More than half of children diagnosed with asthma do not have the condition and are receiving unnecessary treatment, according to new research.
Despite 1.1 million children having treatment for the condition in the UK, a study from a Dutch university claims GPs do not always perform the tests which can confirm a child has asthma, leading to over-diagnosis.
New guidelines are now being developed to help GPs in the UK diagnose children correctly, according to The Daily Telegraph.
Asthma should be confirmed using lung function testing in children under six but previous studies have suggested it is often over-diagnosed.
Research from University Medical Centre Utrecht looked at the medical records of 652 youngsters in the Netherlands diagnosed with asthma and found that in 53.5% of children, "the signs and symptoms made asthma unlikely and thus they were most likely over-diagnosed", the authors said.
They also found that only 16.1% of children diagnosed with asthma had the diagnosis confirmed with spirometry - a simple test to monitor lung function.
The number that should have undergone extra tests were 23.2%.
The authors, led by Ingrid Looijmans-van den Akker, said in their conclusion: "Over-diagnosis of childhood asthma is common in primary care, leading to unnecessary treatment, disease burden, and impact on quality of life.
"However, only in a small percentage of children is a diagnosis of asthma confirmed by lung function tests."
The results have spurred the National Institute for Health and Care Excellence (Nice) to examine how GPs diagnose asthma in the UK.
Professor Mark Baker, director of clinical practice at Nice, told the Telegraph: "Nice is developing a guideline to provide advice for primary, secondary and community care healthcare professionals on the most suitable tests for accurately diagnosing asthma and how to help people monitor and control their symptoms.
"As part of this work, Nice is inviting GP practices to take part in a project to check the feasibility of some diagnostic tests that Nice proposes to recommend."
The chairwoman of the Royal College of GPs has called for more investment in diagnostic equipment to help doctors who are "highly trained" to identify symptoms.
Dr Maureen Baker said: "Some useful diagnostic tests are already available in primary care in the UK, but we need increased investment so that we can broaden GP access to this equipment and undergo the training necessary to use it in the best interests of our patients."