Causes of High Blood Pressure

There are two possible types of high blood pressure:

primary hypertension (common)
secondary hypertension (rare)

Secondary hypertension is usually a consequence of other medical conditions.

Blood pressure

The human cardiac cycle always has two phases: systole (the pumping phase) and diastole (the filling phase). This creates systolic and diastolic pressure in the blood vessels. When the heart contracts, systolic (higher) pressure is produced. When the heart expands, diastolic (lower) pressure is produced. Blood pressure is also influenced by the large elastic arteries close to the heart and the smaller resistance vessels (organ arteries). In healthy people, the pressure resulting from increased cardiac output responds to the body's physical demands, ensuring an adequate blood supply at all times.

However, blood pressure is not constant and varies depending on the time of day. For example, it drops during sleep and is higher during the day. Blood pressure also often increases with age. Physical activity also raises blood pressure. For people with high blood pressure, this can be dangerous because exercise (especially strength training) can cause blood pressure spikes that may, in some cases, be life-threatening. Endurance activities like running, cycling, or cross-country skiing, on the other hand, have exactly the opposite effect and can lower blood pressure over the long term.

Causes of high blood pressure

Primary high blood pressure, which occurs without an underlying disease, is promoted by certain risk factors, some of which can be influenced by lifestyle. These include

excess weight and abdominal obesity
smoking
lack of physical activity
excessive alcohol
chronic stress
salt (to some extent)

Risk factors that cannot be changed include, among others

age
sex
genetics

If there is already a predisposition to high blood pressure, the modifiable risk factors are much more likely to contribute to its development.

Risk factors for developing primary hypertension

Overweight and abdominal obesity

Overweight (from a BMI of 25, obesity from 30) can increase the risk of high blood pressure because it places extra strain on the heart and its workload. But it's not just excess weight itself that is a risk factor. Because blood pressure often rises as a result of insulin resistance associated with obesity, fat distribution also matters. Pay particular attention to the belly and waist, because abdominal fat contributes to muscle, fat and liver cells responding less well to insulin. The body then needs more insulin, which increases the risk of type 2 diabetes. When overweight, high blood pressure and diabetes occur together, this is called the metabolic syndrome.

Smoking

Nicotine damages not only the coronary arteries and the arteries in the legs. It causes narrowing of all blood vessels. The harmful substances (especially free radicals) destroy the vasodilatory ability of the vessel lining (endothelium). This promotes atherosclerosis (hardening of the arteries). The resulting worsening of the blood's flow properties therefore causes a sustained rise in blood pressure.

Lack of physical activity

Lack of exercise generally weakens the body. The heart cannot work efficiently and already has to work hard during minor exertion. Physical activity can, in the long term, lower both the systolic (upper reading) and the diastolic (lower reading) values in patients with high blood pressure.

Alcohol

Large amounts of alcohol can temporarily raise blood pressure. With long-term excessive consumption, chronic high blood pressure can develop. Alcohol harms not only the heart and circulation-and thus blood pressure-but also the brain and liver.

Stress

Stress that is not relieved or overcome over a long period can raise blood pressure via the autonomic nervous system. The part known as the "sympathetic" nervous system controls vital functions such as blood pressure and circulation. It enables rapid increases in performance and therefore plays a key role in the stress response. The "parasympathetic" nervous system transmits calming signals for relaxation and stress relief. Unresolved stress can also lead to sleep problems, which also have an adverse effect on blood pressure. When stress levels are too high, the body remains under constant tension and cannot recover.

Table salt

Consuming sodium chloride, i.e. table salt, makes the smaller arteries involved in regulating blood pressure more sensitive to circulatory hormones. This can cause blood pressure to rise. The DGE (German Nutrition Society) recommends a maximum daily salt intake of 6 grams, which is approximately one teaspoon. If high blood pressure is already being treated, too much salt can make treatment more difficult, while reducing salt intake can make it easier.

Causes of secondary hypertension

The causes of secondary hypertension are usually due to an underlying disease. Common causes include metabolic disorders, kidney diseases or vascular diseases. A congenital narrowing of the main artery (aorta) can also be a cause. Hormonal medications (for example the contraceptive pill) or drugs for rheumatic disease, as well as certain illegal drugs (for example amphetamines, cocaine), are also possible causes of high blood pressure.

Special form of secondary hypertension: pregnancy-related high blood pressure

Pregnancy-related high blood pressure is a special form of secondary hypertension. It is not caused by another disease. Rather, pregnancy and the changes that come with it trigger high blood pressure. About six to eight percent of expectant mothers are affected by this form of hypertension. The risk is significantly higher for women over 40 or in multiple pregnancies. These are so-called hypertensive disorders of pregnancy (for example preeclampsia, eclampsia, HELLP syndrome), which can develop quickly and endanger mother and child. That's why blood pressure is checked regularly during pregnancy.

Sources:

This article is from Tensana – the leading app since 2011, helping hundreds of thousands of people monitor their blood pressure every day. Our content is based on carefully researched, evidence-based data and is continuously updated (as of 11/2025).

Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.