Inclusion Criteria:

• Voluntarily sign written informed consent.
• Male or non-pregnant and non-lactating females ≥18 years of age.
• Confirmed diagnosis (by endoscopy procedure) of active, mild to moderate ulcerative proctitis or proctosigmoiditis extending no further than 40cm from the anal verge.
• Must possess a baseline MMDAI score between 5 and 10.
• Visible blood in stool.

Exclusion Criteria:

• History or current diagnosis of Crohn's disease and indeterminate colitis.
• Prior gastrointestinal surgery except appendectomy and hernia.
• Concomitant active gastrointestinal disease or distortion of intestinal anatomy.
• History of diverticulitis, collagenous colitis, celiac disease, recurrent pancreatic or known gallbladder disease.
• Uncontrolled, previously diagnosed type 1 or 2 diabetes mellitus.
• Uncontrolled abnormal thyroid function.
• Unstable significant cardiovascular, endocrine, neurologic or pulmonary disease.
• Hemoglobin levels < 7.5 g/dL.
• History of sclerosing cholangitis, cirrhosis, or hepatic impairment.
• Renal disease manifested by > 2.0mg/dL serum creatinine.
• History of avascular hip necrosis, active tuberculosis, ocular herpes simplex or ocular varicella zoster, malignant disease, and HIV or hepatitis B or C.
• Adrenal insufficiency.
• Active systemic or cutaneous infection or toxic megacolon, fistula, perforation or abscess.
• History of uncontrolled psychiatric disorders or seizure disorders.
• History of asthma requiring ongoing use of inhaled steroids.
• Recent history of drug or alcohol abuse.
• Positive stool test for bacterial pathogens, C diff or O&P.
• Vaccination within 28 days prior to Randomization.
• Allergies to budesonide or to any other items used in its preparation.
• Participation in another clinical trial in the past 30 days.
• Pregnant or at risk of pregnancy.
• Taking a prohibited medication. Some medications to treat UP/UPS are prohibited during participation in the study, including laxatives and anti-diarrhea medications; however, oral 5-ASA agents at doses up to 4.8g/day and daily fiber supplements are allowed. Other medications (e.g., antibiotics, anti-seizure and anti-coagulant medicines) are also prohibited.