Most of us take it for granted that our mouths are moist and that we will be able to spit when we want to (a function that has become even more important now that saliva-based genetic testing has become popular). But like every other bodily function, things can go wrong because of changes in salivary gland functioning due to aging, or diseases, or as a side effect of medications that we take.
It has been estimated that dry mouth, known in the medical world as xerostomia, affects 30% of adults over 65 and 40% over 80. People with dry mouth complain that their mouth is not just dry, but also sticky. They may say their saliva feels thick and ropy. Dry mouth may interfere with chewing, swallowing, tasting, and even speaking. And it can cause an alteration in taste for spicy, salty, or sour foods.
Dry mouth is annoying, but it is also associated with medical consequences, such as an increase in dental caries (cavities), periodontal disease, halitosis (bad breath), mouth sores, oral candidiasis (a fungal infection), trouble chewing and swallowing that can lead to unwanted weight loss, and salivary calculi (stones).
Causes of dry mouth
The underlying cause of dry mouth is hypofunction of the salivary glands. This can be due to medical conditions (such as Sjogren’s syndrome, rheumatoid arthritis, lupus, other autoimmune disorders, mumps, cystic fibrosis, lymphoma) and a number of other conditions. Hormonal changes, such as those that occur during pregnancy or menopause, have also been listed as causes.
Dry mouth can also be a side effect of some medical treatments, such as radiation to the head and neck or chemotherapy treatments for cancer that damage the salivary glands. In addition, dry mouth can be caused by medications. In fact, dry mouth is one of the most common adverse effects related to medication use in older adults.
According to the Surgeon General’s Report on Oral Health in America, more than 400 over-the-counter and prescription medications can contribute to oral dryness including,
- antihistamines (for allergy or asthma)
- antihypertensive medications
- pain medications
- muscle relaxants
The most common types of drugs causing dry mouth have anticholinergic effects. They block the neurotransmitter acetylcholine. Dry mouth is only one of a myriad of anticholinergic side effects of these types of drugs. There is also evidence older people taking four or more medications may be more likely to develop dry mouth.
In order to learn more about drug-induced dry mouth in seniors, a team of researchers led by Edwin Tan, Ph.D at the Karolinkska Institutet in Stockholm, Sweden performed a systemic review and meta-analysis of the scientific literature on the topic. They published their results on October 26, 2017, in a paper titled, “Medications That Cause Dry Mouth As an Adverse Effect in Older People” in the Journal of the American Geriatric Society.
What did the study find?
Overall, they found that medication use, the number of medications, and using a wide range of medication classes were significantly associated with salivary gland hypofunction, low salivary flow rate, and dry mouth. In studies that had a control group, more people on drug treatment reported dry mouth than those on placebo.
They also found that specific drugs, such as those from therapeutic classes used for urinary incontinence, antidepressants, and psycholeptics, were significantly associated with xerostomia.
- Drugs for urinary incontinence, for example, were almost 6 times as likely to cause xerostomia than a placebo. Tolterodine and oxybutynin, drugs for the treatment of overactive bladder, were cited in 4 and 3 studies, respectively. These drugs work through a non-selective antimuscarinic mechanism, inhibiting the activity of the neurotransmitter, acetylcholine. This leads to smooth muscle relaxation (thus relieving symptoms of overactive bladder), but they also decrease secretion of saliva, sweat, and digestive juice and dilate the pupil of the eye. Newer drugs, such as darifenacin and solifenacin are M3 selective receptor antagonists and may be more bladder-specific and have fewer side effects such as dry mouth. Mirabegron, a beta-3 adrenergic receptor agonist, another alternative to nonselective antimuscarinic drugs, appears to be less likely to cause dry mouth.
- Antidepressant drugs are another class of drugs found to be a frequent cause of dry mouth in older people. The authors of the study point out that duloxetine, a selective serotonin and noradrenaline reuptake inhibitor (SSNRI), was cited as a cause of dry mouth in 4 of the studies that the researchers reviewed. Other drugs mentioned were escitalopram, a selective serotonin-reuptake inhibitor (SSRI) and doxepin, a tricyclic antidepressant (TCA).
- Psycholeptic medications including antipsychotics, anxiolytics, and hypnotics can also cause dry mouth.
