Blood pressure can be high for dozens of reasons, ranging from what you ate last night to how your arteries have changed over years. Normal blood pressure sits below 120/80 mmHg, and anything at or above 130/80 is now classified as hypertension. Roughly 1.4 billion adults worldwide have it, and only about 23% of them have it under control.
Most cases fall into a category called primary hypertension, meaning there’s no single identifiable cause. Instead, it develops from a combination of genetics, aging, diet, and lifestyle habits working together over time. A smaller but significant portion of cases are secondary hypertension, caused by a specific medical condition or medication. Experts once estimated secondary causes accounted for only 5% to 10% of cases, but newer research suggests the real number is much higher because many cases go unrecognized.
Too Much Sodium in Your Diet
Salt is one of the most well-established drivers of high blood pressure. Your kidneys filter an enormous amount of sodium every day and reabsorb more than 99% of it back into your bloodstream. When you take in more sodium than your body needs, your kidneys hold onto extra water to dilute it. That increases the volume of fluid in your blood vessels, which pushes harder against artery walls.
This process is tightly controlled by a hormone system that regulates how much sodium your kidneys retain or release. When this system is working well, your body can adjust. But when sodium intake stays chronically high, or when your kidneys lose some of their ability to excrete it efficiently, pressure stays elevated. Some people are genetically more “salt-sensitive” than others, meaning the same amount of sodium produces a bigger spike in their blood pressure. Research has identified specific genetic variants that influence how strongly your blood pressure responds to dietary salt, and this sensitivity tends to increase with age.
How Your Arteries Change With Age
Arteries aren’t passive tubes. They’re flexible, and that flexibility matters. Young, healthy arteries contain a protein called elastin that lets them stretch with each heartbeat and spring back. Over time, elastin breaks down and gets replaced by collagen, a stiffer structural protein. The ratio shifts, and arteries become more rigid.
This stiffening forces the heart to push harder to move the same volume of blood, which raises systolic pressure (the top number). Chronic inflammation, oxidative stress, and calcification all accelerate the process. High blood sugar makes it worse by promoting the production of compounds that cross-link collagen fibers, making the arterial wall even stiffer. This is one reason people with diabetes are especially prone to hypertension. Nicotine also contributes directly to arterial stiffening, even from non-combusted sources like e-cigarettes and nicotine pouches.
Nicotine and Alcohol
Nicotine raises blood pressure through several pathways at once. It activates your sympathetic nervous system, triggering the release of stress hormones like norepinephrine and epinephrine. These hormones make your heart beat faster, increase the force of each contraction, and constrict blood vessels. The result is an immediate spike in blood pressure every time you use nicotine, whether from cigarettes, vapes, or other products.
Beyond these acute effects, nicotine damages the inner lining of blood vessels over time, reducing their ability to relax and dilate. It depletes nitric oxide, a molecule your arteries rely on to stay flexible. It also promotes blood clotting and increases arterial stiffness chronically, not just during use. Heavy alcohol consumption raises blood pressure too, though the mechanisms are less precisely mapped. The combination of regular nicotine use and heavy drinking creates compounding cardiovascular strain.
Stress and the Fight-or-Flight Response
When you’re stressed, your body releases hormones that make your heart beat faster and your blood vessels narrow. This causes a steep, temporary rise in blood pressure. Once the stress passes, pressure typically returns to baseline.
There’s actually no strong evidence that stress alone causes long-term hypertension. But that doesn’t make it harmless. Repeated short spikes in blood pressure can damage blood vessels, the heart, and the kidneys over time, producing the same kind of harm as sustained high blood pressure. And stress often triggers behaviors that do raise pressure chronically: eating more sodium, drinking more alcohol, sleeping poorly, and skipping exercise.
Sleep Apnea
Obstructive sleep apnea is one of the most common and most overlooked causes of high blood pressure. When your airway collapses repeatedly during sleep, your blood oxygen drops and carbon dioxide rises. Each episode triggers a burst of sympathetic nervous system activity, flooding your body with stress hormones. These surges don’t just happen at night. The changes in nervous system activity persist into the daytime, keeping blood pressure elevated around the clock. If your blood pressure is high and resistant to treatment, or if you snore heavily and wake up tired, sleep apnea is worth investigating.
Kidney Problems
Your kidneys are central to blood pressure regulation. They control how much fluid stays in your bloodstream by adjusting sodium and water retention, all under the direction of the renin-angiotensin-aldosterone system (RAAS). When kidney function declines, this system can malfunction. The kidneys may retain too much sodium and fluid, and the hormones involved can cause blood vessels to constrict more than they should.
The relationship works in both directions. High blood pressure damages the tiny blood vessels inside the kidneys, which further impairs their ability to regulate pressure, creating a cycle that progressively worsens both conditions.
Adrenal Gland Disorders
Your adrenal glands sit on top of your kidneys and produce hormones that directly influence blood pressure. Aldosterone tells your kidneys to hold onto sodium and water, raising blood volume. Cortisol has similar effects. When the adrenal glands overproduce these hormones, blood pressure climbs and can become very difficult to control with standard treatments.
The most common adrenal cause is hyperaldosteronism, where too much aldosterone is produced. A telltale sign is high blood pressure paired with low potassium levels. This condition is more prevalent than previously thought and is a classic example of secondary hypertension that often gets misdiagnosed as primary.
Medications That Raise Blood Pressure
Several common over-the-counter medications can push your blood pressure up. Decongestants are the biggest culprits. Pseudoephedrine, phenylephrine, and oxymetazoline (found in nasal sprays) all constrict blood vessels, which is how they reduce nasal swelling but also how they raise pressure.
Nonsteroidal anti-inflammatory drugs like ibuprofen (Advil, Motrin) and naproxen (Aleve) also raise blood pressure by causing your body to retain sodium and fluid. Even the sodium content in some medications can be a factor. If you’re monitoring your blood pressure and notice unexplained increases, check whether you’ve recently started any new over-the-counter products.
What the Numbers Mean
Blood pressure readings fall into four categories:
- Normal: below 120/80 mmHg
- Elevated: 120 to 129 systolic with diastolic still below 80
- Stage 1 hypertension: 130 to 139 systolic, or 80 to 89 diastolic
- Stage 2 hypertension: 140 or higher systolic, or 90 or higher diastolic
A single high reading doesn’t necessarily mean you have hypertension. Blood pressure fluctuates throughout the day based on activity, stress, caffeine, hydration, and even the position of your arm during measurement. What matters is the pattern across multiple readings taken at different times. If your numbers consistently land in the elevated or hypertension range, the cause is worth tracking down, because the specific reason your pressure is high shapes what will actually bring it down.