Blood Pressure – Causes, Prevention & Treatment

Blood pressure is a key indicator of your health. This is why it is checked at every visit with a healthcare professional. Understanding this measurement will help you make sense of both your blood pressure and your healthcare professional’s advice. This article series will explain what blood pressure is, how to correctly measure it, and what to do when it is high.

Blood Pressure Basics

Blood carries oxygen and nutrients to all the organs and tissues in your body. The heart functions as a pump, squeezing to push blood forward through your blood vessels and then relaxing to refill as blood returns. The flow of blood exerts pressure on the inner lining of blood vessels, and this pressure fluctuates as the heart squeezes and relaxes. Blood vessels are not like simple pipes — they are muscular, living tissues that respond to changes in blood pressure and adapt over time.

Checking blood pressure involves two measurements: one while the heart is squeezing, known as systolic pressure, and another while the heart is relaxing, known as diastolic pressure. Pressure is measured in units called millimeters of Mercury (mm Hg), which describes the height of mercury in a tube. We still use this unit of measure today, even though blood pressure is frequently checked using digital devices. A normal resting blood pressure is generally below 120 mm Hg systolic, and 80 mm Hg diastolic. This is commonly shortened to 120/80.

It is important to specify “resting” blood pressure because blood pressure fluctuates from minute to minute throughout the day depending on what you are doing. It is normally lower while asleep and higher while awake. Psychological or emotional stress, pain, and physical effort such as when we exercise, normally increase blood pressure. Relaxing, deep breathing, and meditating can cause blood pressure to temporarily decrease. Large, sudden drops in blood pressure cause people to briefly lose consciousness in certain situations.

Blood pressure is influenced by multiple factors, including how much the heart is pumping (known as cardiac output), as well as how tightly the muscular blood vessels are squeezed (known as vascular resistance). These two factors are primarily regulated by the nervous system and a variety of hormones. The total volume of blood contained in the system also influences blood pressure. The kidneys regulate this volume by controlling how much salt and water are urinated out or retained in the body. Treatments for high blood pressure work by impacting one or more of these factors; we will discuss these further in part 2.

What is Hypertension?

Hypertension, commonly known as “high blood pressure”, is the condition of having a resting blood pressure measurement that is persistently higher than normal. Note again the emphasis on resting blood pressure, and the long-term persistence of this elevation in blood pressure. This is different from having brief, temporary increases in blood pressure when you feel anxious or perform exercise that normalize afterwards. 

Having a persistently high resting blood pressure over many years can cause progressive damage to the heart and blood vessels throughout the body. This increases the risk of experiencing a stroke, heart attack, heart failure, and many other health complications that can cause disability or death. Lewington 2002 High blood pressure affects half of all adults in the United States and is the leading contributor to premature death worldwide, accounting for 13% of deaths globally each year. WHO 2009 High blood pressure does not cause symptoms in most people, so a large proportion of these people do not know that they have it. The following table illustrates the different stages of high blood pressure.

High blood pressure can have many different causes, which we will discuss in further detail in part 2. These include things like genetics, smoking and alcohol use, overweight and obesity, physical inactivity, medications, and diet quality. Other underlying medical conditions like sleep apnea and kidney disease can also contribute to high blood pressure.

High blood pressure does not always clearly present itself. Some people may have high blood pressure when measured in a healthcare setting like a clinic or hospital, but maintain normal blood pressure when going about their everyday life. This is called “white coat hypertension”. Even though people with this condition have normal resting blood pressures when outside of a clinic setting, they still have higher cardiovascular risk if left untreated compared to people who have normal resting blood pressure all the time. Cohen 2019 These findings are not well-understood, but we do know that people with white coat hypertension have much higher risk of developing sustained high blood pressure over the following decade. Mancia 2013 People with white coat hypertension benefit from blood-pressure lowering treatments. As a result, white coat hypertension is not something that should be ignored.

It is also possible for individuals to have normal blood pressure in a healthcare setting despite having high blood pressure when going about their everyday life. This is called “masked hypertension”. Trudel 2019 This is a particularly risky situation given how likely it is that the diagnosis is missed, leading to years of untreated high blood pressure. As a result, it is recommended to periodically check your blood pressure outside of the doctor’s office.

Physical activity produces a temporary increase in blood pressure, with more vigorous activities usually creating a higher increase. This is especially true with lifting weights. Holding your breath and exerting yourself against a resistance causes a large momentary spike in pressure. It does not increase your long-term resting blood pressure, which means lifting weights does not cause hypertension. In fact, the brief variations of blood pressure during lifting weights provide a useful stress to the cardiovascular system, and can lower resting blood pressure over time. This is an adaptation that is good for us, and means that even people with hypertension can benefit from strength training.

How do I check my blood pressure?

