Cough medicines

Cough medicines

• some cough medicines (cough linctuses) are available over the counter, except for controlled drugs
• there are two types of over the counter (OTC) cough medicine:
  • cough expectorant
  • cough suppressant - decrease cough reflex to normal levels, most common OTC suppressant is dextromethorphan
  • although there is little evidence that either is effective (1)
• the logic behind use is that:
  • a 'dry cough' with little phlegm requires a cough suppressant
  • a 'productive cough' requires a cough expectorant to help bring up phlegm e.g. 'ammonia and ipecacuanha mixture BPC' - expectorants are designed to force the cough reflex to propel the phlegm out of the bronchi - there is no evidence that they have any effect.

Codeine linctus cough medicines

Codeine linctus (also known as codeine oral solution)

• authorised for the treatment of dry coughs in adults and children aged 12 to 18 years without breathing difficulties
• is not authorised for the treatment of pain
• has been used as a cough medicine (cough suppressant) for many years, although the evidence for effectiveness in short-term cough is limited
  • codeine is converted into morphine by the liver enzyme CYP2D6
    • some people (known as ultra-rapid metabolisers) convert codeine into morphine faster than others

Codeine linctus and chronic cough

• evidence indicates that morphine is effective in the treatment of chronic cough.
  • note though that patients with chronic cough may have underlying conditions, and they should undergo medical investigation to establish the best treatment.

As an opioid medicine, codeine linctus is known to be addictive.

• a review has revealed that (2)
  • codeine linctus is being used recreationally for its opioid effects, rather than for its intended use as a cough suppressant
    • carries a serious risk of addiction and overdose which can be fatal

Advice for healthcare professionals (2):

• codeine linctus is to be reclassified from a pharmacy-only medicine (P) to a prescription-only medicine (POM) owing to the risk of dependence, addiction, and overdose
• codeine linctus is only authorised for the treatment of dry cough
• codeine linctus is only considered to be effective in the treatment of chronic cough lasting over 8 weeks
• advise patients that those with a long-term cough should see a healthcare professional, for review of symptoms and may require medical assessments to check for other conditions which may be the cause of the cough
• we would encourage healthcare professionals to read the Summary of Product Characteristics for special warnings and contraindications for the use of codeine linctus, especially in patients with a history of substance abuse
• record prescription details in the patient’s summary care record (or equivalent) and encourage patients to read the Patient Information Leaflet that comes with their medicine
• report suspected adverse drug reactions to codeine linctus to the Yellow Card scheme

Reference:

• (1) Dicpinigaitis PV et al. Acute cough: a diagnostic and therapeutic challenge. Cough. 2009;5:11
• (2) Drug Safety Update volume 17, issue 7: February 2024: 1