Five Main Reasons for Blood Pressure - Health Facts 1. High Blood pressure(hypertension) is caused by high levels of salt in the body. Salt causes water retention in the body, which increases blood volume and forces blood vessels to constrict. When the heart pumps out blood, it pushes on the arteries, causing them to narrow. As a result, the amount of blood pumped out decreased. 2. Stress and anxiety cause the sympathetic nervous system to release adrenaline, which raises blood pressure. Adrenaline signals the adrenal glands to produce cortisol, which causes the liver to store sodium. Cortisol also causes the kidneys to retain water, which makes the blood thicker. 3. Smoking marijuana may increase blood pressure. Marijuana contains chemicals called cannabinoids, including THC, which activate cannabinoid receptors in the brain. These receptors regulate blood pressure. 4. A Diet rich in saturated fats and cholesterol can raise blood pressure. Saturated fats