Burning Mouth Syndrome: A Strange Condition Affecting Millions

Have you ever felt your mouth was on fire? Have you ever felt as if placing your tongue in the freezer would be the only way to find relief? Have you ever had a prolonged metallic or bitter taste in your mouth? If you have—you may have experienced what is known as burning mouth syndrome (BMS).

This condition is difficult to diagnose, difficult to treat, and there is not a lot of agreement in the research as to the specific nature of BMS. For those having experienced this condition, a common experience is of visiting an ENT or dentist and being told all tests are normal. Still—the symptoms persist and there is clearly something wrong. Let’s try and get a better idea of what that may be.

Highlights

• Burning Mouth Syndrome (BMS) is a globally recognized medical condition
• It has a large list of associated symptoms that varying greatly
• Has several sub-types that have commonly associated medical conditions
• Characterized by a burning sensation is located primarily in the mouth, tongue, gums, and palate
• There is no known cause of this condition, though research is proving insightful

Introduction

The National Institute of Dental and Craniofacial Research (NIDC) defines burning mouth syndrome as “a painful, complex condition often described as a burning, scalding, or tingling feeling in the mouth that may occur every day for months or longer. Dry mouth or an altered taste in the mouth may accompany the pain.”

As someone who experiences this condition regularly, I can attest to the accuracy of this definition. In their official BMS resource page, the NIDC quickly notes that doctors and dentists do not have BMS-specific testing protocols.

Prevalence

Burning Mouth Syndrome is estimated to affect roughly .1% of the general population with women being more affected than men (7). After the age of fifty, these rates increase significantly to rates as high as .5% in ages 70-79 (8). The ratio of women suffering from BMS to men is, roughly, seven-to-one.

Initial reports of BMS, when characterized solely by “a prolonged burning of the mouth” were observed to be as high as nearly 15%. As more rigid diagnostic criteria evolved, however, the incidence rates of BMS fell to as low as .7%. Researchers in the field note this rate is likely to be under-representative of global BMS rates (9).

Very few population-based studies have been done to assess the prevalence of BMS. Of those I have seen, rates of BMS are noted as being relatively low among the general populations—but still readily reported and observed. These reports range in location from around the world indicating that BMS is of global concern.

Anxiety & Stress Connection

In a study of fifty-six women with BMS, researchers noted that many participants noted adverse and stressful life events leading up to their BMS (2). Researchers used formalized questionnaires to assess both personality traits and perceived stress as well as a general questionnaire to assess lifestyle and health practices.

Compared to controls, researchers found those suffering from BMS reported higher levels of perceived stress and lower levels of weekly physical activity. Researchers conclude that BMS therapies focused on reducing stress and increasing physical activity may be beneficial.

Hormonal Connection

Burning mouth syndrome has been linked to several variations of hormonal imbalance. One study found that women suffering from burning mouth syndrome were had significantly (p = .003) levels of morning salivary DHEA (13). Another study found that BMS patients were significantly more likely to be suffering from hypothyroidism. Treatment with thyroxine and lipoic acid demonstrated positive results in many patients (14).

Gaining Attention

The COVID-19 pandemic has brought with it a global focus on medical-centered research like no other in modern history. With respect to BMS, the symptomology of COVID-19 has been noted to include (among many other oddities) BMS (10).

One study that sought to catalog the spectrum of COVID-19 symptoms noted that a significant number of both men and women reported BMS as a result of COVID-19 infection (11). Oddly enough, these reports had no statistical correlation with those reporting rhinorrhea (runny nose) or nasal congestion.

