Burning Mouth Syndrome

Burning Mouth Syndrome is a chronic OFP condition, characterised by a burning and painful sensation of the oral mucosa, usually on the anterior two-third or tip of the tongue (see video above and lecture notes). The ICOP categorised BMS as idiopathic condition, however, there is a good evidence supporting its neuropathic aetiology (“International Classification of Orofacial Pain, 1st edition (ICOP). The ICOP (see link) defined BMS as “an intraoral burning or dysaesthetic sensation, recurring daily for more than 2 hours per day, lasting for more than 3 months, without evident causative lesions on clinical examination and investigation” and divided it into BMS with or without somatosensory changes.

Burning mouth symptoms can be due to:

  • Primary Burning mouth syndrome MS – also known as unknown cause/ idiopathic or essential BMS.
  • Secondary BMS known as Burning mouth disorder BMD – which is caused by local factors or an existing systemic condition.

The main causes for BMS/BMD are shown in the table below:

Most common triggers of BMS
Dry mouth (xerostomia) Can be due to medications, health problems, salivary gland dysfunction, or chemotherapy.
Wearing dentures Allergies to materials used in dentures, poor denture fit, and putting stress on muscles.
Excessive mouth irritation Due to overbrushing the tongue, high consumption of acidic drinks, overuse of mouthwash or usage of abrasive toothpaste or medication.
Oral parafunctional habits Such as grinding teeth, biting, or thrusting the tongue, or sucking the cheek (oral linea alba).
Other oral conditions Such as candida infections, geographic tongue, or lichen planus.
Allergic reaction Such as allergies to medications, foods, food flavourings, dyes, dental materials, or others.
Nutritional deficiency Deficiency of vitamins and minerals such as Iron, Zinc, Vitamin B1 (thiamine), Vitamin B2 (riboflavin), Vitamin B6 (pyridoxine), Vitamin B9 (folate) or Vitamin B12 (cobalamin).
Hormonal imbalance Such as loss of hormone during menopause, or reduced plasma oestrogens.
Endocrine disorders Such as diabetes and hypothyroidism.
Immunological diseases Such as Sjogren’s syndrome or Lichenoid reaction.
Medical disease gastrointestinal reflux disease, Parkinson disease or multiple sclerosis (MS).
Medication Such as medication used to treat high blood pressure, antihistamines, or benzodiazepines.
Nerve damage Damage to the nerves that regulate pain and taste in the tongue.
Psychological factors Such as stress, anxiety, depression or eating disorders.
This table was adapted from Aggarwal and Panat (2012); Tan and Renton (2020);
Vadivelu, Vadivelu, and Kaye (2014)

Types of BMS have been described by Lamey et al (see table below) however the accepted types are now International Classification Orofacial Pain BMS with or without mechanosensory changes (altered sensation or poor working sensory nerves on the tongue surface

Lamey and Lewis (1989) also used pain intensity to classify BMS into three types:
· Type I – Patients wake up with no pain and the pain increases gradually during the day.
· Type II – Patients are awakened by a burning sensation and pain and experience symptoms throughout the day and night. These patients find it difficult to sleep at night, this also alters an individual’s mood and dietary habits and reduces social activity.
· Type III – Patients have irregular burning sensation and pain. Their symptoms can be associated with an allergic reaction to food additives.

The main symptom of BMS is a burning and scalding sensation of the oral and tongue mucosa; it can also present itself with xerostomia, numbness, loss of taste or altered taste (National Institute of Dental and Craniofacial Research, 2019). In line with a recent update on BMS by Tan and Renton (2020), 73% of patients with BMS suffered from scalding, tingling, or numbness of the oral mucosa. As Coculescu, Radu, and Coculescu (2014) stated headaches, thirst, pain in the temporomandibular joint (TMJ), neck, shoulders, and suprahyoid muscle can also be secondary symptoms of BMS. Pain is usually bilateral and lasts for years. It can vary from day to day; patients may have constant pain throughout the day, or their pain intensity may alter across the day (Renton, 2011).

Prevalence According to Cerchiari et al. (2006), BMS is more common in women with a prevalence of 5.5% in women and 1.6% in men. BMS mainly presents in middle age and elderly women and impairs eating, drinking and daily activities (Renton, 2011). Zakrzewska (2009) stated that the loss of hormones during menopause can increase the risk of BMS in women. The prevalence of BMS after menopause according to Zakrzewska and Buchanan (2016) is 18-33%.

Diagnosis of BMS is difficult due to the lack of any specific standard diagnostic tests (National Institute of Dental and Craniofacial Research, 2019). The pathophysiology of BMS is unclear, however, there is a high possibility that it has a neuropathic origin (Liu et al., 2018). During the last 10 years many studies conducted on the neuropathic background of BMS, the results of these studies showed the involvement of peripheral small fibre neuropathy, trigeminal neuropathy, or chorda tympani hypofunction in patients with BMS. Another cause of BMS can be a decreased level of dopamine in the brain of patients with psychiatric disorders (Ślebioda, Lukaszewska-Kuska, & Dorocka-Bobkowska, 2020). However, a recent IMMPACT-recommended outcome measures and tools of assessment in burning mouth syndrome RCTs: an international Delphi survey protocol recommends specific protocol for diagnosis of BMS.

Dentists and doctors can diagnose BMS by reviewing the patient’s medical, dental, and psychological history and by carrying out a clinical examination. However, in the absence of any clinical evidence, such as the geographic tongue, coated tongue, or exfoliative glossitis, BMS can be a secondary condition caused by systematic disorders such as diabetes or chronic vitamin deficiency (Coculescu et al., 2014). Analysing symptoms is essential in the diagnosis of BMS; these symptoms include burning sensation in the mouth, numbness, tingling, dry mouth, thirst, loss of taste, taste disturbance, more intense pain as the day progresses and less or more pain while eating (Milkov, Tonchev, & Nedev, 2013; Vadivelu et al., 2014). Figure 2 illustrates the diagnosis of BMS. There are some diagnostic tests beneficial in the diagnosis of BMS (see table below).