Since we are most concerned with resting blood pressure over the long term, diagnosing hypertension requires multiple blood pressure measurements over time. Most people have their blood pressure checked in a healthcare office setting. If this office measurement is high, additional measurements outside the office setting are recommended to confirm before starting treatment. USPSTF 2021 Checking blood pressure at home can be an excellent option, but requires careful measurement technique with the appropriate equipment.

The most accurate way to measure your blood pressure at home involves using an automatic blood pressure machine under the correct conditions. A listing of approved devices is available at ValidateBP.org.

First, the blood pressure cuff should be appropriately sized for your arms — a cuff that is too small will give falsely high readings, and a cuff that is too large will give falsely low numbers. We can correlate the circumference of the upper arm (for example, using a measuring tape around the biceps), to an appropriate cuff size, as shown in the following table. AHA Fortunately, most devices are now sold with variable-size cuffs that will fit most arms from the “small adult” to “large adult” range.

When ready measure your blood pressure, follow these steps. For a graphical illustration, see here.

When evaluating people for high blood pressure using home measurements we recommend a minimum of three days of measurements, two in the morning and two in the evening on each day. Bello 2018 Even if the resting blood pressure measurements are high, this can be addressed gradually over time with a primary care doctor if no other symptoms are present. Emergency care is rarely needed, only in situations where symptoms like chest pain, shortness of breath, vision changes, confusion, or stroke-like symptoms are present, but otherwise can safely be managed in the primary care setting.

Conditions like white coat hypertension and masked hypertension require blood pressure monitoring outside of the doctor’s office. The preferred method is known as “24-hour ambulatory blood pressure monitoring”, where a special blood pressure monitor is worn continuously for 24 hours and a series of measurements are taken automatically as you go about your day. However, properly calibrated home blood pressure machines can be used if 24-hour monitors are not available. Carefully measuring blood pressure as outlined above, twice in the morning and twice in the evening for at least 3 days, can provide useful information to help your doctor make recommendations.

Factors that Causes High Blood Pressure

• Body weight and body fat
• Physical activity habits
• Diet quality
• Sleep quality
• Drugs & medicines that increase blood pressure
• Medical conditions that increase blood pressure
• Age and Genetics

Body Weight and Body Fat

Body fat has a powerful effect on blood pressure — especially fat accumulated in the belly. Excess body fat releases hormones that activate the nervous system and make blood vessels squeeze tighter, while also increasing the amount of salt and water retained by the kidneys. These changes all result in higher blood pressure. One easy method to check for excess body fat is using a waist measurement.

Weight loss is one of the most effective ways to lower blood pressure. A sustained weight loss of just 5–10% of body weight can significantly lower blood pressure. Stevens 2001 A rough rule of thumb is that every pound of weight lost can lower blood pressure by about 1 point. However, there is variation in how people’s blood pressure changes with weight loss and even with successful weight loss, some people may need additional strategies to keep their blood pressure controlled over the long term. Sjostrom 2000 Laaksonen 2003

Aiming for a waist circumference goal is often more useful than a specific body weight. For example, a male of European descent should aim to lower his waist measurement to below 40 inches (101 centimeters), whereas a woman of Asian descent should aim for 31.5 inches (80 centimeters) or less. These are just two, somewhat imperfectly defined groups of people. For waist circumference cut-offs in other demographics, see our article on the topic.

Losing weight and keeping it off involves behavior change that can be very challenging. Our bodies often fight against us during weight loss by increasing appetite and decreasing feelings of fullness. There are highly effective medical treatments available for people who struggle with achieving and sustaining weight loss. While there is an unfortunate stigma against these treatments, it is not a sign of weakness to use medical help when you need it.

Physical Activity

Increasing physical activity decreases blood vessel stiffness, has beneficial effects on levels of circulating hormones and inflammation, and results in better regulation of appetite to maintain weight loss.

Current Physical Activity Guidelines recommend certain amounts of strength training and aerobic activity each week. Piercy 2018 Less than one-quarter of U.S. adults currently meet these guidelines. Physical inactivity is one of the major contributors to high blood pressure and premature death worldwide, so this is an important focus for improving health.

Performing both strength training and aerobic exercise has a greater effect on lowering blood pressure than performing either one by itself. Combining these forms of exercise can lower blood pressure to a similar degree as commonly used medicines. Naci 2019

Any increase in physical activity from a sedentary lifestyle will help, and these benefits increase further the more activity you do. Even if meeting these recommendations is difficult, the more you exercise, the greater the benefits to your health. For more discussion on beginning exercise, see our beginner prescription article.

Diet

Certain diets can impact blood volume and how tightly our blood vessels squeeze, in addition to their effects on body weight and body fat. As a result, food choices can improve blood pressure whether or not weight loss occurs.