Symptoms

The symptoms of Burning Mouth Syndrome are easily inferred by the condition’s name, for the most part. Through efforts to better characterize and catalog the condition, researchers have posed the following descriptions of generalized BMS symptoms (9):

• variety of chronic oral symptoms that often increase in intensity at the end of each day, and that seldom interfere with sleep;
• a “symptomatic triad”, which includes unremitting oral mucosal pain, dysgeusia, and xerostomia; and  “no signs” of lesion(s) or other detectable change(s) in the oral mucosa, even in the painful area(s);
• altered perception of sensory/chemosensory functions as well
  as to the changes in the psychological profile;
• a prolonged “burning” sensation of the oral mucosa, similar in intensity to, but different in quality from, that associated with toothache. However, scalding, tingling, or numb feelings of the oral mucosa have also been reported;

In an exhaustive summary of BMS-related case reports, researchers condense the description of BMS thusly (9):

… pain episodes [that] must occur continuously for at least 4-6 months. They may last for 12 years or more, with an average duration of 3.4 years. Pain levels may vary from mild to severe, but moderate pain is the most frequent presentation. The mean severity of BMS pain has been assessed at about 5-8 out of 10 using a Visual Analogue Scale (VAS) where 0 is no pain and 10 is the worst.

A more concise description of the physical symptoms of BMS, distilled from a survey of many different reports, is as follows:

1. Burning pain
2. Altered taste perception (dysgeusia)
3. Dry Mouth (xerostomia)
4. Altered pain tolerance
5. Altered perception of temperature

Common behavioral symptoms may include the following:

1. Cheek biting
2. Tooth grinding
3. Jaw clenching
4. Tongue thrusting

BMS researchers have also noted a common set of psychological symptoms associated with many patients. While the nature of these related symptoms is still unclear, the following are often related:

1. Unfavorable experiences with pain
2. Difficult early childhood experiences
3. Poor adaptation to school or work
4. Poor family life or marriage
5. Financial problems

Regarding these psychological symptoms, researchers note common complaints of associated conditions such as facial pain, TMJ disorders, anxiety, depression, decreased socialization, dizziness, mood changes, and several more.

The list of burning mouth symptoms certainly doesn’t look like most lists one finds when Googling. It’s long, diverse, and spans a myriad of physical, mental, and emotional presentations. One convenient aspect of BMS is that most physical symptoms are located in common areas of the mouth.

Where Does it Burn

Researchers note that burning mouth syndrome is characterized by unpleasant sensations in multiple locations in the mouth and sometimes sinus regions. BMS suffers often report unpleasant burning sensations in the following areas:

1. Tongue
2. Lower Lip
3. Hard Pallete (front portion of the mouth roof)
4. Upper Lip
5. Gumlines

Researchers also note that burning on the inner part of the cheeks and floor of the mouth is much less common and rarely reported among BMS sufferers. Associated pain may also be reported in the neck, jaw joints, shoulders, and muscles just under the lower jaw (suprahyoid) (9).

BMS Subtypes

Research has suggested that BMS presentation may be functionally divided into 3 primary subtypes:

Type 1:

Pain-free upon waking, worsening throughout the day, and peaking in the evening. This sub-type is commonly associated with issues such as nutritional deficiencies, diabetes, or underlying infection. This subtype does not commonly affect sleep quality in most cases.

Type 2:

This subtype consists of constant pain throughout the day that can make falling asleep at night difficult. Common to this form of BMS are mood changes, changes in appetite, and decreased lack of interest in socializing. Suffers of this form of BMJ is often noted as having dysfunction of the salivary glands associated with the use of antidepressants.

Type 3:

This subtype of BMS presents with intermittent symptoms often accompanied by pain-free periods. These cases generally report anxiety and allergic reactions to compounds such as food additives. This subtype is considered less attractive of clinical study but still likely useful in better understanding the localized factors that lead to BMS development.

Diagnosis

Diagnosing BMS is pretty straightforward. Your doctor or dentist will ask you something like “does your mouth burn? do you have a metallic or bitter taste that won’t go away?” If you answer “yes,” you are likely to be told that you have BMS. The NIDC diagnoses burning mouth syndrome as either a primary diagnosis or secondary.

Primary BMS

A diagnosis of primary burning mouth syndrome describes cases where there is no evidence of other contributing medical conditions. In such cases, doctors may run further tests to assess damage to nerves that control pain or taste (Trigeminal Nerve) (2).

