Cough medicines lack evidence, says Cochrane
There is no good evidence either for or against the effectiveness of over-the-counter cough medicines, an updated Cochrane review concludes.
Researchers examined data from 25 trials involving 3,492 people (2,876 adults and 616 children) with acute cough, and compared groups of medicines with similar modes of action. They found that antitussives, antihistamines, antihistamine decongestants and antitussive/bronchodilator combinations were no more effective than placebo. Data from one trial favoured mucolytics over placebo and one trial that tested two paediatric cough syrups showed a “satisfactory response” in more of the children given the medicines than placebo (46 per cent and 56 per cent compared with 21 per cent).
The reviewers were unable to assess the efficacy of expectorant cough medicines since no trials met their inclusion criteria.
The reviewers note that the results have to be interpreted with caution since study designs, populations, interventions and outcomes varied markedly between studies. “However, most preparations appear to be safe based on those studies reporting side effects which only described a low incidence of mainly minor adverse effects,” they add (Cochrane Database of Systematic Reviews 2008; issue 1).
Other Cochrane reviews
The latest round of Cochrane systematic reviews consider evidence around the use of:
• Cranberries for urinary tract infections
• Hawthorn extract for chronic heart failure
• Alendronate for bone fractures
• Antioxidants for preventing pre-eclampsia
• Antidepressants for non-specific low back pain
Use of cranberries, hawthorn and alendronate are all supported by the reviews.
The other interventions do not fare so well. Evidence does not support routine use of antioxidants during pregnancy to reduce the risk of pre-eclampsia and other serious complications.
There is also no clear evidence that antidepressants are more effective than placebo in the management of patients with chronic low-back pain. However, the authors of the low-back pain review note that there is evidence for the use of antidepressant medicines in other forms of chronic pain.
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