Is there any treatment for dry mouth?
There are three main goals in the treatment of dry mouth:
- Preventing or reversing the dryness, if possible
- Relief of symptoms
- Maintenance of oral health with particular attention to dental caries
- If dry mouth is caused by prescription medications and if those medications can be stopped or switched to another effective drug that doesn’t cause the symptom, that should be done. If there is no substitute for a medication that causes dry mouth, symptoms may be reduced by taking the drug in the daytime rather than at night or taking it in divided doses instead of one large dose. These types of changes should be discussed with the prescriber to be sure that these changes don’t impact the desired therapeutic effect.
- If the culprit is an over-the-counter diphenhydramine sleep aid (such as Benedryl), try non-medication alternatives to help you sleep better. Cold medications often contain diphenhydramine and other substances, such as phenylephrine, that cause dry mouth. In order to avoid dry mouth-associated oral health issues, do not take them over a prolonged period of time
- Caffeine and alcohol can cause dryness and irritation and should also be avoided, including mouthwash that contains alcohol.
- Tobacco products can dry and irritate your mouth. Do not use them in any of their forms (cigarettes, cigars, chewing tobacco).
Relief of symptoms:
There are many different over-the-counter products—including mouth rinses, oral sprays and gels, and lozenges—that are marketed for relief of dry mouth. Although a 2011 Cochrane Review failed to find strong evidence that any of them actually worked, subjective relief is highly individual, so it is worth trying different products to see what works best for you. It is worth noting that mouthwashes designed for dry mouth that contain xylitol can also offer some protection against tooth decay.
Artificial saliva products are available both with and without a prescription. They usually contain carboxymethylcellulose and glycerin to increase viscosity and buffering and flavoring agents, such as xylitol or sorbitol. Unlike natural saliva, however, they do not have digestive and antibacterial enzymes.
If you have severe dry mouth, your doctor or dentist may prescribe pilocarpine (Salagen, Eisai, and generics) or cevimeline hydrochloride (Evoxac capsules, Daiichi-Sankyo, and generics) to stimulate saliva production
In addition to the advice from your doctor, these home remedies may help relieve dry mouth symptoms:
- Sipping water or sucking on ice chips throughout the day can provide symptomatic relief. If drinking water in the evening leads to nighttime awakening to urinate, water can be swished and spit out instead. Drinking water during meals may help with chewing and swallowing.
- Chew sugar-free gum or suck on sugar-free hard candies to stimulate salivary flow and provide temporary relief. Be sure that the candies and gum are labeled as sugar-free so they don’t worsen the tendency to dental caries that occurs as a result of dry mouth. Read the label to be sure they have not substituted another sugar, such as fructose, that can cause caries and check out the calories per piece so that you don’t inadvertently pile on the pounds while trying to treat your dry mouth. Products that contain xylitol may be a good choice since it is a natural sweetener, has 40% of the calories of sugar, and may prevent dental caries. Beware, however, as xylitol can cause gas or diarrhea in some people if consumed in large amounts.
- Over-the-counter saliva substitutes that contain xylitol or that contain carboxymethylcellulose or hydroxyethyl cellulose can also provide symptomatic relief.
- If possible, breathe through your nose, not your mouth. You may need to talk to your doctor about treatment for snoring, congestion, or allergies.
- A room humidifier adds moisture to the air at night which may reduce symptoms, particularly when used in the bedroom at night
Maintain your oral health:
Saliva is important to maintain the health of your teeth and mouth. Taking these steps to protect your teeth may also help your dry mouth condition:
- Brush with a fluoride toothpaste at least twice a day and floss your teeth or use interdental brushes. Ask your dentist if you might benefit from prescription fluoride toothpaste, toothpaste containing betaine, or a tooth gel to neutralize bacteria acids.
- Use a fluoride rinse or brush-on fluoride gel before bedtime. In some cases, your dentist might want to apply a fluoride varnish or fit you for fluoride trays, which you fill with fluoride and wear over your teeth at night.
- Your dentist may also recommend the weekly use of a chlorhexidine rinse to control cavities.
- Avoid sugary or acidic foods and candies because they increase the risk of tooth decay.
- See your dentist at least twice yearly to have your teeth examined and plaque removed to help prevent tooth decay.