Which effect is NOT associated with morphine?

Morphine, an opioid analgesic, is primarily known for its ability to relieve pain and is associated with several physiological effects. Among these, analgesia is the most prominent, as morphine binds to opioid receptors in the brain and spinal cord, effectively reducing the perception of pain.

Respiratory depression is a significant side effect of morphine and other opioids. It occurs because opioids can depress the central nervous system's respiratory centers, leading to slower and shallower breathing. This effect is critical to monitor, especially in clinical settings, as it can pose serious health risks.

Cough suppression is another noted effect of morphine. Opioids like morphine can act on the cough reflex threshold in the brain, thus reducing the urge to cough. This property is sometimes utilized in treating patients who need relief from severe coughing, particularly when it is not productive.

In contrast, increased respiratory rate is not associated with morphine. Typically, opioids, including morphine, lead to decreased respiratory rates due to their depressant effects on the central nervous system. Therefore, while morphine is linked to analgesia, respiratory depression, and cough suppression, it does not cause an increase in respiratory rate, making it the correct answer in this context.