Two or more courses of antibiotics in a year reduces the chances of further doses working in children, a new study suggests.

A study involving teams from Oxford, Cardiff and Southampton universities examined the dangers of overprescribing antibiotics in kids – particularly for common conditions like coughs, sore throats and earache.

Researchers analysed the records of more than 250,000 preschool children and found that those who were given more than two courses in a year were 30% more likely to find the next course less effective. This was likely to lead to them needing further treatment, including being admitted to hospital.

“When children receive more antibiotics, their likelihood of re-consulting a health professional is affected and inadvertently increases clinical workload,” said Dr Oliver van Hecke from the University of Oxford.

[Read More: Here’s What You Should And Shouldn’t Be Taking Antibiotics For]

A study last year suggested that one in five antibiotics prescribed was unnecessary. However, in the past, antibiotics were used for conditions like chest infections, ear infections and sore throats – so parents sometimes demand them from their doctors. 

Royal College of GPs chairwoman, Professor Helen Stokes-Lampard, urged parents to listen to their GPs if they say antibiotics are not needed: “GPs are acutely aware of the potential dangers of prescribing antibiotics when they are not absolutely necessary – and how this can contribute to growing resistance to these important drugs, which is a global concern.

“There is a very difficult balance to be struck as antibiotics can be lifesaving drugs for severe infection-related conditions such as sepsis – but instances where children who have an infection really do need antibiotics should be relatively uncommon.” 

Professor Stokes-Lampard added that GPs are “highly trained prescribers” and will not suggest any course of medication unnecessarily. 

Antibiotic resistance is classed by the World Health Organisation as one of the 10 biggest threats to global health. A study published last week highlighted the increased resistance to two of the most widely-used antibiotics among conditions like E.coli and Klesiella.

Potential ways to reduce antibiotic resistance include improved screenings for resistant bacteria, reduced use on livestock, experimental use of viruses to eradicate certain bacteria and more widespread awareness of the dangers of unnecessary antibiotic use.