High blood pressure has two broad categories of causes. In about 90% of cases, no single identifiable condition is responsible. Instead, a combination of genetics, diet, body weight, and aging gradually pushes blood pressure upward over years. This is called primary (or essential) hypertension. The remaining cases are secondary hypertension, where a specific medical condition or medication is the direct trigger. Under current guidelines, high blood pressure starts at 130/80 mm Hg.
How Blood Pressure Gets Too High
Your blood pressure depends on two things: how hard your heart pumps and how much resistance your arteries put up against that flow. Anything that increases either one raises your numbers. In practice, the body has a built-in pressure control system centered on the kidneys. The kidneys release an enzyme called renin, which kicks off a hormonal chain reaction that tightens blood vessels and tells the kidneys to hold onto more sodium and water. When this system runs too aggressively, or when the signals telling it to calm down get weaker, blood pressure creeps up and stays up.
Your nervous system plays a role too. About 90% of the nerve connections to your kidneys are signals traveling from the brain telling the kidneys to retain sodium, release more renin, and tighten nearby blood vessels. Chronic stress, poor sleep, and obesity can all amplify these signals, keeping the system stuck in a high-pressure mode.
Salt and Fluid Retention
Excess sodium is one of the most well-established dietary causes. When you eat more salt than your body needs, the extra sodium pulls water into your bloodstream. More fluid in your blood vessels means higher pressure pushing against artery walls, much like increasing water flow through a garden hose. Over time, that extra force makes the heart work harder and can damage blood vessel walls, accelerating plaque buildup. Most adults consume well above the recommended limit of 2,300 mg of sodium per day, making this one of the most common and most fixable contributors.
Body Weight and Metabolic Changes
Carrying excess weight raises blood pressure through several pathways at once. Extra body fat physically compresses the kidneys, making it harder for them to filter sodium properly. Obesity also activates the same hormonal pressure system (renin-angiotensin-aldosterone) that the kidneys use to regulate blood volume. On top of that, fat tissue produces a hormone called leptin, which stimulates the brain to ramp up nervous system activity, further driving blood pressure higher.
People with obesity often develop insulin resistance, where cells stop responding normally to insulin. The body compensates by producing more insulin, and elevated insulin levels independently increase nervous system activity and sodium retention. These overlapping mechanisms explain why even modest weight loss, around 5 to 10% of body weight, can produce meaningful drops in blood pressure.
Alcohol Consumption
Drinking raises blood pressure in a dose-dependent way. A 2024 meta-analysis published in the journal Hypertension found that hypertension risk begins climbing noticeably above roughly one standard drink per day (about 12 grams of alcohol). Compared to that baseline, people drinking two standard drinks daily had an 11% higher risk, three drinks daily a 22% higher risk, and four drinks daily a 33% higher risk. The relationship is consistent enough that cutting back on alcohol is considered a frontline lifestyle change for managing blood pressure.
Genetics and Family History
More than 100 genetic variations have been linked to essential hypertension. Many of these involve genes that control the kidney’s pressure-regulating hormones or genes important for the health of blood vessel walls. No single gene variant causes hypertension on its own. Instead, inheriting a collection of these variants raises your baseline risk, and lifestyle factors push you over the threshold or keep you below it. If one or both of your parents have high blood pressure, your own risk is significantly higher, though it is not inevitable.
Researchers also suspect that epigenetic changes, modifications to how genes are expressed without altering the DNA itself, play a role. These changes can be influenced by diet, stress, and environmental exposures, which helps explain why hypertension runs in families through both genetic and shared lifestyle pathways.
Race, Sex, and Age
Hypertension does not affect all groups equally. CDC data from 2021 to 2023 show that 44.5% of U.S. adults have high blood pressure overall, but among Black adults the rate is 58%. This disparity likely reflects a combination of genetic predisposition, higher rates of salt sensitivity, and systemic factors like unequal access to healthcare and higher exposure to chronic stress. Among non-Hispanic Asian, White, and Hispanic adults, men consistently have higher rates than women.
Age is one of the strongest risk factors. As you get older, the large arteries lose elasticity. The flexible protein fibers in artery walls gradually stiffen, meaning they can no longer expand as easily when the heart pumps. This is why older adults often develop a pattern where the top number (systolic) rises while the bottom number (diastolic) stays the same or even drops.
Medical Conditions That Raise Blood Pressure
When a specific disease directly causes hypertension, it’s classified as secondary hypertension. Identifying and treating the underlying condition can sometimes resolve the blood pressure problem entirely. The most common causes, ranked roughly by frequency:
- Obstructive sleep apnea: Repeated pauses in breathing during sleep trigger surges of stress hormones and nervous system activation throughout the night. This is the single most common cause of secondary hypertension.
- Kidney artery narrowing: When the arteries supplying the kidneys become partially blocked, the kidneys sense reduced blood flow and respond by ramping up the hormonal system that raises blood pressure.
- Primary aldosteronism: The adrenal glands overproduce aldosterone, a hormone that tells the kidneys to retain sodium and water. This also tends to cause low potassium levels.
- Chronic kidney disease: Damaged kidneys lose the ability to properly regulate sodium and fluid balance, leading to volume overload and rising pressure.
- Thyroid disorders: Both an underactive and overactive thyroid can raise blood pressure, though they do it differently. Low thyroid function tends to raise the bottom number more, while an overactive thyroid raises the top number more.
- Cushing’s syndrome: Excess cortisol production from the adrenal glands causes high blood pressure along with weight gain in the midsection, muscle weakness, and purple stretch marks.
- Pheochromocytoma: A rare adrenal gland tumor that produces surges of adrenaline-like hormones, causing episodes of severe blood pressure spikes, headaches, sweating, and rapid heartbeat.
Medications and Substances
Several common over-the-counter and prescription drugs can raise blood pressure, sometimes without people realizing it.
- Pain relievers (NSAIDs): Ibuprofen (Advil) and naproxen (Aleve) cause the body to retain water and can raise blood pressure, especially with regular use.
- Decongestants: Ingredients like pseudoephedrine and phenylephrine, found in many cold and allergy products, work by narrowing blood vessels. That reduces nasal swelling but also increases blood pressure.
- Hormonal birth control: Pills and patches containing hormones can raise blood pressure in some people. The risk increases if you’re over 35, overweight, or smoke.
- Certain antidepressants: Several classes of antidepressants can elevate blood pressure as a side effect.
- ADHD stimulant medications: These can speed up heart rate and raise blood pressure.
- Illicit drugs: Cocaine, methamphetamine, and ecstasy all cause acute and sometimes dangerous blood pressure spikes.
If your blood pressure is difficult to control despite lifestyle changes and medication, it’s worth reviewing everything you take, including supplements and over-the-counter products, to see if something is working against you.
Physical Inactivity and Chronic Stress
A sedentary lifestyle contributes to hypertension both directly and indirectly. Regular physical activity helps keep arteries flexible, improves the body’s ability to use insulin, and reduces the overactivity of the sympathetic nervous system that drives blood pressure up. Without it, these protective effects are lost. Sedentary behavior also promotes weight gain, compounding the problem.
Chronic psychological stress keeps the nervous system in a heightened state, maintaining elevated levels of stress hormones that constrict blood vessels and increase heart rate. While a single stressful event causes a temporary spike, ongoing stress from work, financial pressure, or discrimination can contribute to sustained elevations over months and years. Stress also tends to worsen other risk factors by encouraging poor sleep, overeating, higher alcohol intake, and less physical activity.