Table salt (sodium chloride) can increase blood pressure for some people when they eat high amounts of it. Lowering sodium intake, while also increasing potassium intake, generally improves health and reduces the risk of heart disease. Cook 2014 Cook 2009 Cook 2020 Neal 2021 The US Department of Agriculture recommends that adults consume 4,700 mg of potassium per day, and less than 2,300 mg of sodium per day. There can be exceptions to this sodium recommendation for hard-training and competitive athletes, but this does not apply to most people. Unfortunately, these kinds of milligram targets of sodium and potassium are often not helpful for communicating what foods people should actually eat.

Highly processed foods have several characteristics that make them problematic for people struggling with their blood pressure. They are tasty, cheap, high in calories, not very filling, and often heavily salted. Replacing these kinds of foods with vegetables, fruits, legumes, nuts, whole grains, dairy products, and lean sources of protein such as fish is an excellent strategy to lower sodium intake, increase potassium and fiber intake, and ultimately lower blood pressure.

The “DASH Diet” is one of the most well-established diets that consistently improves blood pressure in humans, regardless of whether or not they have high blood pressure, and regardless whether weight loss occurs. Filippou 2020 However, there are many other diet patterns that can improve blood pressure and other aspects of health. Overall, our diet recommendations from the cholesterol series conveniently apply here too.

Sleep

Blood pressure can rise if people are not sleeping enough, or if their sleep is of poor quality. This happens due to the effects of insufficient sleep on the heart and nervous system. People differ in the amount of sleep that they need for health; this also changes across the lifespan, with babies and young children generally needing more sleep than adults. For adults, targeting approximately 7–7.5 hours of sleep per night on a regular basis is a good starting recommendation.

In addition to sleeping long enough, ensuring quality sleep is also important. Bedtime habits to improve sleep quality are known as “sleep hygiene,” although this subject is beyond what we will cover here. We do want to address a common condition that causes high blood pressure called Obstructive Sleep Apnea. Obstructive Sleep Apnea, or just sleep apnea, is a disorder where people periodically stop breathing in their sleep without knowing it. Sleep apnea can also cause fatigue, morning headaches, heart and lung problems, and low testosterone. Men are at higher risk than women, as are those who snore, who are older, or who have excess body fat, but people without these risk factors can still have the condition. Treating sleep apnea improves blood pressure, and many patients can reduce their need for blood pressure-lowering medicines. We recommend screening all people with high blood pressure for sleep apnea using the STOP-BANG tool and, if a person scores high enough, discussing sleep testing with their doctor.

Other Medical Conditions, Age, and Genetics

High blood pressure often occurs alongside other illnesses and conditions, which can compound the problem. These include, but are not limited to:

• Kidney disease, which is a very general term. Because kidneys are intimately associated with blood pressure management, compromised kidney function often affects it.
• Hormone disorders, especially those involving aldosterone. Not everyone needs their aldosterone levels checked, but there is a case to be made for broader testing of those with hypertension. Libianto 2020  
• Pregnancy can lead to changes in blood pressure and becoming pregnant while hypertensive increases risks of complications to the mother and child. 

When high blood pressure is diagnosed in young people, or is resistant to treatment with multiple medications, some of these additional factors may need to be addressed. All these situations require diagnosis and care from a physician.

As people get older, they often decrease their level of physical activity. This causes loss of muscle mass, and gain of body fat. Further, blood vessels gradually stiffen with age. While we cannot modify our age to improve blood pressure, all the strategies we’ve discussed apply. Exercise can improve this stiffness, and making the diet substitutions described above can promote blood vessel relaxation.

About 30 to 50 percent of the variation in blood pressure is explained by people’s genes. People with genetically high blood pressure are typically unable to get it fully controlled through diet and exercise alone. This is not their fault, nor is it due to a lack of effort or willpower – it simply reflects the genes they inherited. This does not mean that people with genetic contributors to high blood pressure should not make the same kinds of lifestyle changes we have discussed above, but rather that these efforts may not be enough to get them all the way down to a healthy resting blood pressure. Medications are particularly helpful in these situations.

Drugs and Medicines

The use of alcohol, tobacco products, and other drugs can all influence blood pressure for the worse. Reducing or stopping use of these products can result in significant improvements in blood pressure and overall health, but quitting can be very challenging for many individuals. This is an entire topic unto itself, and we cannot do it justice here. Specific treatments are available to help increase the odds of successfully quitting tobacco and alcohol and seeking professional help increases the chance of success.

