Morphine is an opioid, and its side effects are mainly reflected in the following aspects: First, the respiratory system, it can inhibit the respiratory center, resulting in a slowed respiratory rate and reduced tidal volume, which can lead to respiratory arrest when the dosage is too large and the concentration is too high, and has histamine release effects, which can easily cause bronchospasm. Second, the circulatory system, morphine can lead to a decrease in peripheral vascular resistance, causing a decrease in the amount of cardiovascular blood return, resulting in hypotension, inhibition of myocardial contractility, can cause a slow heart rate. Third, the digestive system, morphine can inhibit the peristalsis of the gastrointestinal tract, causing nausea, vomiting, constipation, biliary colic. Fourth, it may also cause allergic reaction to the drug because of personal constitution, which will cause itching, urticaria, laryngeal edema, and in severe cases will lead to anaphylactic shock, which should be resuscitated immediately.