Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). This NHLBI study began in 1994 and lasted eight years. People with high blood pressure enrolled in one part of the study and people with high blood cholesterol enrolled in another part of the study. ALLHAT’s findings have informed how we treat high blood pressure and high blood cholesterol. Visit Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial for more information about all research activities and advances from this study.
The most widely used classification of blood pressure readings currently is given in the table below. Stratification of the blood pressure readings into different categories is important because of increasing severity of high blood pressure readings and different approach to the treatment of these conditions. Another table below the first one gives the blood pressure chart with different categories of the blood pressure, symptoms and the treatment.
Effective lifestyle modification may lower blood pressure as much as an individual antihypertensive medication. Combinations of two or more lifestyle modifications can achieve even better results.[87] There is considerable evidence that reducing dietary salt intake lowers blood pressure, but whether this translates into a reduction in mortality and cardiovascular disease remains uncertain.[96] Estimated sodium intake ≥6g/day and <3g/day are both associated with high risk of death or major cardiovascular disease, but the association between high sodium intake and adverse outcomes is only observed in people with hypertension.[97] Consequently, in the absence of results from randomized controlled trials, the wisdom of reducing levels of dietary salt intake below 3g/day has been questioned.[96]
Primary (or essential) hypertension is when the cause is unknown. The majority of hypertension cases are primary. When there is an underlying problem such as kidney disease or hormonal disorders that can cause hypertension, it is called secondary hypertension. When it is possible to correct the underlying cause, high blood pressure usually improves and may even return to normal.

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.
Normal blood pressure is below 120/80. New guidelines from the American Heart Association (AHA) and the American College of Cardiology (ACC) published in November of 2017 consider blood pressure elevated between 120/80 and 129/80. High blood pressure or hypertension is now classified as stage 1 if your systolic reading falls between 130 and 139 or your diastolic reading is between 80 and 89. A measure of 140/90 or higher is now considered stage 2 hypertension. A hypertensive crisis is defined as a systolic rate over 180 or a diastolic rate above 120. An elevated blood pressure means that the heart must work harder to pump blood. High blood pressure can also damage the walls of the arteries. Over time, hypertension increases the risk of heart disease, kidney disease, and stroke. It is estimated that one in three adults in America are affected by hypertension.
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.
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