I am an adult male (40 years old) with cystic fibrosis. I have never ever detected an odour specifically regarding my DISEASE, however as in the first answer you received from Diane (I think her name might have been--in fact, it probably still IS her name), there may be more to it than just the disease itself.There ARE several medicines, mostly antibiotics, upon which I have been placed from time to time, that HAVE, in fact, created different odours in and about my person. One antibiotic in particular is called ceftazadime. It's an i.v. antibiotic, but it makes my urine and breath smell something fierce. In fact, interestingly enough (not that you really want to know this), ceftazadime makes pee smell exactly like a bowl of Kellogg's Sugar Smacks breakfast cereal, no kidding. I think that cereal nowadays may be called something else---Maybe "Smacks" or something to that effect (I imagine the word "sugar" didn't exactly draw a large customer base in this health-conscious society of ours).Anyway, another drug which makes my mouth and breath smell so bad it could knock a sick buzzard off a dump truck is an antibiotic called tobramycin, another i.v. med. It isn't the drug though, that offers the odour. What DOES cause the odour is this: when one is put on potent antibiotics or maybe several antibiotics at one time, the drugs can work too well. What I mean is this: Potent antibiotics are intended to kill bad bacteria in one's body. Unfortunatey during the process, they often kill the GOOD bacteria in your body as well. One place in particular that's teaming with bacteria is---you got it---one's mouth. When this happens to me, I tend to get a mouth infection called "thrush." Thrush (that's not the technical name) can be very painful and encompassing. But it can also be mild and virtually undetected. In my case, the problem is that Thrush, regardless of whether or not I've a mild or serious or undetected case, makes for some potent parlance, Herculean halitosis, puke-inducing prattle.It seems, by your letter however, that he tends to get the foul breath when he's NOT on antibiotics. Cystic Fibrosis is, as you know, also a disease that affects the belly as well as the lungs. Bad digestion, caused by anything, is most often the cause of chronic halitosis. So it may very well be that when he is sicker (i.e.: not on antibiotics), he is not digesting his food as efficiently and thus bringing up his wicked wind, so to speak.This probably doesn't help you much, but maybe someone might benefit from the information above.Over and out.pfrenzel@mn.rr.com