Dig into the science of inhalers, and find out how these devices treat common respiratory conditions like asthma and COPD. -- Inhalers are mainly used to treat two conditions: asthma and chronic obstructive pulmonary disease, or COPD. And there are two main types: preventative inhalers and rescue inhalers. Preventative inhalers can be used every day to control symptoms, while rescue inhalers are