High blood pressure develops when the force of blood pushing against your artery walls stays elevated over time. Under the 2025 guidelines from the American Heart Association and American College of Cardiology, normal blood pressure is below 120/80 mmHg, elevated blood pressure falls between 120-129 systolic with diastolic still under 80, Stage 1 hypertension starts at 130/80, and Stage 2 begins at 140/90. Most cases have no single cause. Instead, a combination of genetics, diet, habits, and underlying conditions push your numbers up gradually.
How Blood Pressure Rises Inside Your Body
Blood pressure ultimately comes down to two things: how much blood your heart pumps and how much resistance your arteries put up against that flow. When your body retains extra sodium, blood volume increases. When your arteries narrow or stiffen, resistance climbs. Both raise the pressure reading.
Three systems play central roles. First, your kidneys regulate how much sodium and water stay in your bloodstream. When they hold onto too much, volume expands. Second, a hormonal chain called the renin-angiotensin-aldosterone system controls how tightly your blood vessels constrict and how much sodium your kidneys reabsorb. When this system is overactive, vessels tighten and fluid builds. Third, your sympathetic nervous system, the same “fight or flight” wiring that speeds your heart during stress, can become chronically ramped up, keeping your heart rate and vessel tone higher than they should be.
Genetics Set the Baseline
Family and twin studies estimate that 30 to 50 percent of the variation in blood pressure between people is inherited. That doesn’t mean half the population is destined for hypertension. It means your genes create a starting point, and everything else in this article nudges you higher or lower from there. Researchers have identified dozens of genetic variants linked to blood pressure, but collectively they explain only about 1 to 2 percent of the measurable differences in systolic and diastolic readings. The rest of the genetic contribution likely involves complex interactions between many genes and your environment that science hasn’t fully mapped yet.
What this means in practical terms: if both of your parents had high blood pressure, your risk is meaningfully higher than someone with no family history. But lifestyle factors can still move the needle substantially in either direction.
Sodium, Potassium, and the Balance That Matters
Sodium gets most of the blame, and it deserves a large share. Excess sodium pulls water into your bloodstream, expanding volume and raising pressure. The World Health Organization recommends staying under 2,000 mg of sodium per day, yet average intake in many countries far exceeds that. In the United States, about 62 percent of dietary sodium comes from store-bought packaged foods, another 26 percent from restaurant meals, and only around 12 percent from food prepared at home. That means most of the sodium you consume arrives before you ever pick up a salt shaker.
Potassium plays the counterpart role that fewer people know about. It helps your kidneys flush out sodium through urine and relaxes the smooth muscle lining your blood vessel walls, which lowers resistance. Average potassium intake sits at roughly 88 percent of the WHO recommendation, so most people are getting too much sodium and not enough potassium simultaneously. The ratio between the two may matter more than either number alone. Increasing potassium through fruits, vegetables, beans, and dairy can offset some of the pressure-raising effects of sodium, even before you cut back on processed food.
Body Weight and Physical Inactivity
Carrying excess weight forces your heart to pump harder to supply blood to more tissue, and it tends to increase sodium retention and sympathetic nervous system activity. Body mass index is one of the strongest modifiable predictors of blood pressure. Even modest weight loss, on the order of 5 to 10 percent of body weight, can produce a noticeable drop in readings.
Regular aerobic exercise lowers blood pressure through several pathways: it improves how well your blood vessels dilate, reduces sympathetic nervous system tone, and helps with weight management. A meta-analysis of randomized controlled trials found that consistent aerobic exercise reduced systolic blood pressure by about 3.8 mmHg and diastolic by about 2.6 mmHg on average. That may sound small, but at a population level those reductions significantly lower the risk of heart attack and stroke. For someone with borderline readings, that difference can be the gap between a normal result and a hypertension diagnosis.
