Botulinum toxin effective for excessive drooling

Clinical Question

Is botulinum toxin safe and effective for the treatment of sialorrhea (excessive drooling)?

Bottom Line

There is fair evidence to support botulinum toxin injections in the salivary glands for patients with excessive drooling. (LOE = 1a-)


Lim M, Mace A, Reza Nouraei SA, Sandhu G. Botulinum toxin in the management of sialorrhoea: a systematic review. Clin Otolaryngol 2006;31:267-272.  [PMID:16911641]

Study Design

Meta-analysis (randomized controlled trials)


Unknown/not stated


Outpatient (specialty)


Sialorrhea is a troublesome problem for some older patients (particularly those with Parkinson's disease, multiple system atrophy, and amyotrophic lateral sclerosis), as well as for younger patients with cerebral palsy. Injection of botulinum toxin into the salivary glands is thought to be a promising therapy. The authors searched MEDLINE, EMBASE, and other databases for clinical trials comparing botox with placebo or an alternate therapy. They identified 6 small recent studies with between 16 patients and 45 patients. Only 2 studies were double-blinded randomized placebo-controlled trials (RCTs), neither of which included any patients with cerebral palsy. The remaining 4 studies were either open-label studies (n=3), nonrandomized (n=1), or compared botulinum toxin with scopalamine (n = 1). The 2 RCTs primarily enrolled patients with chronic neurologic conditions, while the other 4 more poorly designed studies enrolled primarily patients with cerebral palsy. Patients were followed up for a maximum of between 8 weeks and 24 weeks in the 6 studies. In all of the studies there was a statistically significant benefit of botulinum toxin. One small, open-labeled study with 17 patients found a greater benefit with injection of both the submandibular and parotid glands than with submandibular gland alone, but this was much too small a study and too poor a design to give a definitive answer. The authors did not attempt to synthesize the data with a meta-analysis, presumably because of differences in study designs and outcome measures. Side effects were relatively minor, primarily dry mouth and temporary difficulty swallowing.