Treatment for refractory or unexplained chronic cough
Gefapixent for Chronic Cough: How It Works, Benefits and UK Access
Gefapixent, sold under the brand name Lyfnua, is a licensed medicine for adults whose chronic cough remains unexplained or continues despite appropriate treatment of underlying causes. It targets the over-sensitive sensory nerves involved in cough hypersensitivity.
- Cough hypersensitivity
- P2X3 receptors
- Gefapixent
- Taste disturbance
- Behavioural therapy
- UK access
It is not a first-line cough medicine
Gefapixent is considered only after warning signs, common causes and treatable conditions have been assessed and appropriate non-drug treatment has been offered.
Taste disturbance is common
Food and drink may taste different, weaker or absent. This is the most important adverse effect to consider when balancing likely benefit against treatment burden.
What is gefapixent?
Gefapixent is an oral P2X3-receptor antagonist licensed for adults with refractory or unexplained chronic cough. It works by reducing abnormal sensory-nerve signalling involved in the urge to cough.
A chronic cough is generally defined as a cough lasting longer than eight weeks. In some people, the cough continues even after common causes have been investigated and appropriately treated. In others, no clear underlying cause is found despite a structured clinical assessment.
These patterns are described as:
Refractory chronic cough
A chronic cough that persists despite appropriate assessment and treatment of the condition or conditions thought to be causing it.
Unexplained chronic cough
A chronic cough for which no cause has been identified despite an appropriately comprehensive assessment.
P2X3-receptor antagonist
Gefapixent blocks a receptor on sensory nerves involved in detecting ATP and initiating abnormal cough signalling.
45 mg twice daily
Tablets are swallowed whole and can be taken with or without food. Dose frequency may be reduced in severe renal impairment.
Gefapixent is not intended for a short-lived viral cough, an acute chest infection or a cough caused by an untreated condition. It does not replace diagnosis and treatment of asthma, reflux, rhinosinusitis, bronchiectasis, infection, medication-related cough or another identified cause.
Learn more about specialist chronic cough assessment in London .
Chronic cough hypersensitivity: when the cough reflex becomes over-sensitive
Cough is normally a protective reflex. It helps remove inhaled material, mucus and irritants from the respiratory tract. In cough hypersensitivity, the sensory system responsible for triggering cough becomes unusually responsive.
Everyday exposures that would not normally provoke troublesome coughing can then trigger an urge to cough or a prolonged coughing episode.
People commonly describe a persistent tickle, irritation or urge to cough that is difficult to suppress. The cough can disturb sleep, work, relationships, social activity and continence. Severe episodes may cause chest pain, dizziness, vomiting or exhaustion.
Cough hypersensitivity describes an abnormal cough mechanism. It does not remove the need to investigate whether asthma, reflux, airway disease, infection, medication or another condition is contributing.
How gefapixent fits the biology of cough hypersensitivity
Airway irritation
Inflammation or epithelial injury can increase the release of extracellular ATP.
P2X3 activation
ATP binds to P2X3-containing receptors on vagal sensory nerve fibres.
Cough signalling
Sensory nerves send an exaggerated urge-to-cough signal towards the brain.
Receptor blockade
Gefapixent blocks P2X3 signalling and can reduce abnormal cough activation.
P2X3 receptors also contribute to taste signalling. This helps explain why blocking them can reduce cough in some patients while also causing taste disturbance.
Gefapixent reduces signalling rather than treating every cause
Gefapixent acts on the cough-reflex pathway. It does not treat an active infection, remove retained mucus, suppress uncontrolled asthma or correct aspiration. Any underlying or associated respiratory condition still needs appropriate management.
Where gefapixent fits in the chronic cough pathway
Doctors should not jump directly from a persistent cough to a specialist neuromodulatory medicine. A structured pathway is needed first.
- Confirm that the cough is chronic Establish how long it has been present, how it started, the triggers and its effect on sleep, work and daily life.
- Check for warning signs Haemoptysis, weight loss, severe breathlessness, recurrent pneumonia, abnormal examination findings or another concerning feature may require urgent investigation.
- Review medicines and exposures Smoking, vaping, workplace exposure and ACE-inhibitor medication can contribute to cough.
- Perform appropriate investigations Assessment may include chest imaging, spirometry, airway inflammation tests, blood tests, sputum testing or more specialised investigations.
- Treat identifiable causes and treatable traits Asthma, eosinophilic airway disease, reflux, upper-airway problems, bronchiectasis and infection should be addressed where present.
