Doctors Revision

Antitussives: Opioid, Non-opioid, Peripheral Cough Suppressants, Doses & Emergency Use

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Safety first: A cough is a protective airway reflex. Before suppressing it, identify and treat the cause. Do not use a cough suppressant to delay assessment of severe breathlessness, cyanosis, stridor, choking, altered consciousness, haemoptysis, chest pain, hypoxia, a silent chest, suspected foreign body, or rapidly worsening illness. Opioid antitussives can depress ventilation, and suppressing an effective productive cough can retain infected or obstructing secretions.

Antitussives: complete pharmacology, dosing and emergency clinical use

Antitussives are medicines that reduce the frequency or intensity of coughing. They are most useful for a distressing, non-productive (dry) cough after the clinician has considered important causes such as asthma, pneumonia, tuberculosis, gastro-oesophageal reflux, post-nasal drip, heart failure, pulmonary embolism, medication effects (especially ACE inhibitors), environmental irritants, and foreign-body aspiration. They are symptomatic medicines: they do not eradicate infection, reverse bronchospasm, remove a foreign body, or replace airway clearance.

Core distinction: an antitussive suppresses the cough reflex; an expectorant (for example guaifenesin) aims to make secretions easier to expel; a mucolytic (for example acetylcysteine or bromhexine) changes mucus structure or viscosity. Do not automatically combine a cough suppressant with a large burden of secretions.

Learning objectives

  • Explain why cough is protective and locate the principal peripheral and central components of the cough reflex.
  • Classify centrally acting opioid and non-opioid agents, peripherally acting agents, demulcents, expectorants and mucolytics.
  • Describe the mechanism, indications, contraindications, doses, adverse effects, interactions, monitoring and toxicity management of major antitussives.
  • Choose when suppression is reasonable and when cough must be preserved for airway clearance.
  • Recognise opioid respiratory depression, dextromethorphan toxicity and serotonin syndrome as emergencies.

1. Cough physiology: why suppression can help or harm

Cough is a coordinated defensive reflex that removes mucus, aspirated material and irritant particles from the larynx, trachea and bronchi. It begins when mechanical or chemical receptors are stimulated. Afferent impulses travel mainly through the vagus nerve; sensory input from the nose, pharynx, larynx and ear also travels through trigeminal, glossopharyngeal and superior laryngeal pathways. The medullary and pontine cough network integrates the signal, and efferent output activates the laryngeal muscles, diaphragm, intercostal muscles and abdominal muscles.

Phase What happens Clinical relevance
Inspiratory phase A deep inspiration increases the volume of gas available for expulsion. A weak or sedated patient may never generate the inspiratory volume needed for an effective cough.
Compressive phase The glottis closes while expiratory and abdominal muscles contract, creating high intrathoracic pressure. Opioids, neuromuscular weakness and severe fatigue reduce force generation.
Expulsive phase The glottis opens suddenly; high-velocity airflow shears mucus and particles from airway walls. Suppressing a wet cough can leave secretions in the bronchi and worsen atelectasis or infection.

Classifying the symptom before choosing a drug

Dry, irritating cough

Little or no sputum; may disturb sleep or cause chest-wall pain. After red flags and causes are addressed, a short course of a non-opioid antitussive or a carefully selected opioid may be considered.

Productive cough

Expectoration is part of treatment. Encourage hydration, physiotherapy, bronchodilation when indicated, mucolytic therapy in selected diseases and treatment of infection or inflammation. Suppress only for a clear, time-limited reason.

Paroxysmal or unusual cough

Think pertussis, asthma, foreign body, pulmonary embolism, heart failure, tuberculosis, aspiration, airway tumour or psychogenic/habit cough. A suppressant without diagnosis can mask deterioration.

Time course

  • Acute: usually less than 3 weeks, commonly viral upper-respiratory infection or acute bronchitis.
  • Subacute: approximately 3–8 weeks, often post-infectious but requiring review if persistent.
  • Chronic: more than 8 weeks in adults; investigate asthma/eosinophilic airway disease, upper-airway cough syndrome, reflux, smoking, ACE-inhibitor exposure, TB and structural lung disease rather than repeatedly escalating cough syrups.

