When Medication Is Part of the Swallowing Problem

Most discussions of dysphagia and medication focus on how patients take their drugs. An equally important question is whether the drugs themselves are contributing to swallowing difficulty. A substantial number of commonly prescribed medications — particularly in elderly and neurologically impaired patients — have pharmacological effects that directly impair swallowing.

This is clinically relevant because:

• Iatrogenic (medication-induced) dysphagia is often reversible when the offending drug is reduced or replaced
• Multiple drugs with swallowing-impairing effects may be prescribed simultaneously, creating additive impairment
• In Hong Kong’s elderly care setting, polypharmacy is common and medication review is often underutilised as a dysphagia intervention

Mechanisms by Which Drugs Impair Swallowing

Reduced Saliva Production (Xerostomia)

Adequate saliva is essential for bolus formation and for lubricating the oral and pharyngeal surfaces during swallowing. Reduced saliva makes food harder to chew and form into a coherent bolus, and dry mucosa increases friction during pharyngeal transit.

Drug classes causing reduced saliva:

• Anticholinergic drugs — the most significant category; see below
• Antihistamines (first generation: chlorphenamine, promethazine)
• Tricyclic antidepressants (amitriptyline, nortriptyline)
• Diuretics (systemic dehydration reduces saliva)
• Antihypertensives (some)
• Opioid analgesics

Reduced Neuromuscular Coordination

Swallowing involves precisely coordinated sequential muscle contractions across more than 30 muscles. Any drug that affects neuromuscular transmission, motor coordination, or muscle tone can impair this coordination.

Drug classes affecting neuromuscular function:

• Neuroleptics / antipsychotics — cause drug-induced parkinsonism, akathisia, tardive dyskinesia; all of these can impair pharyngeal motor function
• Benzodiazepines — muscle relaxant and sedative effects reduce pharyngeal muscle tone and coordination
• Opioid analgesics — sedation and reduced reflexes
• Anticonvulsants (some, at higher doses) — motor incoordination as a side effect

Reduced Level of Consciousness or Alertness

Adequate arousal is required for safe swallowing. Drugs that reduce consciousness or alertness impair the patient’s ability to coordinate swallowing safely.

Drug classes causing sedation:

• Benzodiazepines
• Opioids
• Some antiepileptics
• First-generation antihistamines
• Some antipsychotics

Oesophageal Dysmotility

Some drugs slow oesophageal peristalsis or reduce lower oesophageal sphincter tone, leading to delayed transit of food and medications through the oesophagus to the stomach.

Drug classes affecting oesophageal motility:

• Calcium channel blockers (particularly nifedipine, diltiazem) — reduce oesophageal smooth muscle tone
• Anticholinergic drugs — reduce oesophageal peristalsis

Key Drug Classes: Detailed Profiles

Anticholinergic Drugs

Anticholinergic drugs block muscarinic acetylcholine receptors, reducing smooth muscle tone and glandular secretion throughout the body. Their effects on swallowing are multi-layered:

• Reduced saliva — impairs bolus formation and oral clearance
• Reduced oesophageal peristalsis — slows oesophageal transit
• Reduced pharyngeal contractility (at higher doses)
• Central sedation (crosses blood-brain barrier in many formulations)

Drugs with significant anticholinergic burden in common use in Hong Kong:

The Anticholinergic Burden Score: Research shows that the cumulative anticholinergic burden from multiple low-potency drugs can be clinically significant. An elderly patient on oxybutynin, amitriptyline, and promethazine may have a combined burden that substantially impairs swallowing, cognition, and bowel function.

Alternatives for bladder management: For patients on anticholinergics for overactive bladder, beta-3 adrenergic agonists (e.g., mirabegron) have a significantly lower anticholinergic burden and are available in Hong Kong. Discuss with the prescribing urologist or geriatrician.

Neuroleptics (Antipsychotics)

Both typical (first-generation) and atypical (second-generation) antipsychotics can impair swallowing through several mechanisms:

Typical antipsychotics (haloperidol, chlorpromazine): Higher risk of drug-induced parkinsonism, akathisia, and tardive dyskinesia — all of which can impair pharyngeal motor function and reduce the efficiency of the pharyngeal swallow.

