For decades, millions of asthma patients believed their biggest battle was inside their lungs. A major new European study now suggests that may only be the beginning.

Researchers studying nearly 2,700 people with severe asthma in 11 European countries have discovered that most patients are quietly fighting several other serious illnesses at the same time—including obesity, brittle bones, chronic sinus problems, and severe allergies. Many patients remain unaware of the connection between these conditions.

The findings, published in Lancet Regional Health, are being described by experts as a major wake-up call for modern asthma treatment, especially the long-term use of steroid medicines that have been relied upon for more than 50 years.

The study was led by scientists from the University of Southampton, University Hospital Southampton and the National Institute for Health and Care Research's Southampton Biomedical Research Centre, working with SHARP, a collaboration supported by the European Respiratory Society.

What shocked researchers most was the scale of the hidden burden. Nearly 91 per cent of patients with severe asthma were found to have at least one other major long-term illness, while most were living with three or more conditions together.

Doctors say the finding changes the way asthma itself should be understood.

For years, hospitals mainly treated asthma as a disease of blocked airways. But the new evidence suggests severe asthma behaves more like a chain reaction spreading across the body.

Researchers found that patients did not become ill randomly. Instead, most fell into three clear “clusters” of disease.

One cluster involved heavy steroid use. These patients often gained significant weight and developed osteoporosis—a condition where bones become thin, weak, and more likely to break. Steroids reduce inflammation and help patients breathe during dangerous asthma attacks, but long-term use has already been linked in earlier international studies to bone loss, diabetes risk and metabolic problems.

Doctors now fear the treatment itself may sometimes be adding to the health crisis.

It is a cruel double-edged sword. The medicine helps the chest but quietly harms other parts of the body.

Another cluster involved severe allergic conditions, including eczema and hay fever. A third group suffered chronic sinusitis and nasal polyps, painful growths inside the nose that can severely affect breathing and sleep.

Study lead author Prof. Ramesh Kurukulaaratchy, Professor in Respiratory Medicine and Allergy at the University of Southampton, said the findings revealed strong links between these conditions and asthma severity.

He stated that the patterns we discovered correlated with the level of asthma control, the frequency of attacks, and the required treatments.

“Better understanding these patterns will help us look beyond asthma alone and improve the care for people living with severe asthma.”

Inside respiratory clinics, doctors say many patients become so focused on breathing difficulties that other warning signs—sudden weight gain, joint pain, constant sinus blockages, or recurring skin problems— are often ignored or treated separately.

That fragmented approach may now need a radical reboot.

Joint first author Dr Anna Freeman, Respiratory Consultant at University Hospital Southampton, said the research could help millions of patients receive earlier and more targeted care.

“People with severe asthma often live with a heavy burden of other conditions, but until now, we didn’t fully understand how they were linked,” she said.

“With our results, we can improve the quality of life for millions of people across Europe who currently struggle to keep their severe asthma under control.”

Experts believe the future of asthma treatment may no longer involve simply prescribing stronger lung medicines. Instead, doctors may increasingly identify a patient’s entire disease “profile” before treatment begins.

The message emerging from the study is blunt but important: asthma may not be a lonely disease at all. Unless doctors stop chasing only the cough and start protecting the whole body, millions of patients could continue slipping into a silent cycle of worsening illness, weaker bones, and declining quality of life.