People cough in order to clear their airways. Most coughs are caused by viruses and settle down by themselves, but some people develop persistent coughing which can be anywhere from 8 weeks to several years. This is called chronic cough. People with chronic cough find the symptom distressing and it can have a major impact on their quality of life. Patients with chronic cough often report a sensation at the back of their throat which makes them feel an urge to cough. There is some evidence that Lidocaine (an anaesthetic used during medical procedures) can suppress a person's cough when given to patients via a nebuliser (a machine that turns liquid into a fine mist).

It is currently unknown whether using a local anaesthetic, such as Lidocaine, in the form of a throat spray would successfully suppress a person's cough. A throat spray would be an easier treatment option in chronic cough patients. Thus, the investigators research aims to compare cough rates, severity and urge to cough scores between Lidocaine throat spray and nebulised Lidocaine.

Inclusion Criteria:

• Male and female subjects, age 18 years and over.
• History of cough for more than 8 weeks.
• Normal chest x ray
• Chronic idiopathic cough or chronic cough resistant to treatment of specific triggers.

Exclusion Criteria:

• Smoking status:

  • Current smokers
  • Ex smokers with history of smoking > 20 pack years or those who have given up < 6 months ago.

• Prohibited medications:

  • Use of medications likely to suppress / affect cough including codeine, morphine, pregabalin, gabapentin, amitriptylline, angiotensin converting enzyme inhibitors (type 1) and baclofen.
  • Use of any anti-arrhythmic medication.
  • Use of cimetidine, beta blockers, or diuretics.

• Cardiovascular conditions:

  • Sinoatrial disease, bradycardia or all types of heart blocks.
  • History of ischaemic heart disease or heart failure.
  • Clinically significant abnormal electrocardiogram (ECG) at Screening or Baseline.
  • History of cardiac surgery

• Respiratory conditions:

  o Asthma.

• Central nervous system / Peripheral nervous system conditions:

  • Epilepsy.
  • Myasthenia gravis.

• Miscellaneous:

  • History of hepatic or renal dysfunction.
  • Porphyria
  • History of hypersensitivity to Lidocaine or related drugs.
  • Pregnancy or breast feeding.
  • Participation in another trial within the preceding 6 weeks.
  • Trauma or ulceration to oral mucosa.
  • History of chest or upper airway infection within the past 6 weeks.
  • Conditions which may affect cough response such as stroke, diabetes, Parkinson's Disease.