Similarly, lots of medicines can cause increases in blood pressure. Examples of these are listed below:

• Stimulants (such as those used for attention deficit disorder or for sports performance)
• Non-steroidal anti-inflammatory drugs (NSAIDs like Ibuprofen or Naproxen, often used to treat pain)
• Oral birth control pills
• Anabolic steroids, erythropoietin (EPO)
• Supplements, herbals, and other substances commonly used by athletes may contain ingredients or contaminants that cause high blood pressure

Medications to Treat High Blood Pressure

People can have high blood pressure despite low body fat, high physical activity, high diet quality, good sleep, and no other medical causes for high blood pressure. At this point it is time to look at using medications to lower blood pressure. Discussions of drugs tend to use a lot of jargon and unfamiliar names, but we will do our best to make it understandable.

Blood pressure-lowering medicines target the regulators of blood pressure we have discussed so far, including the nervous system, heart, blood vessels, hormones, and kidneys. Diuretics cause more salt and water to be released in the urine (although this is a significant over-simplification). Blood vessel “dilators” directly cause relaxation of arteries, lowering blood pressure. The following table illustrates common medications that are preferred for treating high blood pressure in most people.

Many other medicines are generally not the first choice for treating high blood pressure compared with those in the table above, unless a person has other specific health conditions.

For example, beta blockers like metoprolol primarily work on the heart, and are preferred in patients with certain heart conditions. Loop diuretics like furosemide cause salt and water to be urinated out; these are often used in patients with kidney and heart disease. Alpha blockers like doxazosin and terazosin, as well as other medicines like hydralazine, clonidine, and nitrates generally work by relaxing blood vessels; each have their own niche uses.

Blood pressure drugs often show the effects of diminishing returns. A small dose of a medication will tend to produce a significant effect. Increasing the dose will continue to lower blood pressure, but not nearly as much as the initial exposure. As dosage increases, the risk for side effects also increases. Researchers have looked at using small doses of multiple medicines to exploit this. This strategy can result in the same or better reduction in blood pressure, with lower chances of experiencing side effects. Chow 2021

There is no free ride, however. Taking two, three, or four pills is more complicated and demanding than taking one. If someone is already on multiple other medications, this might be a less attractive option. Doctors must weigh these trade-offs when making prescription decisions with patients. What will provide the greatest potential benefits for the patient, with the least amount of risk? The answers are often not straightforward.

This hints at some of the complexities of managing this condition. Lifestyle changes are the first choice in most situations. For some people lifestyle changes are either not feasible, or they do not lower blood pressure enough. Remember that untreated high blood pressure kills a lot of people every year and sickens, or makes life very difficult, for many more. The goal is to maximize benefit and minimize harm. No one is giving out awards for going through life without having a prescription to fill. Be active, work on making lifestyle changes, and if you and your doctor decide that medications are needed, be open to that.

Finally, there are special considerations for treating high blood pressure in athletes that are worth noting. All diuretics are banned substances by anti-doping agencies in sport. Beta blockers are also banned substances in precision sports since they can calm anxiety and improve focus — but can also worsen exercise performance by limiting maximum heart rate. They are not the best choice in many athletes for these reasons. If these medicines are specifically needed for a competitive athlete, a Therapeutic Use Exemption will be required for drug-tested sporting events.

Conclusion

We can only speak in generalities about managing blood pressure because of the variability between people and the complexities of the topic. We are complex organisms and treatment decisions require taking a broad look at the person and considering the multiple contributing factors at play. However, there are some useful principles to keep in mind.

1. High blood pressure is a serious medical condition that is one of the leading causes of death and illness across the globe. It should be diagnosed and treated. Blood pressure is one of the few, regular medical screenings we recommend for all people. 
2. There are multiple lifestyle factors that we can modify to improve blood pressure. These include meeting the physical activity guidelines for both strength and aerobic exercise, decreasing waist measurements to target ranges, improving diet quality as described above, and getting sufficient high-quality sleep. These are important and powerful interventions that are appropriate for almost everyone, even if the implementation will vary between people. Exercise and dietary changes can lower blood pressure by as much as medications, especially for people that are currently inactive.
3. Even with excellent lifestyle habits, some people will still have persistently high blood pressure due to genetics or other undiagnosed medical conditions like obstructive sleep apnea. If no clear causes for high blood pressure are found, this is often a situation where blood pressure-lowering medicines are necessary.
4. There are numerous medicines available to lower blood pressure. While many people have a reluctance to take medicines, they can provide real benefit, especially when used alongside lifestyle modifications. Using very low doses of multiple medicines can be an excellent way to achieve the goal blood pressure, with fewer risks of side effects than using high doses of a single medicine.

With the background provided here, you hopefully have more information to determine if you are at risk for this condition and whether you should inquire with your physician. You also have some ideas about the treatments available. Even if you are unsure if you have high blood pressure, making lifestyle adjustments, particularly increasing how much you exercise, is likely an excellent course of action. Be active and enjoy the benefits, including lower blood pressure. 

Thank you to Tom Campitelli for his assistance in editing this article.