2. Classification of antitussive and related cough medicines

Group Examples Main action Most appropriate role
Centrally acting opioid antitussives Codeine; hydrocodone (where available); morphine in specialist/palliative practice Increase the threshold of the medullary cough centre through opioid-receptor activity. Selected severe, distressing dry cough in adults after assessment; specialist or short-term use.
Centrally acting non-opioids Dextromethorphan; noscapine; butamirate or pholcodine where locally licensed Reduce central cough-network excitability without the full analgesic profile of conventional opioids. Short-term symptomatic treatment of dry cough; check interactions and local licensing.
Peripherally acting antitussives Benzonatate; levodropropizine; prenoxdiazine; local anaesthetic preparations Reduce activation of airway stretch or sensory receptors, or blunt local afferent transmission. Dry cough when a centrally sedating drug is undesirable, where available.
Demulcents Honey (not in infants under 1 year), glycerol, simple lozenges and warm fluids Coat and soothe irritated pharyngeal mucosa. Low-risk supportive care for uncomplicated upper-airway irritation.
Expectorants and mucolytics (not true antitussives) Guaifenesin; bromhexine; ambroxol; acetylcysteine; carbocisteine; hypertonic saline Hydrate, mobilise or reduce viscosity of secretions. Wet or tenacious sputum when airway clearance is possible; avoid pairing reflex suppression with retained secretions without a reason.
Evidence and stewardship: benefit in uncomplicated acute cough is modest and inconsistent. NICE advises that some people over 12 years may try a cough suppressant (apart from codeine) if the cough is not persistent and is not accompanied by excessive secretions; it also notes limited evidence that codeine-containing cough medicines do not help acute cough symptoms. Use the shortest effective duration and reassess a cough that does not respond.

3. Centrally acting opioid antitussives

3.1 Codeine

Codeine (3-methylmorphine) is an opioid with antitussive and analgesic activity. It is a relatively weak agonist at the mu-opioid receptor compared with morphine, but its active metabolites and central action raise the stimulus threshold of the cough centre. Approximately a variable fraction is converted by CYP2D6 to morphine; this explains major person-to-person differences. Poor metabolisers may have little effect, while ultra-rapid metabolisers can develop unexpectedly high morphine exposure and respiratory depression.

Mechanism and pharmacology

  • Mu-receptor activation reduces neurotransmitter release in cough pathways and depresses the medullary cough centre.
  • It also produces analgesia, sedation, constipation, nausea and dose-dependent respiratory depression.
  • The SlideShare reference describes oral bioavailability of about 50%, a peak around 1 hour and a plasma half-life of roughly 3–4 hours; clinical effect and toxicity may last longer in renal or hepatic impairment.
  • In the reference deck, 15 mg was reported to reduce coughing by about 40% and 60 mg by about 60% compared with placebo; these historic comparisons do not justify escalating a non-responsive cough without reassessment.

Indications

  • Short-term relief of a severe, distressing, dry cough in a carefully assessed adult when non-opioid options are ineffective or unsuitable.
  • Selected palliative-care cough under a documented plan; treat the underlying cause whenever possible.
  • It is not a routine medicine for uncomplicated viral cough, asthma with bronchospasm, a wet cough with retained sputum or suspected lower-airway infection without assessment.

Adult dosing

Product or approach Typical adult regimen Limits and notes
Immediate-release antitussive 10–20 mg orally every 4–6 hours as required. Do not exceed 120 mg in 24 hours for a cough regimen unless a local specialist formulary explicitly directs otherwise.
Codeine linctus 15 mg/5 mL 5–10 mL (15–30 mg) three or four times daily. Measure with an oral syringe or supplied measure. Product labels and national controlled-drug rules take precedence.
Elderly, frail, renal or hepatic impairment Start below the usual adult dose and extend the interval. Review sedation, respiratory rate, bowel function and accumulation before repeating.

