Table 6 Prescribed opioids and the incidence of somnolence and dizziness
Concomitant use of opioid with pregabalin | N | Developed somnolence | Developed dizziness |
 Non-prescribed patients | 141 | 28 (19.9 %) | 21 (14.9 %) |
 Prescribed patients | 54 | 19 (35.2 %) | 13 (24.1 %) |
Concomitant opioids | N | Developed somnolence or dizziness | |
 Fentanyl | 26 | 7 (26.9 %) | |
 Oxycodone | 23 | 11 (47.8 %) | |
 Tramadol | 18 | 7 (38.9 %) | |
 Morphine | 4 | 0 (0 %) | |