Botulinum toxin type A showed no clear difference in adverse events: dysphagia № of participants: 249 (3 RCTs) compared with botulinum toxin type B (low certainty).
Botulinum toxin type A showed no clear difference in participants with adverse events № of participants: 111 (1 RCT) compared with botulinum toxin type B (low certainty).
Botulinum toxin type A probably leads to higher adverse events: sore throat/dry mouth № of participants: 212 (2 RCTs) compared with botulinum toxin type B (moderate certainty).
Botulinum toxin type A probably leads to higher adverse events at 4 weeks; 1085 participants (8 RCTs) compared with placebo (moderate certainty).
It is very uncertain whether botulinum toxin type A changes tolerability assessed by dropouts due to adverse events compared with anticholinergics (very low certainty).
Botulinum toxin type A showed no clear difference in adverse events (reported at any time) (2 RCT, 169 participants) compared with placebo (low certainty).
Botulinum neurotoxin B leads to higher adverse events: dry mouth compared with placebo (high certainty).
Botulinum neurotoxin B leads to higher adverse events: dysphagia compared with placebo (high certainty).
It is very uncertain whether botulinum neurotoxin B changes proportion of participants with adverse events compared with placebo (very low certainty).
Botulinum neurotoxin B showed no clear difference in proportion of withdrawals due to adverse events compared with placebo (low certainty).