Contraindications and major cautions

  • Significant respiratory depression, acute severe asthma without monitoring, severe hypoxia, paralytic ileus or known hypersensitivity.
  • Children under 12 years: do not use opioid cough medicines; many regulators also restrict use in adolescents with breathing problems or after tonsil/adenoid surgery.
  • Breastfeeding: avoid because morphine exposure in breast milk can cause life-threatening neonatal sedation or respiratory depression.
  • Use great caution in COPD, obstructive sleep apnoea, head injury or raised intracranial pressure, impaired consciousness, severe liver or kidney disease, hypotension, urinary retention, prostatic enlargement and a history of substance-use disorder.
  • Pregnancy requires an individual risk–benefit decision; prolonged use near delivery may cause neonatal respiratory depression or withdrawal.

Adverse effects

  • Common: drowsiness, dizziness, nausea, vomiting, constipation, dry mouth, pruritus, sweating and urinary retention.
  • Respiratory: slow or shallow breathing, hypoxia, carbon-dioxide retention, bronchospasm in susceptible patients and sleep-related apnoea.
  • Cardiovascular/neurological: hypotension, confusion, delirium, impaired coordination and, rarely, bradycardia.
  • Longer use: tolerance, physical dependence, withdrawal, misuse and opioid-use disorder.

Interactions

  • Alcohol, benzodiazepines, sedative antihistamines, gabapentinoids, hypnotics, antipsychotics and other opioids can produce additive sedation, respiratory depression, coma and death.
  • CYP2D6 inhibitors (for example fluoxetine, paroxetine, bupropion and quinidine) may reduce conversion to morphine and apparent effect; CYP2D6 ultra-rapid metabolism increases toxicity risk.
  • Cimetidine and other enzyme inhibitors can alter opioid exposure. Do not add another paracetamol-containing combination without calculating the total paracetamol dose.
  • Anticholinergic drugs increase constipation, urinary retention and confusion.

Monitoring and overdose response

Before and after dosing, document the cause and character of cough, respiratory rate, oxygen saturation, level of consciousness, pain or distress, bowel function and concurrent sedatives. If overdose is suspected, stop the opioid, call for emergency help, open and support the airway, give oxygen, assist ventilation when required, monitor glucose and obtain IV/IO access. Naloxone is the specific antagonist; because its duration can be shorter than the opioid effect, repeated doses or an infusion and prolonged observation may be needed. Do not assume a normal initial response guarantees safety.

3.2 Hydrocodone

Hydrocodone is a stronger opioid antitussive used in some countries, usually in combination with homatropine or guaifenesin. It is not a routine first-line cough medicine in Uganda and must only be used if locally authorised and prescribed. Its risks—respiratory depression, misuse, constipation and dependence—are greater than those of many non-opioid alternatives.

  • Mechanism: mu-opioid receptor agonism raises the cough threshold and depresses central respiratory drive.
  • Adult labelled example: hydrocodone bitartrate/homatropine oral solution 5 mL every 4–6 hours as required, maximum 30 mL in 24 hours; exact strength varies, so dose in milligrams must be checked on the product.
  • Do not use: under 18 years for the cited adult product, acute febrile productive cough, chronic respiratory disease where secretion retention would harm, significant respiratory depression or with alcohol/benzodiazepines and other CNS depressants.
  • Reassess non-response: never keep increasing the dose of an unresponsive cough; search for pneumonia, asthma, foreign body, pulmonary oedema, TB, malignancy or another cause.

4. Centrally acting non-opioid antitussives

4.1 Dextromethorphan

Dextromethorphan is the dextrorotatory morphinan analogue of levorphanol. At therapeutic antitussive doses it has little clinically useful analgesic or opioid respiratory-depressant effect, although overdose can cause profound CNS and respiratory toxicity.

