Drugmaker GSK Plc is recalling nearly 600,000 asthma inhalers due to a defect that could prevent the device from correctly delivering medicine.

According to Reuters, the voluntary recall affects three lots of Ventolin HFA 200D inhalers. GSK has reportedly received a number of complaints indicating consumers have been finding a bulge to the outside of the wrapper of unused inhalers. According to GSK, the bulge may indicate a leak of the propellant that delivers medicine.

The recall is a Class II recall, meaning the defect GSK is not asking customers to return inhalers they already purchased. The recall instead affects inhalers currently stocked at pharmacies, retailers and wholesalers.

According to the FDA, the inhalers could cause injury or temporary illness, but the risk of serious adverse health consequences is remote.

In a statement, GSK says they don’t expect the supply of inhalers to be affected by the recall.

Alex Hider is a writer for the E.W. Scripps National Desk. Follow him on Twitter @alexhider.