Further tests in the diagnosis of BMS
Blood tests Check blood count, glucose level, thyroid function, nutritional factors, and immunity
Allergy tests Find out the presence of allergies to any foods, additives, or materials used in dentures or dental restorations
Oral cultures Biopsies from the mouth can lead to determining bacterial, fungal, or viral infections
Imaging Such as a magnetic resonance imaging (MRI) or computerised tomography (CT) scan determine other health problems
Salivary measurements To check if there is decreased salivary flow
Gastric reflux test To diagnose gastroesophageal reflux disease
Psychological questionnaire To recognise the presence of anxiety, depression, or other mental health issues
Medical adjustment Dose alteration or to change medication
This table was adapted from Coculescu et al. (2014); Vadivelu et al. (2014)

Treatment Tu et al. (2019) stated that the heterogeneous nature of BMS has prevented developing a standardised therapy for BMS. However, according to the National Institute of Dental and Craniofacial Research (2019) doctors and dentists are able to prescribe medications to improve the symptoms of BMS. The treatment aims to control the pain and improve the symptoms of BMS; however, the background of this syndrome is unclear, meaning there is still no effective and definitive treatment (de Souza, Mármora, Rados, & Visioli, 2018; Ślebioda et al., 2020). Patients respond greatly to long-term treatment (Jimson, Rajesh, Krupaa, & Kasthuri, 2015). Identifying the type of BMS is the first step in treating BMS patient (Gurvits & Tan, 2013). Current treatment of BMS is based on the patients’ symptoms and any related underlying conditions (Vadivelu et al., 2014). Furthermore, Jimson et al. (2015) suggested that if there is any local, systematic, or psychological factors, they should be eliminated or treated first. This study also stated that BMS can be treated by topical medications, systematic medication, or behavioural interactions. BMS patients could be advised to avoid tobacco, alcohol, acidic drinks, spicy foods, alcohol mouthwash or abrasive toothpaste (Nasri-Heir, Zagury, Thomas, & Ananthan, 2015). We have recently published a systematic review of treatment for BMS.

The most effective treatments for BMS are;

Cognitive behavioural therapy CBT is one of the effective nonpharmacological therapies. Research showed that this approach improves the BMS pain and discomfort for 6-12 months, however, a long course of treatment (12-16 sessions) is expensive and unaffordable for most patients (Tu et al., 2019). In contrast to this, group psychotherapy sessions can be an alternative due to their cost-effectiveness (Miziara, Filho, Oliveira, & Rodrigues dos Santos, 2009). Acupuncture is a technique applied in traditional Chinese medicine that can be used to manage chronic pain (Cheung & Trudgill, 2015). The study by Scardina, Ruggieri, Provenzano, and Messina (2010) demonstrated significant improvements in the burning sensation after 3 weeks of acupuncture; the improvement caused by acupuncture was shown to last for 18 months.

Nortriptyline Nortriptyline, a Tricyclic antidepressant (TCA), is also effective in reducing pain in patients with BMS due to its analgesic action (Fenelon, Quinque, Arrive, Catros, & Fricain, 2017). However, amitriptyline is related to adverse effects, such as drowsiness, xerostomia, weight gain and constipation, making it less tolerable for patients (Suga et al., 2019). In this case, gabapentin can be prescribed. Gabapentin can cause same adverse effects; however, the risk of addition is low, and some patients may tolerate it better (White, Kent, Kurtz, & Emko, 2004).

Topical Clonazepam The 2 types of treatment for BMS are pharmacological and nonpharmacological therapies. BMS is associated with psychological disorders, therefore, antidepressants, benzodiazepines and psychotherapy can be used to manage this syndrome (Reyad, Mishriky, & Girgis, 2020). Topical clonazepam is considered as the first line therapy in patients with BMS; it improves the BMS pain, although just like any other benzodiazepines its effects is short term. It is topical as it can be associated with addiction (Heckmann, Kirchner, Grushka, Wichmann, & Hummel, 2012; Tu et al., 2019; Wright, 2020).

Other less effective strategies    Alpha-lipoic acid, laser therapy, Cognitive Behavioural Therapy (CBT), and acupuncture are other treatments for BMS. These alternative treatments can be beneficial for patients that cannot tolerate the adverse effects of amitriptyline or clonazepam (Tan & Renton, 2020). Nasri-Heir et al. (2015) stated that the combination therapy is more effective in treating BMS symptoms. According to a randomised controlled trial (RCT) by López-D’alessandro and Escovich (2011), administration of alpha-lipoic acid and gabapentin together showed a great reduction in pain compared to using any of these drugs alone.

A pilot study by Heckmann, Heckmann, Ungethüm, Hujoel, and Hummel (2006) presented opposite results with regards to administrating gabapentin, only having a small or no effect on improving BMS symptoms.

Furthermore, the results of the RCT by Barbosa et al. (2018) suggested that alpha-lipoic acid and low-level laser therapy are both effective in stimulating saliva flow and managing symptoms of BMS, though low-level laser therapy showed more effectiveness. There is limited evidence for CBD oil in BMS but increasingly patients are reporting effectiveness ins some cases.

Treatment advice sheets

Nortriptyline dose advice link 7

Clonazepam dose advice information sheet  and information on cannabidiol.

BMS Infomation sheet here.

A recent article outlines advice for patients with BMS