Mechanism

  • Suppresses cough through central action involving the medullary cough network.
  • Acts as an NMDA-receptor antagonist and sigma-1-receptor agonist; it also inhibits serotonin and norepinephrine reuptake to a clinically important degree in interactions and overdose.
  • It is metabolised predominantly by CYP2D6, so fluoxetine, paroxetine, bupropion, quinidine and other inhibitors can raise concentrations.

Indications

  • Short-term relief of a troublesome, dry, non-persistent cough in adults and appropriately aged children according to the exact product label.
  • Not a treatment for asthma, COPD exacerbation, pneumonia, TB, a cough with copious sputum or a cough that is masking a dangerous process.

Dosing

Formulation or age Common regimen Important limit
Adults and adolescents ≥12 years 10–20 mg every 4 hours, or 30 mg every 6–8 hours. Maximum 120 mg in 24 hours from all products combined.
Example 15 mg/5 mL liquid label 10 mL (30 mg) every 6–8 hours; no more than four doses in 24 hours. Concentration varies; read the bottle rather than converting by memory.
Children 6–11 years For the cited 15 mg/5 mL product: 5 mL (15 mg) every 6–8 hours, maximum four doses in 24 hours. Use only a product specifically labelled for the child’s age and weight; do not extrapolate adult capsules.
Children <6 years Do not use the cited adult liquid; many jurisdictions discourage routine OTC cough-and-cold medicines in young children. Seek an assessment and treat the cause.

Adverse effects and precautions

  • Dizziness, drowsiness, headache, nausea, vomiting, abdominal discomfort and rash/urticaria; the reference deck describes these as the usual clinical effects.
  • High doses can cause euphoria, agitation, hallucinations, dissociation, ataxia, tachycardia, hypertension, seizures, coma and respiratory depression. Misuse of concentrated syrup or multiple combination products is a particular hazard.
  • Do not use with an MAOI or within 14 days of stopping one. Use caution with SSRIs, SNRIs, TCAs, tramadol, linezolid, lithium, MDMA and other serotonergic medicines because of serotonin syndrome.
  • Assess for duplicate dextromethorphan in multiple “cold and flu” products; combination products may also duplicate paracetamol, antihistamines or decongestants.

Serotonin syndrome: recognition

Suspect serotonin toxicity when a patient taking dextromethorphan develops agitation or confusion, diaphoresis, fever, diarrhoea, tremor, hyperreflexia, clonus, myoclonus, hypertension or tachycardia. Stop serotonergic medicines, provide ABC support, control agitation and hyperthermia, obtain urgent senior/toxicology advice and treat severe cases in a monitored setting.

4.2 Noscapine and other local-formulary non-opioids

Noscapine is a non-analgesic benzylisoquinoline derivative used in some formularies as a central cough suppressant. It does not provide the typical analgesic effect of codeine and is not classified as a conventional opioid analgesic, but sedation, dizziness and gastrointestinal effects can occur. Adult schedules commonly use 15–30 mg up to three or four times daily, depending on the formulation; because strengths and paediatric licensing vary widely, use the local product information rather than copying a dose between syrups.

Butamirate, pholcodine, cloperastine, levodropropizine and prenoxdiazine appear in some national formularies but availability and licensing are not uniform. Teach them by mechanism and local formulary status; never invent a paediatric dose from an adult product. If one is used, document the exact strength, age/weight, maximum daily dose and duration.

5. Peripherally acting antitussives

5.1 Benzonatate

Benzonatate is chemically related to local anaesthetics. It anaesthetises stretch receptors in the respiratory passages, lungs and pleura, thereby reducing afferent cough signalling without the central respiratory depression of an opioid at recommended doses.

  • Indication: symptomatic relief of cough in adults and children over 10 years where the product is licensed.
  • Dose: 100–200 mg orally three times daily as needed; maximum single dose 200 mg and maximum total 600 mg/day in three divided doses.
  • Administration: swallow capsules whole. Do not chew, suck, dissolve or crush them; numbness of the mouth or throat can cause choking, laryngospasm or aspiration.
  • Adverse effects: oral numbness if mishandled, nausea, constipation, dizziness, sedation, confusion, bronchospasm and hypersensitivity.
  • Overdose: may produce restlessness, tremor, seizures, coma, cardiac dysrhythmia and rapid death. Accidental ingestion by a child is an emergency; call poison-control/toxicology services and provide ABC support.

