The maximum dose of Benadryl Hydrochloride Tablets to be taken in a day is not more than 40mg. due to different sizes, for example 5mg/tablet, not more than 8 tablets. Generally patients do not need the maximum dose and need to be applied under doctor’s supervision. The main ingredient of Benadryl Hydrochloride Tablets is Benadryl Hydrochloride, which belongs to the angiotensin-converting enzyme inhibiting class of prescription drugs. It is mainly used for the treatment of hypertension and congestive heart failure. The dosage varies between 2.5mg/day and 40mg/day due to the type of the patient’s disease, creatinine clearance, severity of the disease, and response to the drug. Usually, the dosage for treating heart failure is roughly between 2.5mg/day~20mg/day, while the dosage for treating hypertension is roughly between 10mg/day~40mg/day. If you experience any discomfort while taking Benadryl Hydrochloride Tablets, you need to seek medical advice promptly. The main adverse reactions of Benadryl Hydrochloride Tablets are rash, cough, postural vertigo and headache. Benadryl hydrochloride tablets are contraindicated for those who have previously experienced angioneurotic edema and those who are allergic to the product. The dosage of the drug should be adjusted under the supervision of a physician.