High blood pressure in an individual is generally asymptomatic, states the American Heart Association. Some individuals experience dizziness, blood spots in the eyes, and facial flushing, or red, hot skin of the face. Symptoms of hypertensive crisis, or a blood pressure of 180/110 or higher, include shortness of breath, nosebleeds, severe headaches and anxiety.
Other symptoms of hypertensive crisis include fatigue or confusion, vision problems, chest pain, difficulty breathing and an irregular heartbeat, reports WebMD. An individual may also feel pounding in the chest, neck or ears and have blood in the urine. Hypertensive crisis may cause a heart attack or stroke, and hypertension that goes untreated can cause heart disease, kidney and vision problems. Of the population of people with hypertension, nearly one-third are unaware of their condition.
The extent of the arteries' resistance to blood flow versus the volume of blood pumped by the heart regulates blood pressure, explains Mayo Clinic. Blood pressure increases with an increase in the amount of blood pumping in the heart and a decrease in the diameter of the arteries.
Causes of sudden high blood pressure, or secondary hypertension, include kidney problems, thyroid problems, adrenal gland tumors, some medications such as birth control and pain relievers, and alcohol abuse, according to Mayo Clinic. Causes of primary hypertension, or high blood pressure that develops gradually, has no known causes.