What to do if i had promethazine dm, and i have asthma. i'm afraid to go to sleep. what's going to happen?

Not recommended.: Promethazine is best known for decreasing nausea and vomiting. It is known as a first-generation antihistamine and there are studies that show antihistamines can worsen current wheezing attacks. Part of this is from the drying effect it has on the airway. It is a strong sedative and can cause respiratory depression. If you are currently wheezing, use your rescue inhaler. Not wheezing, no worry