In the 19th and 20th centuries, before effective pharmacological treatment for hypertension became possible, three treatment modalities were used, all with numerous side-effects: strict sodium restriction (for example the rice diet[152]), sympathectomy (surgical ablation of parts of the sympathetic nervous system), and pyrogen therapy (injection of substances that caused a fever, indirectly reducing blood pressure).[152][158]
^ Jump up to: a b c Members, Authors/Task Force; Mancia, Giuseppe; Fagard, Robert; Narkiewicz, Krzysztof; Redon, Josep; Zanchetti, Alberto; Böhm, Michael; Christiaens, Thierry; Cifkova, Renata (13 June 2013). "2013 ESH/ESC Guidelines for the management of arterial hypertension". European Heart Journal. 34 (28): 2159–219. doi:10.1093/eurheartj/eht151. hdl:1854/LU-4127523. ISSN 0195-668X. PMID 23771844. Archived from the original on 27 January 2015.
According to guidelines from the American Heart Association (AHA) and the American College of Cardiology (ACC), a reading below 120/80 mm Hg is classified as normal blood pressure. Those with a blood pressure reading anywhere from 120/80 up to 129/80 are classified within a category called elevated blood pressure. Hypertension is defined as a reading of 130/80 or higher.

During relaxation of the heart (diastole), the left ventricle of the heart fills with blood returning from the lungs. The left ventricle then contracts and pumps blood into the arteries (systole). The blood pressure in the arteries during contraction of the ventricle (systolic pressure) is higher because blood is being actively ejected into the arteries. It is lower during relaxation of the ventricle (diastolic pressure) when no blood is being ejected into the arteries. The pulse we feel when we place our fingers over an artery is caused by the contraction of the left ventricle and the ejection of blood.

^ Jump up to: a b c d e f Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo Jr. JL, Jones DW, Materson BJ, Oparil S, Wright Jr. JT, Roccella EJ, et al. (December 2003). "Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure". Hypertension. Joint National Committee On Prevention. 42 (6): 1206–52. doi:10.1161/01.HYP.0000107251.49515.c2. PMID 14656957. Archived from the original on 20 May 2012. Retrieved 1 January 2012.
Hypertension, the medical term for high blood pressure, is known as "the silent killer." More than 80 million Americans (33%) have high blood pressure, and as many as 16 million of them do not even know they have the condition. If left untreated, high blood pressure greatly increases your risk for heart attack and stroke. Hypertension is projected to increase about 8 percent between 2013 and 2030. 

Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
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