The pharmacist’s role in optimising care for adults with trigeminal neuralgia

Introduction

Trigeminal neuralgia (TN) is a severe chronic condition that causes neuropathic facial pain. It can have a profound impact on quality of life, including nutrition, employment, mental wellbeing and social functioning^​1​. It is classically characterised by sudden, brief episodes of intense, electric shock–like pain affecting one or more divisions of the trigeminal nerve, often triggered by routine activities such as talking, chewing, brushing the teeth, washing the face or exposure to light touch or cold air^​2–4​.

Although TN is relatively uncommon, the results of UK primary care studies suggest that it is diagnosed in around 8 to 27 per 100,000 people each year, with a lifetime prevalence of approximately 0.7 per 1,000^​5​. Delayed recognition and misdiagnosis of TN are common, particularly in primary care and dental settings, leading to prolonged suffering and inappropriate treatment^​6,7​. Pharmacists across all sectors can contribute to earlier recognition, medicines optimisation and patient support.

Additional insight for this article was sought from members of the Trigeminal Neuralgia Association (TNA). Patients shared their experiences of diagnosis, treatment and day-to-day challenges, as well as their views on how pharmacy professionals could better support them as part of multidisciplinary care. Anonymised quotations are included throughout to illustrate important themes and ground recommendations in patient lived experience.

Epidemiology and risk factors

TN usually affects people aged over 50 years and is more common in women^​5,6​. Underlying neurological conditions — particularly multiple sclerosis — significantly increase risk and are an important cause in younger patients^​5,8​. Although rare, cases in children and adolescents have been described^​9​.

An interplay of biological (e.g. neurovascular compression, multiple sclerosis, genetics), environmental (e.g. climatic triggers, vascular comorbidities) and epidemiological factors (e.g. population ageing, better recognition) is thought to contribute to the rising prevalence of TN^​1,2​. 

Pathophysiology and classification

The trigeminal nerve is the fifth cranial nerve and provides sensory innervation to the face (see Figure 1). TN can be classified as idiopathic, classical and secondary subtypes based on clinical and imaging findings^​10​.

Figure 1: Trigeminal nerve distribution

Idiopathic TN is where no underlying structural or secondary cause can be identified on clinical assessment or imaging. It presents with the typical pattern of sudden, severe, unilateral, electric shock‑like facial pain attacks in one or more trigeminal nerve divisions but without demonstrable neurovascular compression, demyelinating disease or other pathology^​3,11​.

Classical TN, which is the most common type, is thought to result from neurovascular compression of the trigeminal nerve root near the brainstem, leading to focal demyelination and increased nerve excitability. This mechanism is believed to explain the paroxysmal, shock‑like nature of the pain^​12​.

Secondary TN arises from identifiable underlying pathology such as multiple sclerosis-related demyelination or structural lesions such as tumours. These mechanisms differ from classical TN and have important implications for investigation and management. This is why neuroimaging is recommended when presentations are atypical or red‑flag features are present^​2,3,13​.

Clinical features and differential diagnosis

TN is primarily a clinical diagnosis based on a characteristic symptom pattern^​2​. The National Institute for Health and Care Excellence defines TN as recurrent, unilateral paroxysms of facial pain that last from a fraction of a second up to two minutes, affecting one or more trigeminal divisions^​5​. The pain is severe, stabbing or electric in quality, triggered by stimuli, stereotyped for the individual and occurs in the absence of neurological deficit^​11​.

Diagnosis can be challenging because TN shares features with other conditions affecting the face and oral cavity^​2​. Some of the important differentials include dental pain, post‑herpetic neuralgia, temporomandibular disorders, sinus disease, cluster headache and atypical facial pain^​3,14​.

Practical screening questions for a pharmacist

Using national TN guidance with peer‑reviewed descriptions of dental pain^{​5,15–17​}, important historical features typical of each condition can be determined. Although no single TN screening tool has been identified for use in primary care^​18​, these features can be used to develop practical screening questions that may support pharmacists in community, urgent care or telephone triage settings. Examples are summarised in Table 1^{​5,15–17​}.

