Apr 4, 2018 - 4:51 AM
It would probably be worthwhile consulting your doctor to quantify the severity of your asthma - people suffering long standing severe asthma may have chronic pulmonary disease as well, and probably shouldn't go above 8,000 feet. The Jungfraujoch railway station is 11,332. If your asthma is less severe and you can control it using a nebuliser, you could possibly go that high without any problems, but it would be a good idea to spend a few days acclimatising in Wengen before going higher. Your ability to cope with the altitude in Wengen is no indication of how you will handle the higher altitude, so the more time you can spend acclimatising, the better.
I am not a doctor. I got this information from my copy of Medicine for Mountaineering which is now quite old and possibly out of date. The best advice I could give is to see your doctor and take your nebuliser and a prescription for a replacement when you travel.
Hope this helps