Secondary BMS

A diagnosis of secondary burning mouth syndrome describes cases where underlying conditions such as hormonal imbalances, fungal infections (oral candida), autoimmune conditions (Sjögren’s), vitamin deficiencies (B12), or a whole slew of others.

Treatment Options

The NIDC, as well as others such as the Mayo Clinic, have a few suggestions of how to treat BMS. In my experience, few offer long-term relief but several can be helpful.

• Avoid spicy and acidic foods
• Avoid stress
• Avoid tobacco
• Avoid mouthwashes that contain alcohol
• Chew on ice chips
• Sip a cold beverage

I read these suggestions and have a hard time not laughing (crying) because they seem reflective of an overall lack of insight. In other words, there is no official treatment for BMS because there is no official consensus as to the true nature of BMS. In my own research, I have found some curious connections between BMS and commonly-reported/noted characteristics of patients.

Note: I reached out to the Mayo Clinic to determine their acceptance of patients suffering from Burning Mouth Syndrome. I was informed they don’t accept patients whose symptomology includes burning mouth syndrome.

Alternative Treatment Options

BMS is a condition with a broad set of symptoms. As one might imagine, this results in a broad landscape of possible pathologies, root causes, and potential therapies. In some cases, BMS may be a primary condition while in others it may reflect some deeper issue. As such, a medical consensus is lacking with respect to approved treatment protocols. That’s the bad news.

The Good News is that researchers around the globe are diligently trying different therapies for BMS. These treatments range from topical benzodiazepine rinses to frequency-specific modulation therapies. Below is a listing of clinically studied treatments for BMS that have shown some marked degree of success

Disclaimer: These are not approved therapies for BMS and you should have a discussion with your primary doctor before considering any of the information presented here.

Antidepressants

One study found that long-term treatment with antidepressants (venlafaxine and clonazepam) significantly reduced BMS symptoms (1). In this study, I found several notations by the authors that were particularly interesting:

1. Chronic exposure to stress or pain can cause mal-adapted hormonal and neurotransmitter mediated responses;
2. BMS might be better approached as a neurological condition rather than a pain-related condition;
3. Clonazepam (used as an oral mouthwash in the study) acts by enhancing the inhibitory effect of GABA on pain receptors;
4. Clonazepam promotes the serotonin-mediated pain inhibition

From these, one can draw connections between BMS and GABA, serotonin, and hormonal dysregulation in general. Not to say these are the cause of BMS—just that they may prove useful in describing the pathology of some BMS cases.

I would like to emphasize that antidepressants have been known to cause salivary gland dysfunction that contributes to BMS as well (3). What works for one may not work for another. One possible alternative would be supplementation with serotonin-increasing supplements like 5-HTP. Just as with any supplementation, there are factors to consider there as well.

Anticonvulsants

A randomized, double-blind, placebo-controlled study found that the combination of Gabapentin and Alpha-Lipoic Acid provided relief to those suffering from BMS in 70% of cases, among 120 participants (12). This represented a 13.2x better chance of improvement compared to placebo and nearly doubled-chance compared to either intervention (Gabapentin vs. ALA) as a single therapy. See the below chart for a visual comparison.

Crowd-Sourcing an Understanding

From here on, I’ll be attempting to bring together a sort of resource from which (with the help of readers like you) a functional understanding of BMS may emerge. If you or someone you know suffers from BMS please reach out, share your experience, and offer any insights you may have. Just use our contact form to pass along your message.

Review

Burning Mouth Syndrome is a medical condition that varies greatly in how it presents among individuals. The different subtypes hint this condition may result from a wide range of potential causes. Globally, BMS affects millions. Still, researchers struggle to develop treatment options to effectively address the symptoms or cause of BMS.

While there are no official known treatments or causes of BMS there are a number of emerging theories. These theories, often distilled from the knowledge of small practices or individual practitioners, are still regarded as initial reports currently. One should always speak with their physician before considering such options. One thing I always keep in mind—symptoms can always get worse.

