Dry Mouth: Its Etiology, Symptoms, and Strategies for Management

Précis

Pharmacists with a deeper knowledge of xerostomia are ideally positioned to help educate patients with dry mouth on making informed self-care decisions for effective symptom management and improved quality of life.

Abstract

Dry mouth, or xerostomia, is a frequently occurring affliction that can negatively influence oral functioning and an individual’s quality of life. It is a subjective sense of mouth dryness associated with numerous etiologies that can impair salivary gland functioning. Due to xerostomia’s subjective nature, there is no single, universally effective treatment regimen, which makes finding the best approach for each patient a challenge for health care professionals (HCPs). Oral hygiene maintenance, lifestyle modifications, and use of salivary substitutes and stimulants play an important role in appropriate management of dry mouth symptoms. This article provides an overview of dry mouth and its etiology and symptoms as well as insights on management strategies that can help pharmacy professionals and other HCPs better understand the condition to inform their decision-making and the educational support they provide on symptom management.

Introduction

Dry mouth, or xerostomia, is a subjective sensation of mouth dryness that is characterized by reduced salivary flow (ie, hyposalivation; saliva production < 0.1 mL/min at rest or < 0.7 mL/min under stimulation) or an altered rheology of saliva.¹ Investigators in a 2018 meta-analysis reported that 27.1% of the US population has been diagnosed with dry mouth, which is more than in Europe (20.4%) and Australasia (18.6%), and suggested an increase in prevalence with age.² Based on our literature search, most studies on dry mouth have focused on older individuals, with none involving children or adolescents. Additionally, few studies have reported the occurrence of hyposalivation in children.^3,4

Saliva, primarily composed of 99% water and 1% organic and inorganic substances (Figure 1^1,5), serves essential functions such as providing lubrication, antimicrobial action, and pH buffering as well as facilitating speech, swallowing, food digestion, and flavor diffusion.¹ Clinically, the effects of dry mouth can range from mild discomfort to impeded oral functioning, an increased risk of developing dental caries and oral infections, and a worsened quality of life (Figure 2).^6-8 Because no cure is available for dry mouth, palliative care—including lifestyle modifications, oral hygiene maintenance, and pharmacotherapies such as salivary substitutes and stimulants—remains crucial for managing the condition.

Recent data highlight that pharmacists frequently encounter patients with oral health issues, including dry mouth.⁹ However, a significant barrier identified by pharmacists is a lack of knowledge in oral health care.¹⁰ This article aims to provide an overview of dry mouth, emphasizing its etiology, symptoms, and management strategies. By understanding these aspects, pharmacists can empower individuals with dry mouth to make informed self-care decisions and ensure effective symptom management.

Pathophysiology and Other Factors Associated With Dry Mouth

Xerostomia is not a separate clinical entity, but rather, a sign of several etiologies that can impair the functioning of the salivary glands (Table 1).^6,7,11 Risk factors commonly associated with dry mouth include certain systemic diseases, xerogenic medications, head-and-neck radiation, developmental issues, older age, menopause, various psychological conditions, and lifestyle choices.

Systemic Diseases

Sjögren syndrome is the most recognized autoimmune disease associated with dry mouth and is characterized by the atrophy of the salivary glands followed by hyposalivation.¹¹ Rheumatoid arthritis, chronic juvenile arthritis, sarcoidosis, and systemic sclerosis correlate significantly with dry mouth.⁷ Other systemic diseases leading to dry mouth include diabetes, renal disease, bacterial and viral infections (eg, hepatitis C virus infection), liver disease, amyloidosis, and thyroid disease.⁷

Medication-Induced or Head-and-Neck Radiation–Induced AEs

Dry mouth is frequently observed as an adverse effect (AE) of prescription and OTC medications that are known xerogenic agents. Most cases are attributed to the anticholinergic effects, followed by sympathomimetic effects, vasoconstriction in salivary glands, dehydration, topical effects of inhaled medications, alterations in electrolyte and fluid balance, and changes in saliva composition. Patients who receive head-and-neck radiation therapy also commonly experience dry mouth due to radiation-induced damage to salivary glands.¹²

Developmental Issues

Rare developmental failure in salivary glands (partial or total) causes childhood xerostomia, occurring in 1 of 5000 births. Pathogenesis is unclear but linked to fetal development defects and sympathetic denervation, causing atrophy or hypertrophy in glands—and parasympathetic denervation results in glandular weight loss.¹³

Age

Age is a significant predictor of perceived mouth dryness.¹⁴ Aging induces multiple structural, functional, and metabolic alterations in salivary glands,¹⁵ and the high incidence of comorbidities and polypharmacy increases the risk of dry mouth symptoms in older adults.