Table 1: Screening questions to differentiate trigeminal neuralgia from dental pain

Red‑flag features requiring urgent specialist referral and neuroimaging include sensory loss, motor weakness, bilateral symptoms, pain persisting between attacks, onset before the age of 40 years, progressive symptoms or features suggestive of secondary causes such as multiple sclerosis or neoplasia^​1,3,11​.

Pharmacological management

Management of TN is primarily pharmacological, with escalation to surgical intervention considered when medicines are ineffective or poorly tolerated^​2,19​. Treatment decisions are usually specialist‑led, but pharmacists play an important role in optimisation and monitoring.

National guidelines identify anticonvulsants as first‑line therapy^​3,5,13​. Carbamazepine and oxcarbazepine are recommended initially, with alternatives, such as lamotrigine, gabapentin and pregabalin, used as add‑on or second‑line options. Baclofen and botulinum toxin A may be considered in selected cases^{​3,11,19​}.

Oxcarbazepine is a structural analogue of carbamazepine. It is not licensed for use in the UK but is used off label if contraindications to carbamazepine exist^​3,15​. 

For the purposes of this article, focus is placed on carbamazepine, which remains the only licensed treatment for TN in the UK.

Carbamazepine: safety and monitoring

Carbamazepine is an effective drug but presents several challenges for long‑term management^​3​. At initiation, it has a narrow therapeutic range and undergoes autoinduction, with enzyme induction reducing serum concentrations during the first two to four weeks of treatment^​20​. As a strong enzyme inducer, carbamazepine can reduce the effectiveness of hormonal contraceptives, anticoagulants and many other medicines^{​21–23​}. Therefore, pharmacists should routinely ask about all prescribed, over-the-counter and herbal products, warn patients about contraception failure risk and encourage them to seek advice before starting any new medicine or supplement^​24​.

The results of a study published in 2021 suggest that while carbamazepine is effective for most people with TN, adverse effects are common — for example, in one cohort of 354 patients, 43.6% experienced side effects, while almost 30% required dose reduction or treatment interruption owing to tolerability issues^​25​.

Before starting treatment, a baseline assessment must be undertaken, including full blood count and liver function tests, particularly in patients with a history of liver disease and in older patients. Baseline renal function, serum sodium and BMI should also be checked. In patients with known cardiac history, an ECG should be considered^​20​. Genetic screening for the HLA‑B*1502 allele is recommended in individuals of Han Chinese or Thai origin owing to the risk of severe cutaneous adverse reactions such as Stevens–Johnson syndrome^​20,22​. Based on clinical judgement, clinicians may also consider baseline screening of serum creatinine, iron, reticulocytes and vitamin D levels for patients with pre-existing conditions, insufficient calcium intake or who are housebound^​23,26​.

Although carbamazepine carries a lower teratogenic risk than valproate and is not currently subject to a formal pregnancy prevention programme, females of childbearing potential should still receive structured counselling about pregnancy risks and contraceptive interactions^{​27–29​}. Patients should also be signposted to seek specialist advice regarding highly effective, non‑interacting contraception, such as an IUD, IUS or contraceptive injection^​30,31​. Medicines and Healthcare products Regulatory Agency safety alerts highlight risks relating to suicidal ideation^​32​, pregnancy exposure^​29​  and switching between manufacturers^​23​.

For the management of paroxysmal pain in TN, carbamazepine should be started at 200mg daily and increased at a minimum of three-day intervals as per national guidance or the British National Formulary^​22,23​. Slower dose increases may be indicated depending on patient response. A guide, published in Practical Neurology, recommends a maximum dose for paroxysmal pain in TN as 1,200mg per day^​3​. Once pain is stable, the dose may be tapered to the lowest tolerable level and increased again when needed^​5​.

Monitoring

Routine carbamazepine plasma concentration monitoring is not recommended unless clinically indicated. Hyponatraemia occurs in around 26% of patients and may be mistaken for medication side effects. It is usually mild, but close monitoring is advised, as dose reduction or withdrawal may be required depending on symptom severity, duration and hydration status^​33​. Common adverse effects include drowsiness, dizziness, diplopia, hyponatraemia and cognitive impairment, all of which may affect safety and adherence^​20,23​. Therefore, patients should be counselled regarding driving and machinery use, particularly during titration^​22​.