- Offer behavioural cough-control therapy Speech and language therapy or specialist physiotherapy can teach cough suppression, breathing control and throat-care strategies.
- Consider gefapixent if cough remains burdensome Treatment may be discussed when cough remains refractory or unexplained and continues to impair quality of life.
Behavioural cough-control therapy remains important
Specialist cough-control therapy has a favourable safety profile and can improve cough frequency, severity and quality of life. It may be used before medication or alongside medication as part of a comprehensive programme.
What the pivotal gefapixent trials found
The two pivotal phase 3 studies, COUGH-1 and COUGH-2, enrolled adults with refractory or unexplained chronic cough and compared gefapixent with placebo.
| Question | What the studies found | What it means in practice |
|---|---|---|
| Did 45 mg twice daily reduce cough frequency? | The licensed dose reduced objective 24-hour cough frequency relative to placebo. | Some patients cough less often, but the average additional benefit over placebo is modest. |
| Did the lower dose work? | The 15 mg twice-daily dose did not meet the principal efficacy objective. | It is not the licensed therapeutic dose. |
| Was response consistent for everyone? | Individual responses varied considerably. | Treatment should have agreed goals and a planned review. |
| What was the main tolerability problem? | Taste disturbance was common and led some participants to stop treatment. | The likelihood and effect of taste alteration should be discussed before prescribing. |
The European regulator concluded that gefapixent has a modest effect on daily cough frequency and that its benefits outweigh its risks for the licensed patient group.
The United States regulator reached a different conclusion. The FDA concluded that the submitted application did not provide substantial evidence of effectiveness and did not approve the medicine. This difference explains why availability and media coverage vary between countries.
Gefapixent is not expected to eliminate cough in every patient. The aim is a meaningful improvement in outcomes such as coughing fits, sleep, continence, work, social confidence or overall quality of life.
When gefapixent may be considered
Gefapixent may be considered when all of the following broad principles apply:
Examples of useful treatment goals
Goals may include fewer severe coughing attacks, less waking at night, improved ability to speak, reduced stress incontinence, better participation in meetings or social activity, and a meaningful improvement in a validated cough questionnaire.
When gefapixent should not be used or should be reconsidered
Gefapixent is not appropriate for every persistent cough
- It should not be used to bypass investigation of a new or unexplained cough.
- It is not intended for acute cough or an untreated respiratory infection.
- It should not replace treatment of uncontrolled asthma, active reflux-related disease or another identifiable cause.
- It must not be used in a patient with known hypersensitivity to gefapixent or an excipient.
- It is not indicated for people younger than 18 years.
- Pregnancy and breastfeeding require individual specialist assessment because human data are limited.
- Severe renal impairment requires a modified dosing frequency according to the product information.
- Treatment should be stopped or reconsidered when there is no meaningful benefit or adverse effects are unacceptable.
Dose and how gefapixent is taken
45 mg twice daily
Doses are normally taken at approximately regular intervals, following the prescriber’s instructions.
Swallow tablets whole
Tablets should not be crushed, split or chewed and may be taken with or without food.
Dose frequency may change
Severe renal impairment in a patient not receiving dialysis may require less frequent dosing.
Follow the patient leaflet
Do not take a double dose to compensate for a forgotten tablet.
The prescriber should review kidney function, current medication, relevant allergies, pregnancy or breastfeeding considerations and the current product information before treatment.
Side effects and what should be monitored
Taste disturbance
Food or drink may taste different, metallic, bitter, salty, weaker or absent. This includes dysgeusia, hypogeusia and ageusia. It is the most characteristic and common adverse effect.
Gastrointestinal symptoms
Nausea, diarrhoea, indigestion or a dry mouth may occur. These are often mild to moderate but should be reviewed if persistent.
Neurological symptoms
Dizziness or headache may occur. Patients who feel dizzy should not drive or use machinery until the symptom has resolved.
Most taste-related reactions resolve after treatment stops, but recovery is not immediate in every patient. The product information reports that a small proportion of taste effects persisted for a prolonged period after discontinuation.
New or troublesome symptoms should be discussed with the prescriber. Suspected adverse drug reactions can also be reported through the MHRA Yellow Card scheme.
Taste changes can affect more than enjoyment of food
Reduced taste may alter appetite, nutrition, weight, hydration and quality of life. Patients who already have poor appetite, weight loss or nutritional vulnerability may require closer monitoring.
How to judge whether gefapixent is helping
A treatment trial should begin with measurable goals. Simply continuing because the medicine has been started is not enough.
