Meperidine has a higher incidence and severity of hypotension compared to morphine. Clinical studies directly comparing the two drugs have found that side effects such as histamine release, tachycardia, and hypotension were most frequent and most severe in patients who received meperidine. Morphine can also cause hypotension, but the risk and severity are generally less pronounced than with meperidine, especially regarding histamine-mediated effects.

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