5.2 Levodropropizine and prenoxdiazine

  • Levodropropizine: a peripheral sensory-neuron suppressant, used in some countries for dry cough. A common adult regimen is 60 mg three times daily, separated by at least 6 hours; local product restrictions and renal/hepatic cautions apply. Drowsiness and gastrointestinal upset may occur.
  • Prenoxdiazine: reduces peripheral sensory-receptor excitability. Common teaching references describe 100–200 mg three times daily, but it is not universally available. Tablets should be swallowed whole, and the local formulary must determine the approved dose.
  • Neither is a substitute for bronchodilator therapy in asthma, antibiotics when bacterial infection is diagnosed, or airway clearance in bronchiectasis or neuromuscular weakness.

5.3 Local anaesthetic and demulcent measures

Warm fluids, simple lozenges, glycerol preparations and honey (only in children older than 1 year) can soothe pharyngeal irritation. Topical lidocaine or other local anaesthetics are specialist interventions for selected airway procedures, not routine self-treatment; excessive topical anaesthesia can impair protective swallowing and increase aspiration risk.

6. Related medicines often confused with antitussives

6.1 Guaifenesin: an expectorant, not a cough suppressant

The reference SlideShare deck describes guaifenesin as an orally administered expectorant that increases the volume and decreases the viscosity of respiratory secretions, making them easier to expel. It is readily absorbed, has an approximate 1-hour half-life and is metabolised to a urinary metabolite. It may temporarily relieve cough due to minor throat or bronchial irritation, but evidence for uncomplicated acute cough is limited and many authorities do not recommend routine use.

Form Typical adult/≥12-year dose Instructions
Immediate-release 200–400 mg every 4 hours; maximum 2,400 mg/day. Take with adequate fluid unless fluid restriction is clinically required.
Extended-release 600 mg 600–1,200 mg every 12 hours; maximum 2,400 mg/day. Swallow whole; do not crush or chew.
Extended-release 1,200 mg 1,200 mg every 12 hours; maximum 2,400 mg/day. Confirm the strength and avoid combining with another guaifenesin product.
Children Use only an age-labelled product; many extended-release products are not for children under 12 years. Measure liquid with an oral syringe; do not use adult formulations for young children.

Adverse effects are usually mild (nausea, vomiting, abdominal discomfort, dizziness or rash). A productive cough should be assessed before combining guaifenesin with codeine or dextromethorphan: increasing sputum while suppressing its expulsion may worsen retention.

6.2 Mucolytics and airway-clearance drugs

Acetylcysteine, bromhexine, ambroxol, carbocisteine, dornase alfa and hypertonic saline are covered in the separate Mucolytics lesson. They are selected when secretions are thick or tenacious and the patient can mobilise and expectorate them. The reference deck notes that inhaled acetylcysteine can act rapidly—within about 1 minute, with maximal effect in 5–10 minutes—while direct airway instillation acts immediately in trained settings. Never use this information to delay suction, bronchoscopy or definitive airway management.

6.3 Antihistamines and decongestants

First-generation antihistamines may reduce rhinorrhoea and post-nasal drip but cause sedation, dry mouth, urinary retention and impaired coordination. Decongestants may raise blood pressure or heart rate. They are not general-purpose cough suppressants, and combination “cold remedies” increase the risk of duplicate ingredients and dosing errors.

