time they occurred.

Is low blood pressure related to low heart rate? Find out.

Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff.

Blood pressure is the force of blood pushing against the walls of your arteries as the heart pumps blood. It is usually described as two numbers: systolic and diastolic. The numbers record blood pressure in millimeters of mercury (mm Hg), with systolic listed above diastolic.

For most adults, a normal blood pressure is usually less than 120/80 mm Hg. Low blood pressure is blood pressure that is lower than 90/60 mm Hg.

Some people have low blood pressure all the time, and it is normal for them. Other people experience a sudden drop in blood pressure or have low blood pressure that may be linked to a health problem. This can be dangerous, as it could mean your heart, brain, or other vital organs are not getting enough blood flow and you are at risk for a heart attack or stroke.

What causes low blood pressure?

Many systems of the body, including organs, hormones, and nerves, regulate blood pressure. For example, the autonomic nervous system sends the “fight-or-flight” signal that, depending on the situation, tells the heart and other systems in the body to increase or decrease blood pressure. Problems with the autonomic nervous system, such as in Parkinson’s disease, can cause low blood pressure.

Other causes of low blood pressure include:

• Blood loss from an injury that causes a sudden drop in blood pressure
• Dehydration
• Diabetes
• Heart problems such as arrhythmias (irregular heartbeat)
• Medicines to treat high blood pressure, depression, or Parkinson’s
• Pregnancy

Older adults also have a higher risk for symptoms of low blood pressure, such as falling, fainting, or dizziness upon standing up or after a meal. Older adults are more likely to develop low blood pressure as a side effect of medicines taken to control high blood pressure.

What are the symptoms?

For many people, low blood pressure goes unnoticed. Others may feel symptoms such as:

• Confusion
• Dizziness or lightheadedness
• Fainting
• Feeling tired or weak
• Blurry vision
• Headache
• Neck or back pain
• Nausea
• Heart palpitations, or feelings that your heart is skipping a beat, fluttering, or beating too hard or too fast

What should you do if you have symptoms?

Sitting down may relieve the symptoms. If your blood pressure drops too low, your body’s vital organs do not get enough oxygen and nutrients. When this happens, low blood pressure can lead to shock, which requires immediate medical attention. Signs of shock include cold and sweaty skin, rapid breathing, a blue skin tone, or a weak and rapid pulse. Call 9-1-1 if you notice signs of shock in yourself or someone else.

Talk to your doctor about your symptoms. Your doctor will use a blood pressure test to diagnose low blood pressure. Other tests may include blood, urine, or imaging tests and a tilt table test if you faint often.

How is it treated?

You may not need treatment for low blood pressure. Depending on your symptoms, treatment may include drinking more fluids to prevent dehydration, taking medicines to raise your blood pressure, or adjusting medicines that cause low blood pressure.

Your doctor may talk to you about lifestyle changes, including changing what and how you eat and how you sit and stand up. Your doctor may also recommend compression stockings if you stand for long periods.

Learn more about Low Blood Pressure from the U.S. National Library of Medicine.

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