Color of Phlegm Does Not Determine Need for Antibiotics

Prescribing antibiotics for patients with discolored phlegm caused by acute cough has little or no effect on alleviating symptoms and recovery, a Cardiff University study has found.

Acute cough is one of the common reasons why people visit their general practitioner (GP) and accounts for a large proportion of antibiotics prescribed. One of the most common questions GPs ask their patients is whether they are coughing up phlegm and what color it is.

Clinicians and patients commonly believe that yellow and green phlegm production is associated with a bacterial infection, which is more likely to benefit from antibiotic treatment compared to non-productive cough or cough that produces clear phlegm.

However, in a new study published in the European Respiratory Journal, Chris Butler, MD, and his team from Cardiff University’s School of Medicine, together with colleagues from 14 European centers, present data from an observational study of 3,402 adult patients with acute cough presenting for health care in 14 primary care networks.

The research found that patients producing discolored phlegm are prescribed antibiotics more frequently than those not producing phlegm, unlike those producing clear/white phlegm.

Crucially, antibiotic treatment was not associated with greater rate or magnitude of symptoms score resolution among those who produced yellow or green phlegm. Neither was recovery among those feeling generally unwell on its own, or taken together with phlegm production, associated with antibiotic treatment.

Clinicians and patients are therefore likely to both be over interpreting the importance of the color of phlegm in the decision whether or not to prescribe, or take, antibiotics.

“One of the exciting things about this research is that our findings from this large, multi-country observational study resonate with findings from randomized trials where benefit from antibiotic treatment in those producing discolored phlegm has been found to be marginal at best or non-existent,” Butler said in a statement.

“Our findings add weight to the message that acute cough in otherwise well adults is a self-limiting condition and antibiotic treatment does not speed recovery to any meaningful extent,” he added.

“In fact, antibiotic prescribing in this situation simply unnecessarily exposes people to side effects from antibiotics, undermines future self care, and drives up antibiotic resistance.”

A single-center study, using different research methods, by one of Butler’s predecessors at Cardiff University, drew conclusions similar to this new research. Despite this, non-evidence based practice remains common across the United Kingdom.