Amlodipine tablets and Benadryl tablets belong to the same antihypertensive drugs, but the mechanism of action is different, the scope of application, can be applied to pregnant women are also slightly different. 1. Mechanism of action: amlodipine tablets are calcium antagonists, which can inhibit the inward flow of calcium ions in cardiac muscle and vascular smooth muscle cells, reduce the contraction strength of both, and thus reduce blood pressure; Benadryl tablets are angiotensin-converting enzymes, which can inhibit the generation of angiotensin, and thus diastole blood vessels to reduce blood pressure. 2. Scope of application: there is no strict difference, both can be used for the treatment of hypertension in all stages, but because amlodipine tablets can reduce the strength of myocardial contraction, and thus have a better effect on reducing systolic blood pressure, while Benadryl is mainly diastolic blood vessels, increase the volume of vascular content, and thus have a better effect on lowering diastolic blood pressure. 3. Can be used in pregnant women: Amlodipine tablets can be used when it is very necessary, such as pregnant women can not reduce blood pressure through lifestyle, there is a risk of eclampsia, Benadryl tablets may lead to fetal death or malformation, so pregnant women are prohibited. Selection of both need to be used under the guidance of a doctor, the people who are allergic to both can not take, the use of the process of discomfort, it is recommended to go to the hospital in a timely manner to avoid delays in the condition.