Asthma sufferers may be at risk of pneumonia if they use an inhaler.
Their risk of being hospitalised with the potentially fatal complication is 83 per cent higher than non-inhaler users'.
Breathing in the steroids found in inhalers is thought to be to blame.
Around 5.4 million people in the UK are being treated for asthma.
Steroid-containing inhalers are commonly prescribed to control inflammation in the airways.
Asthma patients using inhalers are 83% more more likely to be hospitalised with pneumonia
Scientists from McGill University, Montreal analysed 152,412 asthma patients.
The hospitalisation risk varied according to the steroid used and its dose.
Yet, even low steroid doses were associated with a significantly increased risk.
Asthma is a lung condition that can cause breathing difficulties.
It occurs when the breathing tubes to the lungs become inflamed and narrow.
Symptoms include wheezing, breathlessness, coughing and a tight feeling in the chest.
It may be triggered by exercise, cold air or cigarette smoke.
There is no cure.
Inhalers relieve symptoms and reduce inflammation.
Source: NHS Choices
It is unclear why inhaling steroids, also known as corticosteroids, is linked to pneumonia in asthma patients.
A pneumonia risk is established among patients using inhalers for the lung condition chronic obstructive pulmonary disease (COPD).
Study author Dr Pierre Ernst, said: 'While the increase in risk of pneumonia with the use of inhaled corticosteroids is well recognized in COPD, in asthma patients the evidence has been equivocal.
'Our study suggests the risk may be present in asthma, although pneumonia in patients with asthma remains unusual and inhaled corticosteroids remain the best therapy available.'
This comes after researchers from the University of Newcastle in New South Wales, Australia, found that taking fibre supplements may ease asthma symptoms.
The supplements altered the gut's microbiome and had a positive impact on airway inflammation.