7. When not to suppress cough

  • Copious secretions: bronchiectasis, cystic fibrosis, pneumonia, COPD exacerbation, pulmonary oedema or a tracheostomy requiring clearance.
  • Bronchospasm: asthma or anaphylaxis requires bronchodilation, oxygen and other emergency treatment—not simply a cough suppressant.
  • Airway obstruction: choking, foreign body, stridor or a silent chest requires airway assessment and escalation.
  • Haemoptysis: assess severity and cause; do not mask a potentially life-threatening bleed.
  • Suspected TB, pneumonia, pulmonary embolism or malignancy: investigate and treat the cause.
  • Impaired consciousness or weak cough: sedation increases aspiration and retention risk.
  • Children with unexplained or persistent cough: identify the diagnosis; routine cough medicines have little evidence and can cause serious harm.
  • Acute uncomplicated cough: explain that cough often settles in 3–4 weeks; supportive care and safety-netting are frequently more useful than escalating medicines.

8. Practical emergency approach to a coughing patient

ABCDE sequence

  1. Airway: look for obstruction, stridor, pooled secretions, inability to speak or silent chest. Suction visible secretions and prepare advanced airway support if deteriorating.
  2. Breathing: respiratory rate, work of breathing, oxygen saturation, chest expansion, wheeze, crackles and cyanosis. Give oxygen to the appropriate target and treat bronchospasm, pulmonary oedema or infection as indicated.
  3. Circulation: pulse, blood pressure, perfusion, temperature and ECG when opioid toxicity, sepsis, pulmonary embolism or dysrhythmia is possible.
  4. Disability: mental status, glucose, sedation score and signs of opioid or dextromethorphan toxicity.
  5. Exposure and history: onset, dry/wet character, sputum or blood, fever, choking episode, TB exposure, smoking, ACE-inhibitor use, pregnancy, allergies, all combination medicines and drug or alcohol use.

Choosing symptomatic treatment after assessment

Presentation Preferred direction Avoid or use cautiously
Dry cough, no red flags, adult, short duration Fluids, warm demulcent measures; consider a short course of dextromethorphan if appropriate. Routine opioids; duplicated combination products; prolonged use.
Severe dry cough preventing sleep after diagnosis is clear Short, documented course of non-opioid or carefully titrated opioid in an adult, with a stop date. Alcohol, benzodiazepines, driving, dose escalation and breastfeeding exposure.
Wet cough with sputum Hydration if safe, physiotherapy, bronchodilator or mucolytic when indicated, and treatment of the cause. Suppressing cough while secretions are retained.
Wheeze, hypoxia or increased work of breathing ABCDE, oxygen, inhaled bronchodilator, corticosteroid or other disease-specific treatment. Using antitussive as the primary emergency treatment.
Opioid-induced respiratory depression Airway support, assisted ventilation, oxygen, naloxone and monitoring. Oral fluids or waiting for the patient to “sleep it off.”
Dextromethorphan plus serotonergic drug Stop offending medicines, manage serotonin syndrome and obtain toxicology advice. Further cough syrup or another serotonergic medicine.

9. Contraindications, interactions and monitoring checklist

Before prescribing or dispensing

  • Confirm the diagnosis and whether the cough is dry or productive.
  • Check age, weight, pregnancy/breastfeeding, renal/hepatic function and respiratory reserve.
  • Ask specifically about alcohol, opioids, benzodiazepines, sedative antihistamines, antidepressants, tramadol, linezolid, MAOIs and recreational use of cough syrups.
  • Read every active ingredient in combination products; calculate the total daily dose.
  • Choose a measured formulation, explain the duration and write a stop/review date.

During treatment

  • Reassess cough frequency, sleep, sputum clearance, oxygen saturation, respiratory rate, sedation and functional status.
  • Stop and investigate if cough becomes productive, fever or dyspnoea develops, haemoptysis occurs, or there is no meaningful improvement.
  • Advise patients not to drive or operate machinery if drowsy or dizzy.
  • Keep opioid, dextromethorphan and benzonatate products locked away; accidental ingestion by children can be fatal.

Withdrawal and dependence

Repeated opioid use can cause tolerance, withdrawal and dependence. If codeine has been used regularly, do not abruptly stop a high or prolonged dose without a plan; tapering, addiction assessment and treatment of the underlying cough may be required. Dextromethorphan misuse can also produce psychological dependence and neuropsychiatric toxicity.