Menopause

A significantly higher number of postmenopausal women experience reduced salivary flow rate and lower pH levels compared with menstruating women.¹⁶ Dry mouth can become more common in women after menopause because estrogen levels are permanently low.¹⁷

Psychological Conditions

Psychological conditions such as anxiety and depression show a statistically significant relationship with the rate of unstimulated salivary flow and dry mouth. Anxiety suppresses the impulses from the salivary nuclei to salivary glands, resulting in hyposalivation and dry mouth. Depression stimulates anticholinergic pathways, causing reduced salivary flow.18

Lifestyle Choices

Smoking, consuming alcohol, and drinking caffeinated beverages can alter salivary flow rate and increase the risk of dry mouth or aggravate the condition.^19-21

Self Care Management Options for Dry Mouth Symptoms

In the absence of a cure for dry mouth, management strategies such as lifestyle modifications, salivary stimulants, and salivary substitutes are crucial for alleviating symptoms.

Lifestyle Modifications

Good oral hygiene and adequate hydration are important for individuals with dry mouth.²² Maintaining proper oral health hygiene, including using fluoride toothpaste, flossing daily, and visiting the dentist at least twice a year, is crucial for preventing dry mouth–associated dental complications such as dental erosion, demineralization, and caries.^23,24 Additional lifestyle modifications include using bedside humidifiers; finding ways to reduce stress; and avoiding spicy and dry food, caffeinated or carbonated drinks, alcohol, smoking, and mouthwashes containing alcohol.²²

Salivary Stimulants

Salivary stimulants, also known as sialogogues, increase salivary secretion. The salivary glands can be stimulated via pharmaceutically driven (pilocarpine or cevimeline [Evoxac; Daiichi Sankyo, Inc]), acid-driven (1% malic acid spray or 3% citric acid spray), or mechanically driven (chewing gum) approaches. Pilocarpine is typically prescribed at a dose of 5 mg 3 times a day for at least 3 months, and cevimeline is prescribed at a dose of 30 mg 3 times a day for at least 3 months.²³ Both agents are cholinergic, parasympathetic agonists, and their AEs include sweating, cutaneous vasodilation, nausea and vomiting, diarrhea, hiccups, hypotension, bradycardia, increased urinary frequency, bronchoconstriction, and vision problems.²³ If there is extensive damage to the salivary glands, individuals may not have a good response to these medications; therefore, these agents should only be considered in patients with residual salivary gland function.²³ Use is contraindicated in individuals with hypersensitivity, narrow-angle glaucoma, and uncontrolled asthma.²³ These products are only available with a prescription.

OTC sugar-free chewing gum and lozenges also are available. Sugar-free chewing gum or a lozenge can increase saliva secretion through mechanical stimulation of the major salivary glands.²⁵ A Cochrane Collaboration review reported that chewing gum increased saliva production only in individuals with residual secretory capacity.²⁵ Moreover, saliva stimulated by mechanical sucking or chewing alone has different rheological properties and does not generate the same mucoadhesive film as unstimulated saliva.²⁶

Saliva Substitutes

Saliva substitutes provide moisture, lubrication, and oral comfort by replicating some properties of natural saliva and do not alter the salivary flow in patients with dry mouth.²⁷ They come in various forms, including a mouthwash/oral rinse, a moisturizing spray, and an oral-balance moisturizing gel. Some are available over the counter, and others require a prescription (Table 2^28-36). Alcohol-and sodium lauryl sulfate–free products are gentle on the oral mucosa and promote enhanced patient adherence.

