Benadryl Hydrochloride Tablets is a long-acting drug used for lowering blood pressure, and its effect can last for more than 24 hours. Benadryl hydrochloride tablets belong to angiotensin converting enzyme inhibitors, which can inhibit the renin-angiotensin-aldosterone system to lower blood pressure, suitable for use in all stages of hypertension, but also for congestive heart failure. Among other things, it can be used as an adjunctive therapy for patients with congestive heart failure of NYHA classification II to IV who do not respond well to digitalis and/or diuretics. The duration of the anti-hypertensive effect of the drug is usually at least 24 hours after administration, so it is a long-acting antihypertensive drug. Note that it is contraindicated in people who are allergic to the drug, and those with a history of angioneurotic edema. Common adverse reactions include palpitations, upright intolerance, flushing, headache, fainting, cough, rash, itching and so on. Specific use of the drug should be carried out under the supervision of a specialist.