Dry mouth management: clinical perils for pharmacists

Case scenario

Lakshmi, a 58-year-old female, presents to the pharmacy complaining of a sticky feeling in her mouth. She says family members have commented that her breath smells, despite brushing and flossing regularly. She also mentions that she is very thirsty and drinking more water than usual, but this doesn’t seem to help her symptoms. Lakshmi adds that this all started only a few weeks ago. You review her medicines history and notice that she recently started duloxetine for major depression. Lakshmi asks for advice on how to alleviate her symptoms.

Introduction 

Dry mouth (or xerostomia) is described as the subjective sensation of dryness in the oral cavity.¹ This can be a potential consequence of a reduced salivary flow (hyposalivation), however individuals can also present with xerostomia and have normal salivary flow. Dry mouth is a common condition that can harm dentition, contribute to mucosal discomfort and affect an individual’s quality of life.^2,3 In Australia, more than 10% of people experience dry mouth.⁴ Among older Australians, the estimate is greater, with approximately 25% experiencing xerostomia.⁴ In the older population, polypharmacy plays a dose-dependent role. Pharmacists are the health professionals who are most seen by the community, therefore pharmacists can significantly contribute to promoting excellence in oral health.⁵ In addition, the provision of oral health care by pharmacists has been positively accepted by patients.⁶ This article will describe the clinical perils of dry mouth management and hyposalivation.

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Epidemiology

According to a systematic review to estimate the overall prevalence of xerostomia/hyposalivation in epidemiological studies worldwide, the estimated prevalence of dry mouth was 22.0% (95% CI 17.0–26.0%).⁷ According to a systematic review of a nationally representative sample of Australian adults, the prevalence of dry mouth was 13.2% (95% CI 12.4, 14.0)⁴ and was more common in older people. If stratified, among a 15–34-year- old age group, the prevalence was 9.3% (95% CI 7.9, 10.8); among 35–54-year-olds the prevalence was 11.0% (95% CI 9.7, 12.3), and was 17.6% in 55–74-year-olds (95%CI 16.2, 19.1), and 26.5% (95% CI 23.3, 30.0) among those aged 75 or older. This data was derived from Australia’s National Survey of Adult Oral Health 2017–18.⁴

Aetiology and pathophysiology

Saliva is important for the maintenance of optimal oral health. It is one of nature’s oral environmental defence systems and consists of a mixture of water, electrolytes, and organic micromolecules and macromolecules. Saliva also contains calcium and phosphate required for dental remineralisation.⁸ Its secretion is regulated by reflexes involving the autonomic nervous system.

On an anatomical level, there are three major salivary glands present inside the oral cavity (see also Figure 1):

• parotid gland (predominately serous acini secreting a serous α-amylase-rich saliva)
• sublingual gland (predominately mucous acini secreting a viscous solution rich in mucins)
• submandibular gland (a mixed saliva from acini with a mucous and serous function).

These major salivary glands are responsible for more than 90% of salivary secretion.⁹ There are minor salivary glands that are also present throughout the mucosa of the oral cavity, such as the floor of the mouth, palate, inner lining of the lips (labial mucosa) and mucous membrane of the tongue (lingual mucosa). Impairment of salivary glands and reduction in salivary flow can lead to dry mouth. This can be due to a congenital absence of salivary glands or developmental anomaly (agenesis/aplasia). It can also be secondary to other conditions. Possible causes include^10,11:

• head and neck radiotherapy
• Dehydration
• Sjögren’s syndrome
• chronic inflammation/autoimmune inflammatory disease (e.g. oral lichen planus, rheumatoid arthritis, sarcoidosis)
• endocrine conditions (e.g. diabetes mellitus, hypothyroidism)
• neurological disease (e.g. Parkinson’s disease)
• psychological disorders (e.g. anxiety)
• metabolic disorders (e.g. eating disorders, alcohol intake, chronic renal failure)
• infectious diseases (e.g. human immunodeficiency virus, hepatitis C).

Mouth breathing and some types of medicines can also lead to symptoms of dry mouth.

For people with chronic dry mouth, medicines pose the most important risk factor.⁷ Medicines that tend to cause dry mouth are considered xerogenic. Xerogenic medicines with documented evidence are medicines with anticholinergic activity. These include medicines for urinary incontinence, antidepressants, antipsychotics and antihistamines, as well as antihypertensives, diuretics, bronchodilators, and opioids. The occurrence of dry mouth increases as the number of medicines a person takes increases.^10,12

It is important to note that there are many factors which could be contributing to xerostomia. For example, individuals with rheumatoid arthritis have an increased predisposition to Sjögren’s syndrome which can contribute to xerostomia.¹³

Clinical features and diagnosis 

Symptoms of dry mouth can include but are not limited to¹⁴: 

• a sensation of oral dryness
• oral burning or soreness
• dysgeusia (taste disturbance)
• polydipsia (excessive thirst)
• dysphagia (difficulty swallowing)
• dysphonia (hoarseness of voice)
• thickened saliva sensation or frothy saliva 
• halitosis.

