Dealing With Dry Mouth in Lambert-Eaton Myasthenic Syndrome (LEMS)

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune condition that disrupts communication between nerves and muscles, leading to weakness that often starts in the hips and legs.

“People with LEMS can experience a group of symptoms we call dysautonomia, which can include dry mouth, dry eyes, constipation, erectile dysfunction in men, or lightheadedness,” says Syed Ahmed, DO, an assistant professor of neurology at UT Southwestern Medical Center in Dallas.

One example is oral thrush, a fungal infection that can cause creamy white patches on the tongue or inner cheeks, along with soreness or a burning sensation.

Because dry mouth in LEMS is tied to both nerve signaling and gland function, treatment often involves more than one approach.

Doctors typically start by treating LEMS itself: "By improving the overall autoimmune process, it also provides some benefit for autonomic symptoms like dry mouth,” says Dr. Ahmed.

Treatments for LEMS include:

• Immune-modulating therapies such as corticosteroids and intravenous immunoglobulin (IVIG)
• Amifampridine (Firdapse) and guanidine, which increase the release of acetylcholine to improve nerve-to-muscle signaling
• Pyridostigmine (Mestinon), which slows the breakdown of acetylcholine and may be used alongside amifampridine to support both muscle strength and symptoms like dry mouth, dry eyes, and constipation (this use is off-label)

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Even when LEMS is well managed, dry mouth may not fully resolve. “We often still have to treat dry mouth directly,” says Ahmed.

Treatments that target dry mouth include:

• Saliva-stimulating medications, including cholinergic agonists such as pilocarpine (Salagen) and cevimeline (Evoxac), may be prescribed to directly stimulate salivary glands
• Prescription-strength dry mouth lozenges, such as sorbitol (Numoisyn), help keep the mouth moist

Over-the-counter (OTC) products can help take the edge off dry mouth symptoms. OTC products are broadly divided into saliva substitutes and saliva stimulants, which increase saliva production.

Saliva substitutes, made of a mix of ingredients such as carboxymethylcellulose, polyethylene glycol, sorbitol, glycerine, and electrolytes, are available as gels, sprays, and rinses. These are designed to mimic natural saliva and keep the mouth moist, making it easier to speak, eat, and sleep comfortably.

These types of supportive tools can be useful alongside medical treatment, particularly for managing symptoms throughout the day, says Ahmed.

Daily habits can make a noticeable difference in managing dry mouth.

Miriam Freimer, MD, a neurologist at the Ohio State University Wexner Medical Center in Columbus, suggests starting with the basics.

“The best thing to do is to always have something to drink handy, preferably water. Also, sucking on sugar-free hard candies may be helpful as well,” Dr. Freimer says.

Other coping strategies for managing dry mouth include:

• Sucking on ice chips or sugar-free lemon drops
• Chewing sugar-free gum
• Using lip moisturizers regularly (every few hours)
• Drinking fluids while eating to make food easier to chew and swallow
• Using a humidifier at night to reduce dryness

It can also help to avoid things that make dryness worse, such as:

• Alcohol, tobacco, and caffeine
• Alcohol-containing mouthwashes
• Salty, spicy, or dry, hard-to-chew foods
• Sticky or sugary foods

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If dry mouth is persistent or starts to interfere with eating, speaking, or oral health, it is important to bring it up with your healthcare provider.

Warning signs include mouth sores, white patches, difficulty swallowing, or dryness that does not improve with the strategies outlined above.

Managing LEMS-related dry mouth often requires coordination between specialists.

“As in many areas of medicine, a multidisciplinary approach is best; to really optimize care, patients often also need support from other specialists, including dentists,” says Ahmed.

This matters, because dental complications from dry mouth — such as cavities or gum disease — can develop gradually and may not be obvious until they are more advanced.

Between visits to the dentist, practice good oral hygiene, including:

• Brush gently at least twice a day with fluoride toothpaste.
• Floss daily.
• If you use mouthwash, choose alcohol-free formulations. Alcohol can further dry and irritate oral tissues.

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• Dry mouth is common in LEMS because the condition disrupts autonomic nerve signaling that controls saliva production.
• Over time, low saliva can increase the risk of cavities and gum disease and cause difficulty eating or speaking.
• Managing dry mouth may involve optimizing LEMS treatment, using medications that stimulate saliva, and reviewing other drugs that can worsen dryness.
• Daily habits like sipping water, sucking on lozenges or sugar-free candy, and maintaining good oral hygiene can help ease symptoms and protect oral health.