A review at approximately 6 to 12 weeks can assess early benefit, tolerability and whether treatment should continue. Some clinical trial outcomes were formally assessed at 12 or 24 weeks, but a patient with no worthwhile improvement or significant adverse effects should not continue automatically.
Gefapixent access in the UK: private care and NHS funding
Lyfnua has a UK marketing authorisation for adults with refractory or unexplained chronic cough. This means it can legally be prescribed for its licensed indication by an appropriately qualified prescriber.
NICE’s technology appraisal was terminated because the manufacturer did not submit evidence for the appraisal. NICE is therefore unable to make a recommendation about NHS use. This is not the same as NICE concluding that the medicine should never be used.
Routine NHS commissioning is not established nationally. NHS organisations wishing to consider treatment may use their usual local or individual funding decision processes. Availability can therefore vary.
Private prescribing may be considered after specialist assessment when clinically appropriate. The patient normally pays the private consultation, prescription and pharmacy costs. Prices vary between pharmacies and can change.
A private recommendation does not oblige an NHS GP to prescribe
An NHS GP is not automatically required to convert a private prescription into an NHS prescription, particularly when the medicine is not routinely commissioned or falls outside the GP’s usual prescribing responsibility.
Conclusion
Gefapixent is a licensed option for adults with refractory or unexplained chronic cough after a structured assessment and appropriate treatment of common causes.
It blocks P2X3-receptor signalling on sensory nerves involved in cough hypersensitivity. Phase 3 trials showed a reduction in objective cough frequency at 45 mg twice daily, but the average additional benefit over placebo was modest and individual response varied.
Taste disturbance is common and is the principal trade-off. Clear treatment goals, side-effect monitoring and a planned review are therefore essential.
Behavioural cough-control therapy remains an important low-risk treatment and may be used before or alongside medication.
Gefapixent is authorised in the UK, but NICE was unable to make a recommendation because the manufacturer did not submit evidence. Routine NHS access is therefore not established, and current access is more commonly through specialist private prescribing or local funding decisions.
Frequently asked questions
Is gefapixent a cure for chronic cough hypersensitivity?
No. It reduces P2X3-mediated sensory signalling and can lower cough frequency in some patients, but it does not permanently remove the tendency to cough or cure every underlying cause.
Who is gefapixent intended for?
It is licensed for adults with refractory or unexplained chronic cough after appropriate assessment and treatment of common causes.
What is the usual dose?
The usual licensed dose is 45 mg twice daily. Severe renal impairment in a patient not receiving dialysis may require a reduced dosing frequency.
Can my NHS GP prescribe gefapixent?
Routine NHS commissioning is not established. NICE was unable to make a recommendation because the manufacturer did not submit evidence. Local or individual NHS funding decisions may sometimes be considered, but an NHS GP is not obliged to convert a private prescription.
How long does it take to work?
Timing varies. Some patients may notice an earlier change, while pivotal trial outcomes were assessed at 12 and 24 weeks. A planned clinical review at approximately 6 to 12 weeks can assess initial benefit and tolerability.
What is the most common side effect?
Taste disturbance is the most common adverse effect. Food or drink may taste different, weaker, metallic, bitter, salty or absent.
Does taste return after stopping gefapixent?
Taste disturbance resolves after discontinuation for most patients, although the timing varies and prolonged persistence has been reported in a small proportion.
How does gefapixent compare with behavioural cough therapy?
Behavioural cough-control therapy is a non-drug treatment with a favourable safety profile. It teaches cough suppression, breathing control and throat-care strategies. The treatments can be complementary rather than mutually exclusive.
Is gefapixent approved in the United States?
No. The FDA concluded that the submitted application did not demonstrate substantial evidence of effectiveness. The decision was not attributed to a new safety concern.
When should treatment be stopped?
Treatment should be reconsidered when it produces no meaningful improvement, taste disturbance or another adverse effect is unacceptable, or the clinical situation changes. Stopping should be discussed with the prescriber.
References and further information
- European Medicines Agency. Lyfnua: European public assessment report. View the EMA medicine overview
- European Medicines Agency. Lyfnua product information. View the product information
- National Institute for Health and Care Excellence. Gefapixant for treating refractory or unexplained chronic cough — terminated appraisal, TA969. View the NICE appraisal
- McGarvey L, et al. Efficacy and safety of gefapixant in refractory chronic cough and unexplained chronic cough: COUGH-1 and COUGH-2. The Lancet. 2022;399:909–923. View the COUGH-1 trial record
- US Food and Drug Administration. Pulmonary-Allergy Drugs Advisory Committee briefing materials: gefapixant. 2023. View the FDA briefing document
