Overview
Blood pressure (BP) refers to the force that blood exerts on the blood vessels as it circulates through your body. It plays a central role in heart health: cardiovascular disease risk is strongly associated with an increase in blood pressure, even when BP is within normal range.[1][2]
As your blood pressure increases, it strains your blood vessels and heart. If it remains too high (hypertension), this can increase your risk for heart attacks, strokes, vascular diseases, eye damage, kidney disease, and more.
As your BP drops, the pressure on the blood vessel walls decreases. If it remains too low (hypotension), you may not get enough oxygen to critical parts of your body, such as the brain and heart.
There are multiple risk factors that can contribute to the development of high blood pressure.
Age: As you age, blood pressure tends to go up.
Family history: Nearly 100 genetic variations have been associated with high blood pressure. While a family history of high BP raises your risk, the exact pattern of genetic inheritance is not known.
Lifestyle: Too much sodium (salt), insufficient potassium, not enough exercise, excessive alcohol intake, and smoking can all contribute to high blood pressure.
Race/ethnicity: Black adults experience high blood pressure more frequently.
Sex: Prior to age 55, males are more likely to develop high blood pressure. After 55, females are more likely to develop it.
Weight: People who carry too much fat have an increased risk of high blood pressure.
How are blood pressure levels assessed?
Blood pressure is most commonly measured using a blood pressure monitor or gauge (where a cuff is placed around your upper arm). It can be measured either in a single sitting or via ambulatory blood pressure monitoring (ABPM) over 24 hours with a leave-on cuff. The latter is likely to be more accurate and result in fewer anomalous measurements since blood pressure can naturally fluctuate throughout the day.
Blood pressure is reported in two numbers; e.g., 120/80 mmHg (millimeters of mercury — a unit of pressure).
The first number, systolic blood pressure, tells us how much pressure your blood is exerting against the arterial walls when your heart contracts.
The second number, diastolic blood pressure, signifies how much pressure your blood is exerting when the heart is relaxed and refilling with blood.
Blood pressure measurements are generally divided into the five categories below.
| CATEGORY | SYSTOLIC | DIASTOLIC |
|---|---|---|
Low blood pressure | ||
Normal blood pressure | ||
Elevated blood pressure | ||
Stage 1 hypertension | ||
Stage 2 hypertension |
Adapted from Whelton et al. Hypertension. 2018.[3]
In adults 65 or older, a blood pressure goal of 125–130 systolic and <80 diastolic is recommended.
Preparing for your test
If you are using one single-sitting blood pressure assessment, there are a few steps to follow to ensure you receive an accurate measurement.
Prior to the test, rest for 5–10 minutes in a seated position.
Do not take a reading if you are stressed or have consumed stimulants (e.g., caffeine or nicotine) or exercised in the past hour.
Uncross your legs and place your feet flat on the floor.
Support the arm you’re taking the measurement with so that your upper arm is about at heart level.
Place the cuff on your bare skin, not over clothing.
Place the lower edge of the cuff about 2.5 centimeters (cm, or 1 inch) above your elbow crease.
Remain seated and still while the cuff inflates and deflates.
If you are taking multiple readings in succession, space them out by at least 1 minute. Remain seated during this time.
What are the symptoms of abnormal blood pressure levels?
Perceiving changes in blood pressure can be tricky, as physical symptoms are typically absent. Most people will only discover they have abnormal BP during a health checkup.
When blood pressure becomes very high or low, some detectable symptoms can manifest, as seen below.
| VERY LOW BLOOD PRESSURE | VERY HIGH BLOOD PRESSURE |
|---|---|
Confusion | Blurred vision |
Fainting | Confusion |
Headaches or migraines | Dizziness |
Nausea | Lightheadedness |
Vision fluctuations | Nausea |
Vomiting | Nosebleeds |
Sleepiness | |
Vomiting | |
Weakness |
What affects blood pressure?
Supplements
Supplements may affect blood pressure by improving the ability of blood vessels to dilate due to nitric oxide signaling; inhibiting angiotensin, which causes vasoconstriction, or the narrowing of blood vessels; modifying blood volume; protecting blood vessels; or playing a role in the function of endothelial cells that line your blood vessels.
