Secondary hypertension is more likely to cause damage to the heart, brain, kidney and other important target organs because patients usually have big fluctuation of blood pressure, various primary diseases and big difficulty in treatment, so secondary hypertension is more dangerous. 1. Large fluctuation of blood pressure: patients with ordinary hypertension are usually in a relatively stable state, while patients with secondary hypertension usually have the symptoms of sudden increase and decrease of blood pressure, large fluctuation of blood pressure and general antihypertensive drugs can not play an obvious effect. 2. Various primary diseases: there are many kinds of diseases that cause secondary hypertension, such as common primary aldehydes, Cushing’s syndrome, aortic constriction and so on, all of which can induce secondary hypertension. And these primary diseases can have serious consequences if not treated in time. 3. Difficulty in treatment: As the cause of secondary hypertension is very complicated, patients will have other symptoms besides hypertension, and the treatment not only needs to control the patient’s blood pressure but also needs to treat the primary disease at the same time, so the treatment is more difficult. Secondary hypertension usually develops at an earlier age, and serious target organ damage occurs at an earlier age. Therefore, if patients find dizziness and headache, or if their blood pressure increases, they must go to the hospital in time to get a clear picture of the cause of the disease, and then follow the doctor’s instructions to choose the targeted treatment.