The purpose of this study is to demonstrate the efficacy of budesonide for the treatment of active incomplete microscopic colitis.

Inclusion Criteria:

• Histologically established diagnosis of incomplete microscopic colitis (MCi)
• History of chronic non-bloody, watery diarrhoea
• Clinically active disease

Exclusion Criteria:

• Other significant abnormalities in colonoscopy
• Infectious cause of diarrhoea
• Clinical suspicion of drug-induced diarrhoea
• Prior and present MC
• History of bowel resection
• Radiation therapy of the abdominal or pelvic region
• Positive antibody titres for celiac disease
• Untreated active thyroid dysfunction
• Any severe concomitant cardiovascular, renal, endocrine, or psychiatric disorder reducing life expectancy
• Abnormal hepatic function
• Tuberculosis, hypertension, diabetes mellitus, osteoporosis, peptic ulcer disease, glaucoma, cataract, or infection if careful medical monitoring is not ensured
• History of colorectal cancer
• History of cancer (other than colorectal) in the last 5 years
• Therapy with immunomodulators/budesonide or other steroids/antibiotics/anti-diarrhoeal drugs
• Current or intended pregnancy or breast-feeding
• Doubt about the patient's cooperation, e.g. because of addiction to alcohol or drugs
• Participation in another clinical trial within the last 30 days, simultaneous participation in another clinical trial, or previous participation in this trial