There are several possible causes of this, up to and including a side effect of Pentasa (see below for side effects, it is including at the very end).
Pentasa Side Effects - for the Professional
Pentasa
In combined domestic and foreign clinical trials, more than 2100 patients with ulcerative colitis or Crohn's disease received Pentasa therapy. Generally, Pentasa therapy was well tolerated. The most common events (ie, greater than or equal to 1%) were diarrhea (3.4%), headache (2.0%), nausea (1.8%), abdominal pain (1.7%), dyspepsia (1.6%), vomiting (1.5%), and rash (1.0%).
In two domestic placebo-controlled trials involving over 600 ulcerative colitis patients, adverse events were fewer in Pentasa-treated patients than in the placebo group (Pentasa 14% vs placebo 18%) and were not dose-related. Events occurring at 1% or more are shown in the table below. Of these, only nausea and vomiting were more frequent in the Pentasa group. Withdrawal from therapy due to adverse events was more common on placebo than Pentasa (7% vs 4%).
Clinical laboratory measurements showed no significant abnormal trends for any test, including measurement of hematological, liver, and kidney function.
The following adverse events, presented by body system, were reported infrequently (ie, less than 1%) during domestic ulcerative colitis and Crohn's disease trials. In many cases, the relationship to Pentasa has not been established.
Gastrointestinal: abdominal distention, anorexia, constipation, duodenal ulcer, dysphagia, eructation, esophageal ulcer, fecal incontinence, GGTP increase, GI bleeding, increased alkaline phosphatase, LDH increase, mouth ulcer, oral moniliasis, pancreatitis, rectal bleeding, SGOT increase, SGPT increase, stool abnormalities (color or texture change), thirst
Dermatological: acne, alopecia, dry skin, eczema, erythema nodosum, nail disorder, photosensitivity, pruritus, sweating, urticaria
Nervous System: depression, dizziness, insomnia, somnolence, paresthesia
Cardiovascular: palpitations, pericarditis, vasodilation
Other: albuminuria, amenorrhea, amylase increase, arthralgia, asthenia, breast pain, conjunctivitis, ecchymosis, edema, fever, hematuria, hypomenorrhea, Kawasaki-like syndrome, leg cramps, lichen planus, lipase increase, malaise, menorrhagia, metrorrhagia, myalgia, pulmonary infiltrates, thrombocythemia, thrombocytopenia, urinary frequency
The most dangerous reason I can think of is that the inflammation is pushing on your bladder, but that is by no means the only one.
I'm not sure why you don't just call your doctor's office and have them ask the doctor if this is anything to be concerned about? My doctor prescribed this for me and told me to call if I am concerned about any symptoms or have questions. There is no harm in asking as this is a change in your body's behavior since being on the medication.