Clinical study data show that saliva substitutes effectively relieve dry mouth symptoms such as impaired swallowing, hoarseness, speech problems, oral pain, halitosis, and loss of taste.^37-42 Most patients with dry mouth and mild symptoms can sip water to achieve good short-term symptom relief; however, water is less effective in patients with moderate to severe symptoms of dry mouth because it is short acting.²⁷ Saliva substitutes provide better symptom-relieving effects on dry mouth, adhesion to oral mucosa, and persistence of taste compared with water.^14,38-40 The duration of saliva substitutes ranges from 1.5 to 4 hours.^{37,38,41,43,44}

Considerations for Pharmacists

Pharmacists play a vital role in assisting patients with choosing self-care approaches and optimal OTC medicines. Although no specific guidelines are available for managing dry mouth, pharmacists should consider the following when counseling patients with the condition:

• Medical history: Dry mouth is often associated with underlying health conditions or medication use. Consider asking patients on multiple medications that can cause dry mouth whether they are experiencing symptoms of dry mouth after picking up their latest refill medications or starting a new medication that can cause dry mouth. During counseling, assess whether patients have any medical conditions associated with dry mouth and evaluate dry mouth symptoms by prompting patients about specific symptoms such as oral dryness. Management of dry mouth starts with a thorough evaluation, focusing on the illness and ongoing medicines. Although some medical conditions such as autoimmune or neurologic dysfunctions are not completely curable and will require ongoing palliative treatment for dry mouth, others such as nutritional imbalances or infectious conditions can be treated with a resolution that eventually relieves dry mouth. Some medications (eg, analgesics) may also be modified or replaced to address the presence of dry mouth, whereas others cannot and will require the patient to choose self-care approaches for managing dry mouth. Use of medications that cause sialorrhea, or hypersalivation, could potentially help counteract the effect of dry mouth. However, be sure to advise patients on xerogenic medications who are experiencing dry mouth to consult with their health care provider (HCP) before making any medication changes.
• Patient education: Improving patients’ awareness through counseling and education about lifestyle modifications and proper oral hygiene is essential. Educational resources that pharmacists can use to support these activities are available from the American Dental Association and Health Resources and Services Administration and can be found on their websites.
• Pharmacotherapies: Salivary stimulants and substitutes offer immediate relief for dry mouth discomfort, enhancing quality of life. Sugar-free gum may help only patients with residual salivary gland function, whereas saliva substitutes can be used as needed by all patients with dry mouth for symptomatic relief.²⁵ An ideal substitute should mimic human saliva properties, taste pleasant, and offer convenient self-administration to promote patient adherence. Understanding patient preference is essential while also considering potential AEs. A sampling of the commercially available salivary substitutes is shown in Table 2. In patients with radiation-induced xerostomia or Sjögren syndrome, consider the gel-based salivary substitutes, which are placed directly on the tongue and spread thoroughly inside the mouth for a long-lasting effect; their use is especially advisable before eating. Artificial saliva with oxidized glycerol triesters can be used in patients with chronic and temporary mouth dryness due to any systemic disease, stress, or aging.²⁵ Denture wearers with dry mouth can consider using a salivary substitute gel under dentures to improve comfort. In dentulous patients (ie, those with natural teeth), pH-neutral salivary substitutes containing fluorides and xylitol must be used to prevent tooth decay. Moreover, use of saliva substitutes in the form of mouth rinses containing zinc ions can help eliminate halitosis while comforting dry mouth. Calcium phosphate–containing salivary substitutes are indicated for patients with xerostomia due to radiation therapy or medicines such as atropine, antihistamines, or anticholinergic agents. Patients who are restricted to a low-sodium diet must be advised to consult their HCP before using sodium-containing products.

Conclusion

Dry mouth, although often overlooked,² is a common condition. Because there is no cure for dry mouth and because of its multifaceted causes, managing it presents challenges for HCPs. Pharmacists can identify patients at risk for dry mouth during patient encounters, educate patients on the condition, raise awareness by prompting patients to assess for dry mouth symptoms, and inform them of the existence of treatment options. The recommendations outlined, such as hydration strategies, healthy oral hygiene practices (eg, gentle toothbrushing at least twice daily with a fluoride toothpaste), and OTC solutions such as sugar-free chewing gums and saliva substitutes, can help relieve dry mouth symptoms. The practicality of providing this type of educational support in a pharmacy underscores pharmacists’ pivotal role in palliative care of xerostomia as well as their accessibility to patients. Continued collaboration between patients, pharmacists, and other HCPs promotes a holistic approach to managing this common but underrecognized condition.

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Conflicts of interest: Authors Ellen Guritzky and Carmen Cheung are employees of Haleon.

Funding: This article received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Acknowledgement: Medical writing support was provided by Swati Gupta, Syed Obaidur Rahman, and Nitu Bansal from Knowledge Centre, WNS Global Services.