Common adverse reactions to Benadryl hydrochloride are hypotension, malaise, headache, palpitations (rapid heartbeat, often accompanied by panic), gastrointestinal disturbances, and flushing of the skin. Benadryl hydrochloride is mainly used to treat hypertension and congestive heart failure. This drug is generally well tolerated, and if adverse reactions occur, they are generally cardiovascular adverse reactions, such as palpitations and symptoms of upright intolerance; respiratory adverse reactions, such as cough and symptoms of upper respiratory tract infection; gastrointestinal adverse reactions, such as gastrointestinal disorders; and systemic discomfort, such as fatigue. This drug needs to be taken under the guidance of a doctor, do not take at will, increase or decrease the amount and discontinue perhaps listen to the doctor’s advice, the emergence of adverse reactions to the doctor, consult a doctor in a timely manner.