IMO, I think it's very important that kids know 'what' they have. Everyone else that is important in his life knows that he has it (relatives, your friends, his childcare providers if he has any, his doctors. Eventually someone is going to say something in his presence that makes it more obvious 'Luke has cf' ...it would probably be better coming from you first.
It's completely natural and normal for a kid to want to be 'done' with medicine (or anything they don't like, for that matter.) And normally they get to be 'done' with something; they start an abx and eventually finish it, etc. They hurt themselves, need treatment for it, eventually it gets better. And so they want to hear 'eventually this will go away.' The 'this is how it is' approach, depending on how we've gone into things from the start, isn't right for everyone; and will depend a lot on even how we as adults even look at the disease, if that makes sense- and we all are different in that respect. All I can suggest there is finding a way to work it in gradually.
Wording it like 'You have something called Cystic Fibrosis (like X has allergies, and Y has to wear glasses, try to come up with people he knows with health conditions he understands.) ... and because of your cf, you need to take the yucky medicine and use your vest and take your enzymes for your lungs to work as well as they should and for your tummy to digest your food without getting a stomachache. ...But Dr. Carter is working on it (go in as you've been saying.) That way it can be worked in very gradually, and as he gets older more explanation can be given as needed for how long 'those treatments' are going to have to continue for him.
As others have said... prognosis or anything like that at age 4? That doesn't seem necessary at all- unless he comes to you and asks specific questions! (and that wouldn't be unheard of, realistically speaking, in the next couple years- both due to insensitive people and the fact that many kids- meaning healthy kids! do go through phases of worry about 'bad things happening to them' or even death, quite young, and adding a disease to that will potentially make such a phase more problematic.) Then you have to come up with something... but I'd sure stress the positive then. *the only reason I even included this in my post is because people have misunderstood my being 'matter of fact' about the dx itself with some kind of 'tell your very young child scary things' approach. I don't believe it's the same thing at all.*
Since you ask for personal experience: Emily has multiple medical dx'es and so by the time we learned about her CF we'd been dealing with medical stuff for 5yrs. We've always been forthcoming with her about them and I never really felt I had a choice in the matter. She was dx'ed with seizures when she was 2 and have always been open about it around her and to her. My mil used to be horrified about it... I would tell her, what's worse? Telling her she has seizures, or not telling her and letting her go through them and not knowing what was happening to her, and making her take medicine and not knowing why? I've also been honest with her about her developmental disabilities (in an appropriate way) in an effort to try to help her understand why things are hard for her... she certainly hears about them in much less flattering terms from others so the best thing I can do is be honest with her. The same thing goes now with her CF. The best thing we can do is offer our children the truth, in simple, compassionate terms... since eventually they will hear all about it from others- and often not in a way we'd choose. Now, that has just been what's worked best for us... we all have to do what works best for our own families. So much of Emily's daily existence is affected by her medical conditions so that affects my choices.
It's completely natural and normal for a kid to want to be 'done' with medicine (or anything they don't like, for that matter.) And normally they get to be 'done' with something; they start an abx and eventually finish it, etc. They hurt themselves, need treatment for it, eventually it gets better. And so they want to hear 'eventually this will go away.' The 'this is how it is' approach, depending on how we've gone into things from the start, isn't right for everyone; and will depend a lot on even how we as adults even look at the disease, if that makes sense- and we all are different in that respect. All I can suggest there is finding a way to work it in gradually.
Wording it like 'You have something called Cystic Fibrosis (like X has allergies, and Y has to wear glasses, try to come up with people he knows with health conditions he understands.) ... and because of your cf, you need to take the yucky medicine and use your vest and take your enzymes for your lungs to work as well as they should and for your tummy to digest your food without getting a stomachache. ...But Dr. Carter is working on it (go in as you've been saying.) That way it can be worked in very gradually, and as he gets older more explanation can be given as needed for how long 'those treatments' are going to have to continue for him.
As others have said... prognosis or anything like that at age 4? That doesn't seem necessary at all- unless he comes to you and asks specific questions! (and that wouldn't be unheard of, realistically speaking, in the next couple years- both due to insensitive people and the fact that many kids- meaning healthy kids! do go through phases of worry about 'bad things happening to them' or even death, quite young, and adding a disease to that will potentially make such a phase more problematic.) Then you have to come up with something... but I'd sure stress the positive then. *the only reason I even included this in my post is because people have misunderstood my being 'matter of fact' about the dx itself with some kind of 'tell your very young child scary things' approach. I don't believe it's the same thing at all.*
Since you ask for personal experience: Emily has multiple medical dx'es and so by the time we learned about her CF we'd been dealing with medical stuff for 5yrs. We've always been forthcoming with her about them and I never really felt I had a choice in the matter. She was dx'ed with seizures when she was 2 and have always been open about it around her and to her. My mil used to be horrified about it... I would tell her, what's worse? Telling her she has seizures, or not telling her and letting her go through them and not knowing what was happening to her, and making her take medicine and not knowing why? I've also been honest with her about her developmental disabilities (in an appropriate way) in an effort to try to help her understand why things are hard for her... she certainly hears about them in much less flattering terms from others so the best thing I can do is be honest with her. The same thing goes now with her CF. The best thing we can do is offer our children the truth, in simple, compassionate terms... since eventually they will hear all about it from others- and often not in a way we'd choose. Now, that has just been what's worked best for us... we all have to do what works best for our own families. So much of Emily's daily existence is affected by her medical conditions so that affects my choices.