More than 5.4 million Brits suffer asthma, and are now being urged to check if their inhaler is one of those affected.
The Medicines and Healthcare products Regulatory Agency (MHRA) has recalled two Ventolin and Seretide inhalers, both manufactured by Glaxo Wellcome UK Limited.
More than 4,500 blue Ventolin 200mcg inhalers and 1,400 purple Seretide 50/250mcg inhalers are affected, a spokesman told The Sun Online.
Experts warned people with asthma may find their symptoms worsen, or are not relieved by the medication during an attack.
Dr Andy Whittamore, GP and clinical lead at Asthma UK, said: “It is extremely worrying that some people with asthma may have faulty inhalers and it could put people’s lives at risk.
“The Ventolin inhalers are reliever inhalers and so are used by people while they are experiencing asthma symptoms such as a cough, breathlessness, wheezing or a tight chest.
“If someone’s inhaler is faulty they may find it doesn’t help which could be frightening and mean they’re more likely to have an asthma attack.
“We’d urge everyone with asthma to check if their inhaler is from the affected batch by checking the number on the bottom of their inhaler.
“If it is affected, they should get medical advice and return the inhaler to their pharmacist for a replacement.”
Ventolin inhalers are used to manage asthma symptoms as they occur, while Seretide inhalers are used as a preventative treatment.
The inhalers are also being recalled from hospitals, pharmacies and retailers across the UK.
Other asthma inhalers, including the more commonly used Ventolin Evohaler, are not affected.
Bernadette Sinclair Jenkins, MHRA’s regulatory assessment unit manager, said: “It is important people check whether they have an affected inhaler.
“We want patients and their families to be confident treatment will be safe and effective when required.”