Alcohol Intake
Alcohol raises blood pressure in a dose-dependent way, meaning the more you drink, the higher the risk climbs. A large meta-analysis of cohort studies found that above roughly 12 grams of alcohol per day (about one standard drink), hypertension risk starts increasing steadily. In women, consuming the equivalent of three drinks daily raised hypertension risk by about 38 percent compared to moderate intake, and four drinks daily raised it by 69 percent. Men showed a more linear pattern, with risk climbing at even lower thresholds. Cutting back on alcohol is one of the faster-acting lifestyle changes for blood pressure, with some people seeing improvement within weeks.
Sleep Apnea and Poor Sleep
Obstructive sleep apnea, a condition where your airway repeatedly collapses during sleep, is one of the most underrecognized contributors to high blood pressure. Each time your airway closes, oxygen drops and your body triggers a stress response that spikes blood pressure. Over months and years, this nightly cycle remodels your cardiovascular system.
The link is especially strong in people whose blood pressure doesn’t respond well to medication. In studies of patients with resistant hypertension (blood pressure that stays high despite three or more drugs), the prevalence of sleep apnea has been documented as high as 77 percent. Treating sleep apnea with a CPAP machine, which keeps the airway open at night, has been shown to produce significant reductions in both systolic and diastolic blood pressure over six months. If your blood pressure is stubbornly elevated and you snore heavily, wake up gasping, or feel exhausted despite a full night’s sleep, sleep apnea is worth investigating.
Medications and Supplements That Raise Blood Pressure
Several common drugs can push blood pressure higher, sometimes enough to tip someone from controlled to uncontrolled. Because of how widely they’re used, nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen are the most frequent culprits. They cause the kidneys to retain sodium and increase blood vessel resistance. In adults 65 and older, regular NSAID use increased the likelihood of needing blood pressure medication by 1.5 to 1.8 times depending on the dose.
Other medications and substances that can raise blood pressure include:
- Decongestants containing pseudoephedrine or phenylephrine, found in many cold and sinus products
- Certain antidepressants, particularly older classes like tricyclics and MAO inhibitors, as well as some newer serotonin-norepinephrine reuptake inhibitors
- Stimulant medications used for ADHD
- Some antipsychotic medications, particularly clozapine and olanzapine
- Sodium-containing antacids
- Herbal supplements including ephedra, St. John’s wort, and yohimbine
- Recreational stimulants such as cocaine and methamphetamine, which cause severe acute spikes
If you’re tracking high readings and take any of these regularly, that’s worth flagging to whoever manages your blood pressure.
Chronic Stress
Stress activates the sympathetic nervous system, temporarily raising heart rate and constricting blood vessels. A single stressful event won’t cause lasting hypertension, but chronic stress from work, finances, caregiving, or social isolation keeps those responses firing repeatedly. Over time, this pattern contributes to sustained elevation, particularly when stress drives other blood pressure-raising behaviors like poor sleep, overeating, increased alcohol use, and physical inactivity.
The hormonal side of chronic stress is less clear-cut than often assumed. Cortisol, the primary stress hormone, does increase how strongly blood vessels respond to constricting signals. But research has not consistently shown that elevated sympathetic nerve activity alone fully accounts for stress-related hypertension in humans. The more established pathway is indirect: stress degrades the habits that keep blood pressure in check, creating a feedback loop that’s hard to break without addressing both the stress itself and the behaviors it triggers.
Age and Other Factors You Can’t Change
Arteries stiffen naturally with age as elastic fibers in vessel walls break down and get replaced with stiffer collagen. This is why isolated systolic hypertension, where the top number is high but the bottom number is normal, becomes increasingly common after age 60. By some estimates, more than half of adults over 60 have hypertension.
Race and ethnicity also influence risk. Black adults in the United States develop hypertension earlier, at higher rates, and with more severe outcomes than other demographic groups, a disparity driven by a combination of genetic factors, social determinants of health, and differences in access to care. Men tend to develop high blood pressure earlier than women, though women’s risk rises substantially after menopause as the protective effects of estrogen on blood vessel flexibility decline.