Two thirds of people have serious misconceptions about asthma, warn experts.
Asthma is not just a childhood worry
A National Asthma Campaign survey found many people wrongly think the condition is only associated with childhood.
In fact, 40% of asthmatics only start to suffer as adults and two out of every three develop the condition after the age of 15.
Asthma, which continues to be one of the most common long-term conditions in the UK, can develop at any age.
Sandra Phillips, 53, of Norfolk, was among those who had no idea she could develop asthma later in life.
"I had been feeling out of breath and wheezing a lot more than in my forties.
Now I'm on the correct medication, my life is back to normal and I am no longer restricted in what I can do
"I put this down to the fact I was getting older until my daughter suggested perhaps I had developed asthma.
"I always thought you developed asthma as a child.
"Now I'm on the correct medication, my life is back to normal."
Professor Martyn Patridge, chief medical adviser to the National Asthma Campaign, said: "Many people have asthma but don't realise it.
"It is vital to recognise the symptoms early on in order to receive appropriate treatment and control the condition by working with your GP, practice nurse or local pharmacist.
"If the condition goes untreated, it can lead to a downward spiral of poor health and an increased risk of long-term lung damage."
An information leaflet about asthma will be available in Boots' stores throughout April