Dry mouth significantly impacts oral health and quality of life. As a result of chronic salivary gland hypofunction, patients are at increased risk of¹⁰:

• tooth decay (dental caries) and erosion
• periodontal disease (e.g. gingivitis, periodontitis
• oral ulcerations/mucosal atrophy
• oral candidiasis
• difficulty with the retention of dentures
• sialadenitis (salivary gland inflammation, which may lead to infection).

Diagnosis

As a pharmacist, it is important to have open communication with patients to ascertain symptoms which may be associated with their complaint of dry mouth. The following questions will aid in determining whether symptoms are likely associated with salivary gland dysfunction^1,15:

1. Does the amount of saliva in your mouth seem too little or too much, or do you not notice it?
2. Do you need to sip fluids with food or prefer moist foods to aid in swallowing?
3. Does your mouth feel dry when eating a meal or even when talking?

Secondly, it is imperative to obtain a relevant medical and medicines history (current and past; e.g. Sjögren’s syndrome or a history of radiation therapy to the head and neck). Evaluate for potential polypharmacy and the presence of xerogenic medicines.¹⁶

Pharmacists are in a good position to appropriately refer a patient for further investigations while providing initial symptomatic management. Through referral, clinical factors can be evaluated by a dentist, which may include salivary quality and flow, presence of dental caries, oral cavity (mucosal) changes, or swelling in the salivary glands.¹⁷ Other potential oral conditions which may present with symptoms of dry mouth, such as burning mouth syndrome, nicotinic stomatitis, malignancy and oral lichen planus, can also be evaluated.

There are many conditions which may mimic the symptoms of dry mouth. Hence, an awareness of other potential differential diagnoses is necessary to ensure referrals to the dental practitioner (e.g. dentist or oral medicine specialist).

It is prudent for pharmacists to keep an eye out for possible red flags which may indicate similarly presenting but more serious conditions. Some examples include dysphagia and dysphonia (which may be symptoms of tonsillar or throat cancer), problems chewing or moving the tongue/ jaw, and swelling and/or redness in the mouth or throat. Mouth ulcers may often be seen in individuals affected by hyposalivation. However, in some cases, this ulceration may be malignant in nature.¹⁸ Please refer to the Australian Pharmaceutical Formulary (APF) non- prescription medicine guide: Mouth ulcers for further information on this symptom when presented in the pharmacy.

Management

The overall treatment goal is to minimise the symptoms of dry mouth, improve the patient’s quality of life and reduce complications associated with hyposalivation. Obtaining a provisional diagnosis based on questioning for an individual’s dry mouth symptoms is important for appropriate management. To manage symptoms of oral dryness, non-pharmacological and pharmacological therapies can be utilised.¹⁰

Non-pharmacological management

There are many systemic factors contributing to oral dryness, so holistic patient care is essential to eliminate or minimise the underlying cause.¹⁹ A patient should be screened by an appropriate medical practitioner for diabetes mellitus, thyroid disease, obstructive sleep apnoea, nutritional deficiencies and autoimmune inflammatory conditions, and managed appropriately should an abnormality be detected. The individual should also be reviewed by a dentist or an oral medicine specialist for the presence of oral mucosal disease.¹⁰

A review to detect xerogenic medicines should be undertaken, and potential deprescribing, dose modification or use of alternatives in consultation with the patient’s treating physician should be considered.¹⁰ Patients on oral inhalers should be instructed to rinse and gargle with water after using their inhalers as the beta₂ -agonists salbutamol and terbutaline can reduce saliva flow.²⁹

Some xerogenic medicines or lifestyle factors tend to cause dehydration. If the cause is easily identifiable as dehydration, drinking water can assist in reducing xerostomia.¹⁰ Additionally, adequate hydration can aid in washing away microorganisms in the mouth, reducing the risk of oral infections. Intake of coffee and/or tea should be limited due to their diuretic effect and risk of further dehydration.¹⁰ Salivary stimulants such as chewing gum may be used.¹⁰ Sugar-free products are advised (e.g. Extra Professional, Recaldent, 5 Gum). Note that for neonates, children, the elderly or special care populations, chewing sugar-free gum may not be favourable due to the potential aspiration risk.²⁰

Additionally, frequent use of chewing gum can contribute to temporomandibular symptoms. Additionally, electrostimulation may be utilised. For example, the use of a specialised intraoral handheld device which directly stimulates the neural pathways of the submandibular and sublingual salivary glands.³

Pharmacological management 

Salivary substitutes have been shown to improve patients’ symptoms.^21,22 These often must be used frequently during the day for notable benefit, and the benefit may vary between individuals. There are various products and methods of application such as oral gel, oral rinse or oral spray. Some common examples of artificial salivary products include Oral7 products, Oralube, Aquae products and Biotène products.²³ Sugarless lozenges may also aid in stimulating saliva.²³

Pharmacologically, pilocarpine is a cholinergic agonist which acts as a sialogogue (promotes salivation). It is commonly delivered through the ocular route to treat chronic open-angle glaucoma. However, it is sometimes prescribed off-label for xerostomia caused by certain conditions such as Sjögren’s syndrome or radiation for head and neck cancer. Some functioning salivary acini must be present for there to be some benefit.²⁴ Pilocarpine has several adverse effects and is generally contraindicated in individuals with significant cardiovascular and pulmonary disease.

