| Botulinum neurotoxin (N = 20) | Tizanidine (N = 21) | Placebo (N = 19) | |
| Subjects experiencing ⩾1 AE possibly related to treatment—no (%) | 8 (40.0)* | 19 (90.5) | 10 (52.6) |
| Most common | |||
| Somnolence | 4 (20.0) | 10 (47.6) | 2 (10.5) |
| Tiredness/fatigue | 4 (20.0) | 2 (9.5) | 2 (10.5) |
| Headache | 2 (10.0) | 2 (9.5) | 0 (0.0) |
| Oedema | 0 (0.0) | 1 (4.8) | 2 (10.5) |
| Dizziness | 0 (0.0) | 3 (14.2) | 0 (0.0) |
| Nausea/stomach ache | 0 (0.0) | 3 (14.2) | 0 (0.0) |
| Depression | 1 (5.0) | 0 (0.0) | 1 (5.2) |
| Rash | 1 (5.0) | 0 (0.0) | 1 (5.2) |
| Asthenia | 1 (5.0) | 0 (0.0) | 1 (5.2) |
| Fall | 1 (5.0) | 1 (4.8) | 0 (0.0) |
| Elevated liver enzyme | 0 (0.0) | 2 (9.5) | 0 (0.0) |
*p = 0.0007 versus tizanidine; p = 0.4290 versus placebo (χ2); p = 0.0074 versus placebo (χ2).