Table 1.

Adverse effects of opioids [44].

S.No.	Organ system	Adverse effects
1	Respiratory system	Respiratory depression, obstructive and central sleep apnea, ataxic breathing, respiratory arrest, and death
2	Central nervous system	Increased risk of falls, cognitive impairment, myoclonus, delirium, depression, somnolence, and sleep disorders
3	Cardiovascular system	Orthostatic hypotension, bradycardia, vasodilation, and an increased risk of cardiovascular events, e.g., myocardial infarction
4	Gastrointestinal system	Constipation, nausea and vomiting, gastric reflux, delayed gastric emptying, abdominal cramping, and distension
5	Immune system	Decreased wound healing, pruritus, altered cytokine production, increased histamine release, inhibition of macrophage, neutrophil, and natural killer cell activity and recruitment, increased HIV replication, and cancer progression
6	Endocrine system	Opioid-induced endocrinopathy (usually only with high opioid doses, long-term), resulting in decreased libido, testicular atrophy, early menopause, and sexual dysfunction