What is a common adverse effect of morphine?

Morphine is an opioid analgesic commonly used to manage severe pain. One of its notable adverse effects is urinary retention. This occurs because morphine and other opioids can affect the autonomic nervous system, leading to increased tone in the sphincters of the bladder, which can inhibit the normal urge to urinate and inhibit bladder contractions.

Patients may feel a sensation of fullness in their bladder without being able to void, leading to discomfort and potential complications if it becomes severe or prolonged. Recognizing urinary retention as a side effect is critical in clinical practice, ensuring that appropriate measures are taken to manage this condition if it occurs.

In contrast, other options like increased heart rate, blood thinning, and muscle cramps are not commonly associated with morphine. Increased heart rate is more often a response to pain or anxiety rather than a direct effect of morphine. Blood thinning is not a recognized side effect of morphine; instead, opioid medications do not have anti-coagulant properties. Finally, while muscle cramps can occur for a variety of reasons, they are not a typical side effect of morphine specifically.