Complementary medicine

Bicarbonate mouthwash (half a teaspoon of bicarbonate powder dissolved in a glass of warm water)¹⁰ can be used as an alternative lubricant, which can provide nourishment for the oral mucosa.

Prevention

Pharmacists can provide the following suggestions to help prevent or reduce severity of xerostomia or associated dental/oral consequences^10,25:

• Ensure hydration levels are adequate.
• Avoid alcohol-based products and smoking.
• Minimise consumption of acidic food and drinks (e.g. soft drinks, juice, sports drinks) to reduce mucosal irritation and dental decay risk.
• Ensure regular dental examinations at least every 6 months.
• Maintain good oral hygiene and use of fluoride-containing toothpaste.
• Limit consumption of caffeine (milk may be added to tea/coffee to lessen drying effect on the mouth).
• Chew food well to stimulate flow of saliva.
• Reduce sugar intake and limit snacks high in sugar.

If there is inadequate saliva production, the remineralising effects of calcium and phosphate are deficient. This can lead to dental decay (i.e. dental caries). Therefore, a dental practitioner may recommend products containing either fluoride (e.g. high concentration sodium fluoride; Neutrafluor 5000, Duraphat varnish) or calcium phosphate derivative (e.g. casein phosphopeptide-amorphous calcium phosphate-nanocomplexes; Tooth Mousse) to confer a protective effect to the teeth.²⁶ It is important to reiterate to the patient not to rinse after use but only spit to allow supersaturation effects of the remineralising agent.²⁷

Follow-up

The follow-up required can vary among the individuals involved. If the dry mouth symptoms were diagnosed to have been induced by a medicine, the symptoms will often resolve once the medicine has been ceased or the dose changed. However, for dehydration-related issues, adequate hydration can resolve symptoms but improvement time may vary depending on the severity of the dehydration or management of the cause of dehydration, such as in systemic disease-causing water loss (i.e. uncontrolled diabetes, diarrhoea).²⁸ It is advisable to encourage patients to adhere to suggested treatments and attend follow-up visits with their dentist to help build rapport and improve adherence.

Knowledge to practice

Pharmacists can aid in the management of dry mouth by providing patients with knowledge of the types of oral salivary substitutes/stimulants available and the method of use.

Most dry mouth symptoms can be managed through use of saliva substitutes and stimulants.

Pharmacists can also talk with patients who are taking xerogenic medicines about the potential adverse effects of dry mouth and dental implications, suggest preventive strategies and liaise with dental and medical practitioners for any further investigation.

Pharmacists should be aware of the potential red flags which may mimic dry mouth symptoms, and ensure timely referral and follow-up with dental or medical practitioners.

The promotion of inter-professional practice will not only improve holistic patient care, but it will also promote collaboration of all health professionals within the healthcare sector.

Conclusion

Dry mouth can be debilitating for patients, but pharmacists are in a perfect position to improve a patient’s quality of life. However, it is important to not just focus on presenting symptomatology, but to look at the bigger picture and ensure that the actual cause of the symptoms is also being managed.

Key points

• Dry mouth can have many causes. However, it is mostly caused by medicines.
• Pharmacists can be at the forefront of assisting patients with dry mouth, identifying potential causes and advising on preventive strategies and good oral hygiene.
• Most of the salivary substitutes will only treat the symptoms, not the disease.
• Referral and consultation with a dental and/or medical practitioner can ensure any potential causes or differential diagnosis of similarly presenting conditions are ruled out and managed appropriately.

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Our authors

Dr Janina Christoforou (she/her) BDSc(Hons), DClinDent(Oral Med/Oral Path) WAus, FRACDS(GDP), MRACDS(Oral Med), FOMAA, FPFA has completed her specialisation in oral medicine and oral pathology from the University of Western Australia. An oral medicine specialist in private practice, she holds consultant public hospital positions and is an Adjunct Senior Lecturer at UWA.

Dr Alex Park (he/him) BPharm, PGDipHighE Otago, ProfHonsClinPharm Tas, DMD WAust, MPS, MSHP is a Senior Lecturer in general dental practice and pharmacology at the UWA Dental School. He is a registered pharmacist and a dentist with a broad research and teaching profile.

Our reiewer

Morna Falkland (she/her) BPharm

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