Blood pressure changes throughout the day and varies from person to person. Various factors affect blood pressure, including your body position, breathing rhythm, stress level, physical activity, medications, what you eat or drink, and the time of the day (blood pressure is usually lowest at night when you sleep and rises when you wake up). In healthy individuals, your body responds and adapts to these changes to keep your blood pressure within a normal range. This ensures that vital organs, such as your brain and kidneys, receive a constant blood flow and nutrient supply.
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A 2015 review of several studies found that restoring blood vitamin D levels by using supplements (more than 1,000 IU per day) reduced blood pressure in hypertensive individuals when they had existing vitamin D deficiency.[167] The results also demonstrated a correlation of chronically low vitamin D levels with a higher chance of becoming hypertensive. Supplementation with vitamin D over 18 months in normotensive individuals with vitamin D deficiency did not significantly affect blood pressure.[167]
For example, in a hypertensive patient with asthma, it may be inadvisable to prescribe a beta blocker, as these drugs can aggravate that respiratory condition. Similarly, in patients prone to constipation (the elderly, for example) use of certain calcium channel blockers might best be avoided -- along with diuretics -- as both these classes of drugs can inhibit proper bowel function.
Weakened heart muscle can cause the heart to fail and reduce the amount of blood it pumps. One common cause of weakened heart muscle is the death of a large portion of the heart's muscle due to a single, large heart attack or repeated smaller heart attacks. Other examples of conditions that can weaken the ability of the heart to pump blood include medications toxic to the heart, infections of the muscle of the heart by viruses (myocarditis), and diseases of the heart's valves such as aortic stenosis that reduce the flow of blood from the heart and into the arteries.
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.
As for when to check your blood pressure, the most important thing is to do it consistently the same time of the day (ask the doctor which time he prefers and also what time in relation to taking your medication). The following article has a lot of good information for someone just starting to monitor their blood pressure: https://www.drugs.com/cg/how-to-take-a-blood-pressure.html
There are a number of factors that likely work together to cause high blood pressure. A family history of high blood pressure can make you more likely to develop the condition, so genetics likely plays a role. High salt intake (too much salt in the diet) or salt sensitivity occurs in some people, which can lead to hypertension, particularly in the elderly, African Americans, people who are obese, or people with chronic kidney (renal) disease.

Sodium, a chemical found in salt, raises blood pressure by promoting the retention of fluid by the body. This increases the workload on the heart. The American Heart Association recommends an upper daily limit for sodium consumption of 1,500 mg. Checking food labels and menus can help you calculate how much sodium you are consuming. Processed foods are particularly high in sodium and make up about 75% of our sodium intake. Among these, lunch meats and canned soups have some of the highest levels of dietary sodium.


Your doctor can help you measure and track your blood pressure to confirm whether it’s too high. You may need to start taking medications if your blood pressure doesn’t improve after one month of following a healthy lifestyle, especially if you’re already at high risk for heart disease. If you’re at lower risk, your doctor may want to follow up in three to six months after you’ve adopted more healthy habits.
Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2017; pii: S0735-1097(17)41519-1. PMID: 29146535 www.ncbi.nlm.nih.gov/pubmed/29146535.
Hypertension results from a complex interaction of genes and environmental factors. Numerous common genetic variants with small effects on blood pressure have been identified[34] as well as some rare genetic variants with large effects on blood pressure.[35] Also, genome-wide association studies (GWAS) have identified 35 genetic loci related to blood pressure; 12 of these genetic loci influencing blood pressure were newly found.[36] Sentinel SNP for each new genetic locus identified has shown an association with DNA methylation at multiple nearby CpG sites. These sentinel SNP are located within genes related to vascular smooth muscle and renal function. DNA methylation might affect in some way linking common genetic variation to multiple phenotypes even though mechanisms underlying these associations are not understood. Single variant test performed in this study for the 35 sentinel SNP (known and new) showed that genetic variants singly or in aggregate contribute to risk of clinical phenotypes related to high blood pressure.[36] 

When blood pressure is measured, there are two numbers for each reading: for example, "120 over 80" is written as 120/80. This is because each heartbeat sends a pressure wave through the bloodstream. The higher number (systolic blood pressure) is the peak of the wave, when your heart contracts (the loud "thump" when you listen to your heartbeat). The lower number (diastolic blood pressure) is the lower "dip" or trough of the wave, when your heart relaxes.

Everything you need to know about hypertension Hypertension or high blood pressure can lead to heart disease, stroke, and death and is a major global health concern. A range of risk factors may increase the chances of a person developing hypertension, but can it be prevented? Read on to find out what causes hypertension, its symptoms, types, and how to prevent it. Read now
Your doctor may diagnose you with high blood pressure when you have consistent systolic readings of 140 mm Hg or higher or diastolic readings of 90 mm Hg or higher. Based on research, your doctor may also consider you to have high blood pressure if you are an adult or child age 13 or older who has consistent systolic readings of 130 to 139 mm Hg or diastolic readings of 80 to 89 mm Hg and you have other cardiovascular risk factors.
High blood pressure is a common disease in which blood flows through blood vessels, or arteries, at higher than normal pressures. Blood pressure is the force of blood pushing against the walls of your arteries as the heart pumps blood. High blood pressure, sometimes called hypertension, is when this force against the artery walls is too high. Your doctor may diagnose you with high blood pressure if you have consistently high blood pressure readings.
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