Officials at Public Health England (PHE) reminded GPs that many patients do not benefit from antibiotics even if they are producing green phlegm.
Around 40% of patients incorrectly believe antibiotics can successfully treat these symptoms, leading to frequent requests for prescriptions.
Health chiefs acknowledged the pressure on GPs to prescribe, but warned that it adds to the cycle of antibiotic resistance.
PHE and the RCGP have issued guidance to help GPs explain to patients when antibiotics are not needed.
GPs should tell patients that antibiotics will have no effect in otherwise healthy people, including asthmatics, regardless of phlegm colour.
But antibiotics may be necessary if patients produce green phlegm and also have COPD, recurrent chest infection, or signs of other serious illness.
Antibiotics may also be appropriate in older patients who have been hospitalised in the past year, have diabetes or heart failure, or are taking oral glucocorticoids.
GPs should review patients if the illness continues for three weeks or more, they said.
Dr Maureen Baker, RCGP chairwoman, said the guidance would be 'hugely helpful' for GPs and patients seeking alternatives to antibiotics.
Dr Cliodna McNulty, head of PHE’s primary care unit, insisted patients would be 'open' to discussing with GPs why antibiotics are not needed. 'We hope that this handy guide will help GPs in their consultations and by raising awareness we can help to reduce the demands for treatment when the body will get better by itself,' she said.
In March, England’s CMO Professor Dame Sally Davies warned that antimicrobial resistance posed a ‘catastrophic threat’ to modern medicine. The UK government has published a five-year strategy in an attempt to tackle the issue.
A study by Public Health England published in July revealed how surgeries are inundated with requests for antibiotics.