🔍 Hypertension Causes & Risk Factors: Why Do You Get High Blood Pressure?

For most people, hypertension doesn’t have a single, obvious cause. It’s the result of a complex interplay between the genes you inherited and the environment you live in — your diet, your activity level, your stress, and even the air you breathe. Understanding your personal risk factors is the first step toward taking control. Dr. Ravi Sishir Reddy explains the known causes of high blood pressure, the factors you can’t change, and — most importantly — the ones you can.

1. Primary (Essential) Hypertension: A Multifactorial Puzzle

About 90–95% of adults with high blood pressure have primary hypertension — meaning there’s no single identifiable cause. Instead, it’s a gradual process driven by a collection of genetic, dietary, and lifestyle factors that accumulate over decades.

In primary hypertension, the body’s normal blood pressure regulation systems gradually shift. The renin‑angiotensin‑aldosterone system may become overactive; the sympathetic nervous system may stay in “fight‑or‑flight” mode; the kidneys may retain too much sodium; and blood vessels may lose their flexibility. These changes don’t happen overnight, but they accelerate when risk factors are present.

2. Risk Factors You Cannot Change

• Age: Blood pressure naturally rises as arteries stiffen. The risk of hypertension increases significantly after age 45 in men and after 55 in women.
• Family history: Hypertension runs in families. If one or both parents have high blood pressure, your risk is substantially higher.
• Ethnicity: People of South Asian, African, and African‑Caribbean descent tend to develop hypertension earlier and with greater severity. The reasons are partly genetic and partly environmental.
• Gender: Before menopause, women generally have lower blood pressure than men of the same age. After menopause, the protective effect of oestrogen fades, and a woman’s risk catches up — and sometimes surpasses — that of men.
• Certain genetic conditions: Rare single‑gene disorders (like Liddle’s syndrome) cause severe hypertension at a young age.

3. Risk Factors You Can Control

• Obesity and overweight: Excess body weight increases blood volume, puts strain on the heart, and is linked to insulin resistance and inflammation. Even a 5‑10% weight loss can significantly reduce blood pressure.
• High salt (sodium) intake: Sodium causes the body to retain fluid, increasing blood volume and pressure. Some individuals are “salt‑sensitive” — their BP rises sharply with excess salt. Processed foods, pickles, papads, and restaurant meals are major hidden salt sources.
• Low potassium intake: Potassium helps balance sodium and relax blood vessel walls. A diet low in fruits and vegetables (rich potassium sources) is a risk factor.
• Physical inactivity: A sedentary lifestyle leads to weight gain, arterial stiffness, and a higher resting heart rate. Regular aerobic exercise lowers both systolic and diastolic pressure by 4‑8 mmHg.
• Excessive alcohol consumption: More than one drink per day for women or two for men raises BP. Binge drinking causes sharp spikes.
• Smoking and tobacco use: Nicotine constricts blood vessels and hardens arteries. Each cigarette causes a temporary BP spike, and long‑term smoking leads to permanent vascular damage.
• Chronic stress: Constant activation of the stress response raises cortisol and adrenaline, which over time increase baseline blood pressure. Job strain, caregiving burdens, and financial issues are common contributors.
• Poor sleep and sleep apnea: Obstructive sleep apnea (OSA) causes repeated nighttime drops in oxygen, triggering sympathetic surges that persist during the day. Insomnia and short sleep duration are independently linked to hypertension.

4. Secondary Hypertension: When an Underlying Condition Raises Your BP

In about 5‑10% of cases, hypertension has a specific, treatable underlying cause. Secondary hypertension should be suspected when BP arises suddenly, is severe, or is resistant to standard medications. Common causes include:

• Kidney disease: Chronic kidney disease, renal artery stenosis, polycystic kidney disease — all impair the kidneys' ability to regulate fluid and electrolytes.
• Adrenal gland tumours: Pheochromocytoma (excess adrenaline), primary aldosteronism (Conn’s syndrome), Cushing’s syndrome — overproduce hormones that raise BP.
• Thyroid disease: Hyperthyroidism increases systolic pressure; hypothyroidism raises diastolic pressure.
• Coarctation of the aorta: A congenital narrowing of the aorta that forces the heart to pump harder.
• Medications: Decongestants, NSAIDs (ibuprofen, naproxen), oral contraceptives, corticosteroids, some antidepressants, and certain weight‑loss drugs can raise BP.
• Obstructive sleep apnea: Already mentioned as a modifiable factor, but when severe, it’s a distinct secondary cause.
• Pregnancy: As discussed in a separate article, gestational hypertension and preeclampsia are unique to pregnancy.

If secondary hypertension is identified, treating the underlying condition may normalise blood pressure entirely.

👉 Read more: Primary vs. Secondary Hypertension →

5. How to Think About Your Own Risk

Dr. Reddy suggests looking at your risk factors as a whole, not in isolation. For example, a 55‑year‑old with a strong family history and a BMI of 32 has a much higher risk than a 30‑year‑old with only one modifiable factor. Tools like the Framingham Risk Score or QRISK are used by doctors to estimate cardiovascular risk, but the most practical step you can take today is to buy a home BP monitor and start tracking your numbers.