Monitoring should include a follow‑up at two weeks after starting the medication, then monthly for the next three months. The Specialist Pharmacy Service advises sodium checks in patients with renal impairment or those taking diuretics, which are known to lower sodium levels. Patients who struggle with tolerability may benefit from switching to a modified‑release formulation or dose splitting^​20​.

Follow‑up and long-term management

When counselling patients with TN, it is essential to take a holistic approach and address oral health, diet, mental wellbeing and access to support alongside medication management^​34,35​. Psychological distress is common in TN, with high rates of anxiety, depression and suicidal ideation reported^​6,32​. The biopsychosocial model may provide a more comprehensive framework than a purely biomedical approach, as pain is shaped not only by biological pathology but also by psychological factors, such as mood, expectations and coping strategies, and by social circumstances including isolation, work pressures and availability of support^{​36–38​}.

This is particularly important for patients experiencing low mood or anxiety, which may contribute to social withdrawal and increase the risk of suicidal ideation or suicidal behaviour^{​6,34,39​}. When combined with potential adverse effects of carbamazepine, these factors warrant careful monitoring.

Ongoing review should include the assessment of pain control, adverse effects and potential drug interactions. This is especially important in secondary TN, where patients may already be taking multiple medicines for conditions such as multiple sclerosis^​5​.

Patient counselling and support

Acute TN flare ups differ from other pain presentations, and paracetamol, non‑steroidal anti‑inflammatory drugs and opioids are frequently ineffective during severe attacks^​40​. During these episodes, patients may be unable to speak, so it may be helpful to advise them to carry a notebook and pen to communicate symptoms^​4​. An alternative is an alert card, such as the sunflower lanyard card available through the TNA^​41​, which can be used to communicate emergency care needs, including urgent dental or emergency department referral. In some settings, interventions, such as local anaesthetic nerve block, may also be available^​4​.

Anticipation of pain attacks can heighten anxiety and may itself act as a trigger, creating a cycle that contributes to social withdrawal^​34,36​. For individuals whose pain is provoked by light touch or close contact, intimacy may become difficult, affecting relationships and overall wellbeing^{​6,13,42​}.

Non‑pharmacological approaches, such as mindfulness and meditation, may help reduce stress and improve emotional regulation. Those approaches can be useful adjuncts for some patients^{​36,37,39​}. Complementary therapies, such as acupuncture, have also been explored. Although evidence remains limited, the results of several studies suggest potential benefit when used alongside standard treatment^​43​.

Practical adaptations can also help reduce symptom burden^​4​. Pharmacists can advise on modified dental care, such as soft‑bristled toothbrushes and non‑irritating toothpaste or mouthwash, to minimise oral stimulation and reduce triggers^​44​.

Patients should also be signposted to supportive resources. In the UK, the TNA offers specialist‑led education, a helpline and local peer groups, which can be invaluable for individuals who feel isolated and may help improve coping and engagement with care^​41​.

Future therapies

Research continues to expand future treatment options. Agents, such as vixotrigine, have shown early promise but have not progressed to phase III trials^​45​, while compounds, such as basimglurant, are currently in phase II studies^​46​. 

The role of pharmacy professionals 

Although TN is usually managed within specialist services, pharmacists play an important role in optimising patient care across primary and secondary settings. Main responsibilities include the early identification of red‑flag symptoms requiring referral, medicines optimisation and management of drug–drug interactions, as well as support with safe dose titration and adherence. Pharmacists are also well placed to monitor and manage adverse effects, address the psychological impact of chronic facial pain, and signpost patients to appropriate specialist services and patient support organisations. 

Conclusion

By combining clinical vigilance with patient‑centred care, pharmacy professionals can make a meaningful difference for people living with this debilitating condition.

As emphasised by Aneeta Prem, chief executive of TNA UK: “TN is not only about pain control. It is about whether a person can function, stay safe and maintain daily life. That is why awareness in pharmacy matters.”