10. Clinical cases for emergency-medicine students

Case 1: uncomplicated dry cough

A 24-year-old has a 4-day dry cough after a cold, normal oxygen saturation, no fever, no chest pain and a clear chest. Explain that cough commonly resolves within several weeks. Offer fluids, honey if age-appropriate and a short, age-labelled non-opioid product only if the symptom is genuinely distressing. Provide safety-net advice for breathlessness, haemoptysis, high fever or worsening symptoms.

Teaching point: a medicine is optional; an examination and safety-net are essential.

Case 2: wet COPD exacerbation

A 67-year-old with COPD has increased purulent sputum, wheeze and respiratory distress. A family member requests codeine syrup. Do not suppress the cough. Perform ABCDE, give appropriate oxygen, inhaled bronchodilators and corticosteroid, assess for infection and ventilatory failure, and support airway clearance.

Teaching point: opioid cough suppression may worsen secretion retention and carbon-dioxide narcosis.

Case 3: codeine-related respiratory depression

An adult becomes difficult to rouse after codeine linctus and alcohol. Respiratory rate is 6/min with shallow breathing and pinpoint pupils. Call for help, open the airway, assist ventilation, give oxygen, obtain access and administer titrated naloxone. Reassess repeatedly because naloxone may wear off before the opioid.

Teaching point: airway and ventilation are the priority; do not wait for laboratory confirmation.

Case 4: dextromethorphan and antidepressant interaction

A patient taking fluoxetine uses a high-dose dextromethorphan-containing cold preparation and develops agitation, sweating, tremor, diarrhoea, hyperreflexia and fever. Stop serotonergic agents, assess ABCs, control agitation and hyperthermia, and arrange urgent monitored care and toxicology advice.

Teaching point: a cough medicine can precipitate serotonin toxicity, especially when several products are combined.

Case 5: benzonatate ingestion

A child is found chewing an adult’s benzonatate capsule and soon becomes dizzy and unwell. Treat as a poisoning emergency: remove remaining material, protect the airway, monitor ECG and neurological status, and contact poison-control/toxicology services. Never tell families to let children suck or chew benzonatate capsules.

Teaching point: the dosage form and administration instructions are part of the pharmacology.

11. High-yield revision summary

  • Cough protects the airway; suppress only after identifying whether it is dry or productive and excluding red flags.
  • Codeine is a mu-opioid antitussive; adult antitussive dosing is commonly 10–20 mg every 4–6 hours, maximum 120 mg/day, but local product instructions control.
  • Codeine toxicity is more likely with alcohol, benzodiazepines, other sedatives, respiratory disease, CYP2D6 ultra-rapid metabolism and breastfeeding exposure; naloxone treats respiratory depression.
  • Hydrocodone is a potent opioid reserved for selected adults where locally authorised; never increase the dose of an unexplained or unresponsive cough.
  • Dextromethorphan is a non-opioid central suppressant; common adult maximum is 120 mg/day. Avoid MAOIs and watch for serotonin syndrome with SSRIs, SNRIs, TCAs, tramadol and linezolid.
  • Benzonatate acts peripherally; swallow whole. Maximum single dose 200 mg and total daily dose 600 mg; accidental paediatric ingestion can be rapidly fatal.
  • Guaifenesin is an expectorant, not an antitussive. Immediate-release adult dosing is commonly 200–400 mg every 4 hours; extended-release 600–1,200 mg every 12 hours; maximum 2,400 mg/day.
  • Mucolytics improve secretion handling; they do not justify suppressing an effective productive cough or delaying suction/bronchoscopy.
  • In children, pregnancy, breastfeeding, older age, renal/hepatic impairment and polypharmacy, use the local formulary and product label and seek senior advice.

Sources for further study

Educational disclaimer: This lesson supports supervised clinical learning. Doses, age restrictions, controlled-drug rules and product concentrations vary by country and formulation. Verify the current Ugandan/National Drug Authority formulary, hospital protocol and manufacturer information before prescribing.

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