The work is the first to show that even after taking race and social factors into account, heavier kids use more drugs to control their asthma and curb flare-ups than their slimmer peers.
"Improving nutritional status, preventing obesity, and stressing the importance of weight loss might improve asthma control and exacerbation risk in children and decrease the incidence of asthma in adults," researchers write in the Journal of Allergy and Clinical Immunology.
Both asthma and obesity rates have soared among kids in recent decades, reaching nearly 10 percent and 17 percent today, respectively.
While some studies have hinted at a link between the two conditions, conclusions on whether heavier kids also have more severe asthma than others have been mixed.
Dr. Kenneth B. Quinto from the University of California, San Diego, and colleagues looked back at more than 32,000 kids who'd been diagnosed with asthma and were enrolled in a Kaiser Permanente health plan. Nearly half of the children were overweight or obese.
The researchers found that the heavier kids were more likely to have more than a handful of yearly prescriptions for rescue inhalers, which contain short-acting drugs such as albuterol that open up the airways when an asthma attack is coming on.
On average, normal-weight children used 2.8 rescue inhalers a year, whereas obese kids used 3.1.