Will having asthma affect me passing a medical?

Dpnds on definitions: Is the 'medical' a checkup, an insurance physical, an aviation medical exam (been an ame since 1997). Importantly, is the diagnosis of asthma correct--not all that wheezes is asthma. How severe is it? Is it well controlled? Do u know how and when to take the oral or inhaler medication-many asmtcs do not, and many don't realize that a wheeze-free existence is the goal, with rescue inhaler prn....

No: Not necessarily - asthma is very common and can affect otherwise health people. Many of my patients with asthma are able to pass medical insurance exams/tests without any change in their payments / premiums.