Why am I drooling over

When your mouth is watering too much


By Daniela Biermann


Increased salivation can have many causes; it occurs, for example, as a side effect of some drugs. Read the following article about what can cause sialorrhea and how it is treated.


Even if it sounds harmless at first: An excessively increased salivation (sialorrhea, hypersalivation or ptyalism) is a disease to be taken seriously, as it is very stressful for those affected. Because the environment often negatively perceives sialorrhea as "wet pronunciation" or "drooling". In addition to social exclusion, it can lead to medical problems. Skin infections, coughing, choking and vomiting are possible. If saliva gets into the respiratory tract, the risk of respiratory infections and pneumonia also increases.


A healthy adult produces 0.7 to 1.5 liters of saliva every day. This consists of 99.5 percent water. The majority, around 90 percent, comes from the three large paired head salivary glands: parotid gland (glandula parotis), lower jaw gland (glandula submandibularis) and sublingual gland (glandula sublingualis). Depending on whether the parasympathetic or sympathetic nervous system modulates saliva production more strongly, the secretion is more watery or more viscous.


Saliva contains proteins such as α-amylase, polysaccharide mixtures such as mucin, electrolytes, bactericides and antibodies, especially immunoglobulin A. The function of saliva is explained by its composition: it moisturizes the mucous membranes, contributes to the immune system, and absorbs soluble substances from food mixes with dry ingredients so that the food pulp is easier to swallow. The breakdown of carbohydrates already begins in the mouth by α-amylases. The electrolytes are important for the remineralization of the teeth. Too little saliva promotes the development of caries.


One symptom, many causes


Sialorrhea occurs when production is increased and the saliva can only insufficiently drain off. Increased salivation is normal up to the age of four. During pregnancy, due to an increased parasympathetic effect, so-called ptyalism gravidarum can occur, especially in the second to fourth month. Acidic foods, appetite stimulating stimuli, excitement, nausea and foreign bodies in the throat can physiologically increase the amount of secretion for a short time.


The causes of pathologically increased salivation are diverse and are divided into local factors, general diseases, neurological disorders and drug factors. Increased salivation is part of the clinical picture of diabetes insipidus, in which large amounts of fluid are excreted, of myasthenia gravis, an autoimmune disease with a disorder of neuromuscular stimulus transmission, or the vitamin deficiency disease pellagra. A locally caused sialorrhea occurs, for example, with tooth decay, inflammation of the oral mucosa and tonsils, or a faulty tooth position.


Sialorrhea is often related to neurological diseases. Central nervous examples are Parkinson's disease and amyotrophic lateral sclerosis. In the periphery, disorders of the facial and trigeminal nerves can disrupt the flow of saliva. In most cases, neurological symptoms do not increase production, rather the outflow is impeded by swallowing disorders or decreased swallowing frequencies. Hypersalivation also occurs in psychiatric illnesses such as schizophrenia and manic depression.


Typical symptoms of poisoning


Increased salivation can occur as a side effect of some medications and as a symptom of intoxication. Parasympathomimetics such as carbachol and pilocarpine stimulate saliva production via muscarinic receptors. Pilocarpine is even used medicinally for this purpose. The subtype M is particularly important for the salivary glands3 significant. Cholinesterase blockers such as physostigmine, neostigmine and organophosphates also have an indirect parasympathomimetic effect by preventing the breakdown of the neurotransmitter acetylcholine at the muscarinic synapses. Conversely, it is understandable that sympatholytics have a similar effect.


Neuroleptics also play an important role. A third to a half of the patients treated with clozapine suffer from sialorrhea. Presumably the atypical neuroleptic acts as an agonist on M.4-Receptors also found in exocrine glands. It also stimulates adrenergic α as an antagonist1- and α2Receptors. As a result, blood flow increases and with it the production of saliva.


Sialorrhea has been described as a side effect for numerous other pharmacological substances. Examples are mucosa-irritating antibiotics, cardiac glycosides, caffeine and nicotine, quinine, theophylline, reserpine, clonazepam, morphine and apomorphine, mercury and thallium.


Parasympathetic attack


Treatment should first try to eliminate the cause or underlying disease. For example, misaligned teeth can be corrected or the tonsils can be removed. If this does not work, drugs can help reduce saliva production. No drug is currently explicitly approved for the treatment of sialorrhea. However, clinical studies with mostly smaller patient groups have shown the benefit of some drugs. Above all, the anticholinergic effect of parasympatholytics is used. Muscarinic receptor antagonists such as scopolamine or atropine significantly reduce saliva production. The main contraindications include glaucoma and benign prostatic hyperplasia. Typical side effects are constipation, reddening of the skin, dilated pupils, urine retention and confusion.


Scopolamine is put on as a plaster directly behind the ear, as this is where the drug is best permeable. A patch can be worn for up to four days. The flow of saliva is effectively inhibited. So far, no data are available for long-term therapy.


Atropine has been successfully used sublingually in the form of drops or tablets in studies. Quaternary atropine and scopolamine derivatives are also used. For example, glycopyrronium bromide is also available as a tablet in the United States. In a recently published study, the use of a sublingual ipratropium bromide spray did not significantly reduce the amount of saliva in 17 Parkinson's patients, but it did provide subjective relief. Tertiary anticholinergics such as Trihexyphenidyl and Biperiden are used in Parkinson's disease and improve muscle stiffness and dystonia as well as sialorrhea.


The use of botulinum toxin is also moving more and more into focus. The neurotoxin inhibits the release of acetylcholine into the synaptic cleft. To do this, it is injected directly into the ear and mandibular salivary glands. The studies describe the application as safe and well tolerated. However, further data, for example on the optimal injection site and duration of action, are currently lacking. In clozapine-induced hypersalivation, the combination with antidepressants such as amisulpride or sulpiride can bring relief, as several double-blind, placebo-controlled studies have shown. Another approach is the administration of clonidine, in which dry mouth was observed as a side effect. As the central α2-Agonist it is supposed to lower the sympathetic tone and thus the blood circulation.


In addition to drug therapy, radiation therapy, acupuncture, behavior modification, speech therapy, physiotherapy and, ultimately, surgical measures are available.