Hypersalivation or hypersialosis is the excessive production of saliva. It has also been defined as increased amount of saliva in the mouth, which may also be caused by decreased clearance of saliva. Hypersalivation can contribute to drooling if there is an inability to keep the mouth closed or difficulty in swallowing (dysphagia) the excess saliva, which can lead to excessive spitting. Hypersalivation also often precedes emesis (vomiting), where it accompanies nausea (a feeling of needing to vomit)..