Pain can stimulate sympathetic nerves causing increased myocardial contraction and vasoconstriction leading to increased blood pressure. Pain causes excitation of the renin-angiotensin system, which releases angiotensin leading to vasoconstriction and increased heart rate causing increased blood pressure. Activation of the renin-angiotensin system causes increased aldosterone, leading to water and sodium retention causing increased blood pressure. Clinically, pain can lead to increased blood pressure. Common causes such as abdominal pain, pain caused by lumbar disc herniation, and pain caused by femoral neck fracture can lead to increased blood pressure, and blood pressure will return to normal after pain relief.