I have been on and off Budesonide for over 24 years with microscopic colitis. Typically I'd get a flare every two years. For most of that time the effectiveness did not decrease when I went off and on. I was on the 9mg for 2 weeks, 6 mg for 2 weeks, then 3 mg for 2 weeks, and it worked.

However, during the last couple years I've been experiencing more frequent flares and the Budesonide has lost it's effectiveness. I've been on 9mg per day since January with little relief, and it's frustrating and worrisome. So yes, it appears Budesonide can lose it's effectiveness.