The Effects of Morphine on the Cardiovascular System

Morphine, an opiate, is useful in the treatment of cardiac ailments, according to the University of California School of Medicine. Nonetheless, there are various effects to the cardiovascular system resulting from morphine treatments. While some of these effects are benign and others effectively aid in treatment and anesthesia, there are known risks and complications to the cardiovascular system associated with morphine that can prove dangerous.

Morphine is an opiate often administered intravenously. (Image: Kati Neudert/iStock/Getty Images)


According to the book "Clinical Anesthesia," typical doses of morphine have little effect on blood pressure or pulse. Alternately, higher doses of morphine can result in vasodilation, which is an expansion of blood vessels due to weakening smooth muscle surrounding them. This can result in a number of problems, including complications to the respiratory system, cardiovascular system and nervous system.

Cerebral Circulation

Respiratory depression and hypotension associated with morphine can affect cerebral circulation, according to the book "Clinical Anesthesia." This can result in cerebral vasodilation and increases in cerebral and spinal fluid pressure. Because of this characteristic, doctors administering morphine to patients with head trauma must exercise extreme care.


In addition to vasodilation, morphine can reduce baroreceptor reflexes; together, both effects can cause low blood pressure, or hypotension. Hypotension can trigger fainting spells as well as seizures.

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