Supplements such as cocoa, fish oil, garlic, and nitrate can help decrease high blood pressure, while stimulants, such as caffeine, ephedrine, nicotine, synephrine, and yohimbine, can increase blood pressure.
The table below displays an analysis of human studies and indicates how individual supplements may affect blood pressure.
Diets & foods
Sodium is a known regulator of blood pressure. Sodium concentrations are sensed by a group of cells in the kidneys called the macula densa.[4] When your blood sodium concentration increases, these cells activate the renin-angiotensin-aldosterone system, which helps regulate sodium levels.
In short, increased intake of high-sodium foods causes your body to hold onto more water, which increases your blood pressure. This extra pressure puts a strain on your cardiovascular system, which can eventually lead to worse cardiovascular disease outcomes over time.
Sodium restriction may reduce both systolic and diastolic blood pressure, primarily among people starting out with higher blood pressure. Although there can be small benefits among people with lower blood pressure, these effects are usually either not clinically relevant (or possibly nonexistent).
Lifestyle
Clinically, even a small, 2–5 mmHg decrease in systolic blood pressure (SBP) can noticeably reduce cardiovascular disease and mortality rate.[5] High blood pressure can be handled using a multitude of approaches, which are often better in combination than they are in isolation.
Here are how individual treatments alone can affect your blood pressure.[6][7][8][9][10]
| INTERVENTION | SBP REDUCTION (mmHg) | CAVEAT |
|---|---|---|
Increased protein intake | 2–3 | Depends on baseline protein intake; minimum effective dose is unknown |
Weight loss | 5–20 | About 1 mmHg for every 1 kg (2.2 lb) reduction in body weight; effect eventually plateaus as body weight normalizes |
DASH diet | 8–14 | Depends on the baseline diet pattern; DASH diet tested was rich in fruits and vegetables and low in fat and saturated fat |
Reduced salt intake | 2–8 | Depends on baseline salt intake; aim for reduction of at least 1,000 mg (1 g) |
Increased potassium intake | 4–5 | With an intake of 3,500–5,000 mg (3.5–5 g) per day, particularly from potassium-rich foods |
Increased physical activity | 4–9 | A mix of endurance and resistance may be more effective than either alone |
Reduced alcohol intake | 2–4 | Depends on baseline alcohol intake |
* Greater improvements will be seen in those with higher starting systolic blood pressure
kg = kilograms; lb = pounds; mg = milligrams; g = grams
Stress levels can also influence blood pressure. Stress management techniques — listening to binaural beats or music, exercising, meditation, yoga — may help reduce stress levels, which may reduce your blood pressure.
Pregnancy
Hypertension during pregnancy can be divided into three categories, all of which should be monitored by a physician.
Gestational hypertension develops during pregnancy after the 20th week. In some cases, it will disappear 12 weeks after giving birth. However, this can raise your risk of high blood pressure in the future.
Chronic hypertension develops before pregnancy or before the 20th week. In some cases, chronic hypertension may develop into preeclampsia.
Preeclampsia is a sharp and swift increase in blood pressure that starts after the 20th week of pregnancy or, more commonly, in the last trimester (weeks 27–40). Preeclampsia can be a serious condition that may cause health complications for you and your baby.
Drugs
Blood pressure drugs typically work by removing extra fluid and salt from your body, slowing down your heartbeat, or relaxing your blood vessels. In some cases, different medications may be combined to achieve the desired effect. In addition to drugs that treat high blood pressure, some substances can cause high blood pressure.
A list of specific drugs in each class used to treat hypertension can be viewed here.
| DECREASE BP | INCREASE BP |
|---|---|
Angiotensin-converting enzyme inhibitors (ACE inhibitors) | |
Antidepressants (e.g., venlafaxine, bupropion, and desipramine) | |
Cyclosporine (Gengraf, Neoral, Sandimmune) | |
Ecstasy (aka MDMA, Molly) | |
Erythropoietin (EPO) | |
Estrogen and hormonal birth control pills | |
Nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) | |
