Parents and carers of children with asthma in Bristol, north Somerset and south Gloucestershire, are being advised to make sure their kids start using their inhalers ahead of their return to school.
Doctors say evidence shows that using inhalers preventatively - before symptoms of wheezing occur - will reduce the risk of becoming unwell.
Parents and guardians are also being warned to be alert for signs that their condition may be deteriorating.
This comes after a charity found that the number of youngsters admitted to hospital "skyrockets" as they go back to school.
Children between the ages of five and 19 across England, Scotland and Wales are 1.7 times more likely to be rushed to hospital following an asthma attack in September compared with August, Asthma UK said.
children were admitted to hospital because of their asthma in September last year.
The charity said children were at much greater risk of having a potentially fatal asthma attack when they were back in school, due to the increased exposure to triggers such as cold and flu viruses.
Asthma UK is urging parents to spot the warning signs that their child's asthma is getting worse, and to know what to do if their child is having an asthma attack.
Last year, 2,422 children were admitted to hospital because of their asthma in September compared with 892 in August. The charity said similar increases had been noted in previous years.