Atypical antipsychotics (risperidone, quetiapine, olanzapine): Lower risk of extrapyramidal effects but significant sedation (particularly olanzapine and quetiapine), which reduces swallowing coordination. Risperidone, despite being “atypical,” has relatively higher extrapyramidal risk among second-generation agents.

Tardive dysphagia: A recognised but underdiagnosed complication of long-term neuroleptic use, characterised by abnormal oropharyngeal movements that directly interfere with bolus control and safe swallowing. Consider this in any patient on long-term antipsychotics who develops or worsens dysphagia.

In Hong Kong’s residential care context: Antipsychotics are frequently prescribed for dementia-related behavioural symptoms in RCHE residents. This is a known risk population for medication-related dysphagia. Request a medication review and SLP assessment if a resident on antipsychotics develops new or worsening dysphagia.

Calcium Channel Blockers

Calcium channel blockers (CCBs) are widely used for hypertension and cardiac conditions. Their effect on smooth muscle extends beyond blood vessels to the oesophagus:

• Reduced lower oesophageal sphincter pressure → increased reflux
• Reduced oesophageal peristaltic amplitude → impaired clearance of food residue

Common CCBs in Hong Kong: amlodipine, nifedipine, diltiazem, verapamil

Clinical significance: For patients already experiencing oesophageal dysmotility or who aspirate oesophageal contents, CCBs may worsen the situation. Discuss with the cardiologist whether alternative antihypertensive agents (e.g., ACE inhibitors, ARBs, beta-blockers) are appropriate for that specific patient.

Sedatives and Benzodiazepines

Benzodiazepines (diazepam, lorazepam, alprazolam, temazepam, midazolam) have multiple mechanisms that impair swallowing:

• Central sedation → reduced alertness → impaired swallowing coordination
• Muscle relaxation → reduced pharyngeal muscle tone
• Reduced cough reflex → impaired protective mechanism

In elderly patients, benzodiazepine clearance is prolonged (reduced hepatic metabolism and renal clearance) — a patient taking a “standard” dose may be substantially more sedated than a younger patient and for longer.

Requesting a Medication Review in Hong Kong

Public Sector Pathway

If you suspect a patient’s swallowing has worsened since starting or increasing a medication dose:

1. Raise this at the next outpatient appointment — explain specifically which medication change preceded the swallowing deterioration and over what timeframe
2. Request a clinical pharmacist review — available through HA hospital pharmacy departments
3. If the patient is in a RCHE, the centre’s nurse or care manager can initiate a referral to the patient’s GP or geriatrician for a medication review

Private Sector Pathway

• Raise concerns at the next GP or specialist appointment
• Some private geriatric clinics in Hong Kong offer comprehensive medication review as a specific service
• Clinical pharmacists in private hospitals can also conduct medication review — usually requires a physician referral

The Medication Review Request

When requesting a medication review for swallowing concerns, be specific:

• State which specific drugs are suspected of contributing
• Describe how and when swallowing changed
• Bring a complete and current medication list to the appointment
• Mention any known aspiration events or chest infections

Frequently Asked Questions

Q: The patient has been on the same medications for years. Could they suddenly cause swallowing problems?

A: Yes. Swallowing-impairing drug effects are dose-dependent and interact with the patient’s overall health. A patient whose swallowing was adequate when younger may cross a threshold into clinically significant dysphagia as: (1) other health conditions progress, (2) cumulative drug load increases as new medications are added, or (3) ageing reduces physiological reserve. The drug dose that was manageable at 70 may be problematic at 80.

Q: Is it safe to ask the doctor to reduce a psychiatric medication?

A: Any change to psychiatric medication should be discussed with the prescribing psychiatrist or geriatric psychiatrist. Abrupt withdrawal of antipsychotics or benzodiazepines can cause rebound effects. The goal is a supervised dose reduction or switch to a safer alternative — not unilateral discontinuation.

This page provides educational information. All medication changes must be discussed with and authorised by the prescribing physician. Do not stop or reduce any medication without medical guidance.