References

1. Biadsee, Ameen, et al. “Olfactory and Oral Manifestations of COVID-19: Sex-Related Symptoms—A Potential Pathway to Early Diagnosis.” Otolaryngology–Head and Neck Surgery, vol. 163, no. 4, Oct. 2020, pp. 722–728, doi:10.1177/0194599820934380.
2. Sanders, Richard D. “The Trigeminal (V) and Facial (VII) Cranial Nerves: Head and Face Sensation and Movement.” Psychiatry (Edgmont (Pa. : Township)) vol. 7,1 (2010): 13-6. PMID: PMC2848459.
3. Mitsikostas, Dimos D et al. “Refractory burning mouth syndrome: clinical and paraclinical evaluation, comorbidities, treatment, and outcome.” The journal of headache and pain vol. 18,1 (2017): 40. doi:10.1186/s10194-017-0745-y.
4. Jedel, Elizabeth et al. “Differences in personality, perceived stress and physical activity in women with burning mouth syndrome compared to controls.” Scandinavian journal of pain vol. 21,1 183-190. 28 Oct. 2020, doi:10.1515/sjpain-2020-0110.
5. McMillan, Roddy et al. “Interventions for treating burning mouth syndrome.” The Cochrane database of systematic reviews vol. 11,11 CD002779. 18 Nov. 2016, doi:10.1002/14651858.CD002779.pub3.
6. Bergdahl, M, and J Bergdahl. “Burning mouth syndrome: prevalence and associated factors.” Journal of oral pathology & medicine: official publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology vol. 28,8 (1999): 350-4. doi:10.1111/j.1600-0714.1999.tb02052.x.
7. Kohorst, John J et al. “A population-based study of the incidence of burning mouth syndrome.” Mayo Clinic proceedings vol. 89,11 (2014): 1545-52. doi:10.1016/j.mayocp.2014.05.018.
8. Kohorst, J J et al. “The prevalence of burning mouth syndrome: a population-based study.” The British journal of dermatology vol. 172,6 (2015): 1654-1656. doi:10.1111/bjd.13613.
9. Scala, A., Checchi, L., Montevecchi, M., Marini, I., & Giamberardino, M. A. (2003). Update on Burning Mouth Syndrome: Overview and Patient Management. Critical Reviews in Oral Biology & Medicine, 14(4), 275–291. doi:10.1177/154411130301400405.
10. Biadsee, Ameen, et al. “Olfactory and Oral Manifestations of COVID-19: Sex-Related Symptoms—A Potential Pathway to Early Diagnosis.” Otolaryngology–Head and Neck Surgery, vol. 163, no. 4, Oct. 2020, pp. 722–728, doi:10.1177/0194599820934380.
11. Mitsikostas, Dimos D et al. “Refractory burning mouth syndrome: clinical and paraclinical evaluation, comorbidities, treatment, and outcome.” The journal of headache and pain vol. 18,1 (2017): 40. doi:10.1186/s10194-017-0745-y.
12. López-D’alessandro, E, and L Escovich. “Combination of alpha-lipoic acid and gabapentin, its efficacy in the treatment of Burning Mouth Syndrome: a randomized, double-blind, placebo-controlled trial.” Medicina oral, patologia oral y cirugia bucal vol. 16,5 e635-40. 1 Aug. 2011, doi:10.4317/medoral.16942.
13. Dias Fernandes, Carolina Sommer et al. “Salivary dehydroepiandrosterone (DHEA) levels in patients with the complaint of burning mouth: a case-control study.” Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics vol. 108,4 (2009): 537-43. doi:10.1016/j.tripleo.2009.06.022.
14. Femiano, Felice et al. “Burning mouth syndrome and burning mouth in hypothyroidism: proposal for a diagnostic and therapeutic protocol.” Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics vol. 105,1 (2008): e22-7. doi:10.1016/j.tripleo.2007.07.030.