Meta-analysis for harms by category
| Harms | Intervention | Comparator | Studies | N | Random effects—RR (95% CI) | I2 (%) |
| Cardiorespiratory system disorders | ||||||
| Heart palpitations | Opioid | Non-opioid | 2 | 430 | 2.72 (0.73 to 10.15) | 0 |
| Nasopharyngitis | Opioid | Placebo | 1 | 205 | 0.76 (0.21 to 2.76) | – |
| Sinusitis | Opioid | Placebo | 1 | 302 | 0.75 (0.17 to 3.29) | – |
| Upper respiratory infection | Opioid | Placebo | 1 | 205 | 0.16 (0.02 to 1.30) | – |
| Dermatology system disorders | ||||||
| Pruritus | Opioid | Placebo | 7 | 2245 | 2.68 (1.21 to 5.97) | 66 |
| Gastrointestinal system disorders | ||||||
| Constipation | Opioid | Placebo | 11 | 3639 | 2.40 (1.48 to 3.89) | 68 |
| Constipation | Opioid | Non-opioid | 3 | 665 | 2.24 (0.97 to 5.20) | 0 |
| Diarrhoea | Opioid | Placebo | 5 | 2059 | 0.62 (0.42 to 0.90) | 0 |
| Dyspepsia | Opioid | Placebo | 3 | 1520 | 1.43 (0.66 to 3.11) | 25 |
| Dyspepsia | Opioid | Non-opioid | 2 | 1026 | 1.33 (0.23 to 7.60) | 12 |
| Nausea | Opioid | Placebo | 11 | 3639 | 1.84 (1.21 to 2.81) | 77 |
| Nausea | Opioid | Non-opioid | 4 | 1456 | 1.62 (0.28 to 0.19) | 91 |
| Vomiting | Opioid | Placebo | 9 | 3003 | 1.99 (1.10 to 3.62) | 51 |
| Vomiting | Opioid | Non-opioid | 3 | 1221 | 5.53 (1.85 to 16.55) | 31 |
| Genitourinary system disorders | ||||||
| Erectile dysfunction | Opioid | Placebo | 1 | 103 | 3.43 (0.14 to 82.25) | – |
| Urinary tract infection | Opioid | Placebo | 1 | 302 | 2.67 (0.72 to 9.86) | – |
| Musculoskeletal system disorders | ||||||
| Arthralgia | Opioid | Placebo | 1 | 268 | 2.67 (0.72 to 9.83) | – |
| Back pain | Opioid | Placebo | 3 | 712 | 1.01 (0.51 to 1.99) | 0 |
| Nervous system disorders | ||||||
| Diaphoresis | Opioid | Placebo | 2 | 1284 | 29.24 (4.00 to 213.99) | 0 |
| Diaphoresis | Opioid | Non-opioid | 2 | 430 | 1.70 (0.41 to 7.05) | 0 |
| Dizziness/vertigo | Opioid | Placebo | 8 | 3126 | 1.52 (0.91 to 2.55) | 71 |
| Dizziness/vertigo | Opioid | Non-opioid | 4 | 1456 | 2.77 (1.40 to 5.49) | 62 |
| Dry mouth | Opioid | Placebo | 3 | 1387 | 2.27 (1.00 to 5.15) | 33 |
| Fatigue | Opioid | Placebo | 6 | 2333 | 1.61 (1.11 to 2.34) | 0 |
| Fatigue | Opioid | Non-opioid | 3 | 665 | 1.26 (0.59 to 2.67) | 0 |
| Headaches | Opioid | Placebo | 11 | 3790 | 1.15 (0.85 to 1.56) | 34 |
| Headaches | Opioid | Non-opioid | 2 | 455 | 4.39 (0.75 to 25.68) | 0 |
| Hypoacusis | Opioid | Placebo | 1 | 302 | 1.25 (0.34 to 4.57) | – |
| Insomnia | Opioid | Placebo | 6 | 2365 | 1.46 (0.90 to 2.38) | 32 |
| Sedation | Opioid | Placebo | 2 | 258 | 1.18 (0.63 to 2.21) | 82 |
| Somnolence | Opioid | Placebo | 9 | 3300 | 2.25 (1.01 to 5.01) | 74 |
| Somnolence | Opioid | Non-opioid | 2 | 1011 | 1.33 (0.32 to 5.54) | 55 |
| Withdrawal syndrome | ||||||
| Opioid | Placebo | 4 | 917 | 0.36 (0.11 to 1.21) | 45 | |