Diphenhydramine tablets generally refer to calcium antagonist antihypertensive drugs and are recommended to be taken on an empty stomach before meals. Diphenhydramine tablets generally refer to calcium antagonist antihypertensive drugs such as amlodipine, nifedipine, nitrendipine and so on. When taken on an empty stomach before meals, the gastrointestinal tract is able to rapidly decompose and absorb the components of these antihypertensive drugs, so that the antihypertensive effect can be quickly exerted. After meals, the gastrointestinal tract needs to digest food, the absorption of the drug is weakened, resulting in the effect of antihypertensive drugs to play slowly, so that the blood pressure control effect is not good. Calcium ion antagonist antihypertensive drugs mainly through the dilation of arterial smooth muscle, reduce peripheral resistance, so as to play a role in lowering blood pressure. The main adverse effects of this class of drugs include hypotension, tachycardia, headache, anterior tibial and ankle edema. It is contraindicated in patients who are allergic to the components of the drug. Specific drug use and precautions need to consult a professional physician, do not use drugs without authorization to avoid adverse reactions.