Table 1.

Organ system effects of morphine and its surrogates. The actions summarized in this table are observed for all clinically available opioid agonists

Organ Systems	Effects	Additional information
Central Nervous system	↑ Analgesia
	↑ Euphoria	leading to risk of addiction and abuse
	↑Sedation
	↓ Rate of respiration
	↓ Cough reflex	Codeine used for treatment of pathological cough
	↑ Miosis-Constriction of the pupils
	↑ Truncal rigidity	Most apparent when using fentanyl, sufentanil, alfentanil
	↑ Nausea and vomiting
Peripheral	Gastrointestinal system
	↑ Constipation
	↓ Gastric motility
	↓ Digestion in the small intestine
	↓ Peristaltic waves in the colon
	↑ Constriction of biliary smooth muscle
	↑ Esophageal reflux
	Other smooth muscle
	↑ Depression of renal function
	↓ Uterine tone
	↑ Urinary retention
	Skin
	↑ Itching and sweating
	↑ Flushing of the face, neck and thorax
	Cardiovascular system
	↓ Blood pressure and heart rate if cardiovascular system is stressed
	Immune System
	↓ Formation of rosettes by human lymphocytes
	↓ Cytotoxic activity of natural killer cells
	Other
	Behavioral restlessness