High blood pressure happens when the force of blood pushing against your artery walls stays elevated over time. A normal reading falls below 120/80 mmHg, while Stage 1 hypertension starts at 130/80 and Stage 2 begins at 140/90. For most people, there isn’t one single cause. It’s a combination of how your body handles salt, how stiff your arteries have become, what medications you take, how you sleep, and what you eat and drink. Here’s a closer look at the factors most likely driving your numbers up.
How Salt Raises Your Blood Pressure
Sodium is the single most studied dietary driver of high blood pressure, and the mechanism is straightforward. When you eat more salt than your kidneys can quickly flush out, the extra sodium pulls water into your bloodstream. That increases the total volume of blood your heart has to pump, which pushes harder against artery walls. In people who are “salt-sensitive,” this volume expansion also triggers a slow rise in the resistance of smaller blood vessels, compounding the pressure increase over weeks and months.
Potassium works as sodium’s counterbalance. It signals the kidneys to release more sodium into your urine, which lowers blood volume. The recommended daily intake is 4,700 mg of potassium, but most people fall well short. When potassium is low, the kidneys hold onto even more sodium, creating a cycle that promotes salt-sensitive hypertension. Eating more potassium-rich foods (bananas, potatoes, beans, leafy greens) is one of the most reliable ways to nudge blood pressure down.
Your Arteries Stiffen With Age
Even if nothing else changes, blood pressure tends to climb as you get older. The reason is structural. Your large arteries contain elastic fibers that stretch with each heartbeat and then snap back, smoothing out the flow of blood. Over decades of nonstop pulsing, those elastic fibers break down and fragment. At the same time, stiffer collagen fibers accumulate in the artery walls. The result is a vessel that no longer absorbs the force of each heartbeat as well, so more of that force transfers directly to your blood pressure reading. This is why isolated high systolic pressure (the top number) is especially common in older adults.
Weight, Insulin, and Blood Pressure
Carrying extra weight raises blood pressure through several overlapping pathways, but one of the most important involves insulin. When your body becomes resistant to insulin, a hallmark of excess weight and prediabetes, your pancreas pumps out more of it to compensate. Insulin is a powerful signal for the kidneys to hold onto sodium. In people with insulin resistance, this sodium-retaining effect is preserved or even amplified, even as other insulin functions falter. So the kidneys reabsorb more salt, blood volume increases, and pressure rises.
Insulin resistance also activates the sympathetic nervous system (your “fight or flight” wiring) and the hormone system that constricts blood vessels. These effects layer on top of the sodium retention, making obesity one of the strongest and most common contributors to high blood pressure.
Chronic Stress and Your Nervous System
Short bursts of stress raise blood pressure temporarily, and that’s normal. The problem is when stress becomes chronic. Sustained mental stress is one of the primary triggers of long-term sympathetic nervous system activation. When that system stays dialed up, it narrows your smaller blood vessels, increasing the resistance blood meets as it flows through your body. Over time, this elevated resistance becomes the defining feature of established hypertension.
Adrenaline released during sympathetic activation also makes the heart beat harder and faster, adding to the pressure. In the early stages, blood pressure rises mainly because the heart is pumping more forcefully. Over 20 to 30 years, the pattern shifts: cardiac output returns to normal, but the blood vessels have remodeled and remain narrowed, keeping pressure high even at rest.
Sleep Apnea Is a Major Hidden Cause
If your blood pressure is high and you snore, wake up tired, or have been told you stop breathing at night, obstructive sleep apnea could be a significant factor. About 50% of people with sleep apnea have hypertension, and roughly 80% of people whose blood pressure won’t come down despite multiple medications have undiagnosed sleep apnea.
The mechanism is dramatic. Each time your airway collapses during sleep, oxygen drops and carbon dioxide spikes. Your brain responds by flooding the body with sympathetic nerve signals, constricting blood vessels and spiking pressure. This can happen dozens of times per hour. Over months and years, the repeated surges reprogram your nervous system to run at a higher baseline, keeping blood pressure elevated even during the day. Treating sleep apnea often produces a noticeable drop in blood pressure readings.
Alcohol Intake
Alcohol raises blood pressure in a dose-dependent way, meaning the more you drink, the higher the risk. A large meta-analysis found that hypertension risk climbs in a nearly linear fashion above about one standard drink per day (12 grams of alcohol). At two drinks per day, the risk is about 11% higher. At three drinks, it’s 22% higher. At four, 33% higher. In women, the association kicks in above one drink per day but rises more steeply at higher amounts compared to men. Cutting back on alcohol is one of the more effective lifestyle changes for lowering blood pressure, with results that show up within weeks.
Medications and Supplements That Raise It
Several common over-the-counter and prescription products can push blood pressure up, and many people don’t realize they’re contributing to the problem.
- Pain relievers (NSAIDs). Ibuprofen and naproxen cause the body to retain water, which increases blood volume and strains the kidneys.
- Decongestants. Pseudoephedrine and phenylephrine, found in many cold and sinus products, narrow blood vessels throughout the body, not just in the nose.
- Hormonal birth control. Pills and certain devices contain hormones that raise blood pressure in some people.
- Antidepressants. Several classes, including SSRIs, tricyclics, and MAO inhibitors, can elevate pressure by changing how the body responds to brain chemicals.
- ADHD stimulants. These speed up heart rate and can raise blood pressure as a side effect.
- Caffeine. Coffee, energy drinks, and caffeine pills can cause temporary but significant spikes, especially if you’re not a regular consumer.
- Herbal supplements. Licorice root, ginseng, guarana, and ephedra (ma-huang) are known to raise blood pressure or interfere with blood pressure medications.
Recreational drugs, particularly cocaine, methamphetamine, and ecstasy, cause dangerous spikes in blood pressure through intense sympathetic nervous system activation.
Underlying Medical Conditions
When a specific disease is driving high blood pressure, it’s called secondary hypertension. The most common culprits involve the kidneys and hormone-producing glands. Kidney diseases, including damage from diabetes, polycystic kidney disease, and inflammation of the kidney’s filtering units, all impair the organ’s ability to regulate sodium and fluid balance. Narrowing of the arteries that supply the kidneys can also trigger pressure spikes because the kidneys sense reduced blood flow and respond by retaining more salt and water.
Hormonal conditions play a role too. Overproduction of the hormone aldosterone by the adrenal glands causes the kidneys to hold onto sodium and water while flushing out potassium. A rare adrenal tumor called a pheochromocytoma floods the body with adrenaline, causing severe pressure surges. Cushing syndrome, where the body makes too much cortisol, also drives blood pressure up. These conditions are treatable, and identifying them can sometimes resolve hypertension entirely.
What Matters Most
For the vast majority of people with high blood pressure, there’s no single villain. It’s the accumulated effect of how much sodium your kidneys retain, how stiff your arteries have become, how active your sympathetic nervous system runs, and whether underlying conditions like sleep apnea or insulin resistance are quietly making things worse. The factors you can change, including salt and potassium intake, alcohol consumption, body weight, stress, sleep quality, and the medications sitting in your cabinet, are also the ones that tend to have the most meaningful impact on your numbers.