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.
The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discovery to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including high blood pressure. Learn about the current and future NHLBI efforts to improve health through research and scientific discovery.
The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.
Blood pressure is the force of your blood pushing against the walls of your arteries. Each time your heart beats, it pumps out blood into the arteries. Your blood pressure is highest when your heart beats, pumping the blood. This is called systolic pressure. When your heart is at rest, between beats, your blood pressure falls. This is the diastolic pressure. Your blood pressure reading uses these two numbers. Usually they're written one above or before the other, such as 120/80. If your blood pressure reading is 90/60 or lower, you have low blood pressure.
Hypertension is diagnosed on the basis of a persistently high resting blood pressure. The American Heart Association recommends at least three resting measurements on at least two separate health care visits. The UK National Institute for Health and Care Excellence recommends ambulatory blood pressure monitoring to confirm the diagnosis of hypertension if a clinic blood pressure is 140/90 mmHg or higher.
After menopause, however, blood pressure increases in women to levels even higher than in men. Hormone replacement therapy in most cases does not significantly reduce blood pressure in postmenopausal women, suggesting that the loss of estrogens may not be the only component involved in the higher blood pressure in women after menopause. In contrast, androgens may decrease only slightly, if at all, in postmenopausal women.
Hypertension occurs in around 0.2 to 3% of newborns; however, blood pressure is not measured routinely in healthy newborns. Hypertension is more common in high risk newborns. A variety of factors, such as gestational age, postconceptional age and birth weight needs to be taken into account when deciding if a blood pressure is normal in a newborn.
Angiotensin receptor blockers prevent the actions of angiotensin II on the arteries. This means the arteries stay more open and blood pressure is lowered. ARBs can take a few weeks to work. Side effects can include dizziness, muscle cramps, insomnia, and elevated potassium levels. As with ACE inhibitors, women who are pregnant, planning to get pregnant, or breastfeeding should not take ARBs.
Although the guidelines do not change the traditional definition of high blood pressure, they do call for more aggressive treatment of the condition through the use of a combination of blood-pressure lowering medications. In fact, they say that most people with high blood pressure will require two or more drugs to achieve a blood pressure goal of less than 140/90. The blood pressure goal in people with diabetes or kidney disease should be less than 130/80.
Your total blood pressure reading is determined by measuring your systolic and diastolic blood pressures. Systolic blood pressure, the top number, measures the force your heart exerts on the walls of your arteries each time it beats. Diastolic blood pressure, the bottom number, measures the force your heart exerts on the walls of your arteries in between beats.
^ Ostchega Y, Dillon CF, Hughes JP, Carroll M, Yoon S (July 2007). "Trends in hypertension prevalence, awareness, treatment, and control in older U.S. adults: data from the National Health and Nutrition Examination Survey 1988 to 2004". Journal of the American Geriatrics Society. 55 (7): 1056–65. doi:10.1111/j.1532-5415.2007.01215.x. PMID 17608879.
Health issues may happen; however, when a person's blood pressure suddenly drops and their brain is deprived of an adequate blood supply. The condition may lead to lightheadedness or dizziness. A sudden drop in blood pressure usually happens in a person who has risen from a prone or sitting position to a standing one. When this occurs it is referred to as, 'orthostatic hypotension,' or, 'postural hypotension.' Another type of low blood pressure may happen when a person stands for extended periods of time; it is referred to as, 'neurally mediated hypotension.'
If these lifestyle changes don't lower your blood pressure to a safe level, your doctor will also prescribe medicine. You may try several kinds or combinations of medicines before finding a plan that works best for you. Medicine can control your blood pressure, but it can't cure it. You will likely need to take medicine for the rest of your life. Plan with your doctor how to manage your blood pressure.
It has been shown that meditation and other relaxation techniques can help lower blood pressure. Yoga, tai chi, and breathing exercises can also help reduce blood pressure. It's best when these are combined with changes in diet and exercise. Tell your doctor if you are taking any herbal remedies, since some of these preparations can actually raise blood pressure or interact with your blood pressure medications. The following are supplements that may lower blood pressure:
When the systolic pressure drops below 90 mm Hg and the diastolic pressure falls below 60 mm Hg, this is categorized as low blood pressure. Some people may have low pressure all the time and this may be normal for them. If they do not experience any other signs or symptoms, medical treatment may not be necessary for them. Low blood pressure becomes a concern when it is accompanied by noticeable symptoms, such as dizziness, fainting and, in severe cases, shock. When this occurs, people should seek medical attention to determine if an underlying condition may be responsible for their hypotension.