Skip to Content

Balsalazide Side Effects

For the Consumer

Applies to balsalazide: oral capsule, oral tablet

In addition to its needed effects, some unwanted effects may be caused by balsalazide. In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking balsalazide:

More common:
  • Bloody diarrhea
  • fever
  • skin rash
Less common:
  • Bladder pain
  • bloody or cloudy urine
  • bloody stools
  • difficult, burning, or painful urination
  • frequent urge to urinate
  • heavy bleeding
  • lower back or side pain
  • Difficult or labored breathing
  • shortness of breath
  • tightness in the chest
  • wheezing
Incidence not known:
  • Abdominal or stomach pain or tenderness
  • chills
  • clay colored stools
  • dark urine
  • decreased appetite
  • decreased frequency or amount of urine
  • dizziness
  • general feeling of tiredness or weakness
  • headache
  • increased blood pressure
  • increased thirst
  • itching
  • joint pain
  • light-colored stools
  • loss of appetite
  • nausea and vomiting
  • stomach pain, continuing
  • swelling of the face, fingers, feet, or lower legs
  • unpleasant breath odor
  • unusual tiredness or weakness
  • vomiting of blood
  • weight gain
  • yellow eyes or skin

Minor Side Effects

Some of the side effects that can occur with balsalazide may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Diarrhea
  • mild headache
  • muscle aches
  • sore throat
  • stuffy or runny nose
Less common:
  • Acid or sour stomach
  • belching
  • bloated or full feeling
  • body aches or pain
  • bone pain
  • congestion
  • constipation
  • coughing
  • cramps
  • difficulty with moving
  • dry mouth
  • dryness of the throat
  • excess air or gas in the stomach or intestines
  • general feeling of discomfort or illness
  • heartburn
  • hoarseness
  • indigestion
  • muscle pain or stiffness
  • pale skin
  • passing of gas
  • shivering
  • sleeplessness
  • sneezing
  • stomach discomfort or upset
  • sweating
  • swelling or inflammation of the mouth
  • swollen joints
  • tender, swollen glands in the neck
  • trouble with sleeping
  • trouble with swallowing
  • troubled breathing with exertion
  • unable to sleep
  • unusual bleeding or bruising
  • voice changes
  • weight loss
  • Back pain
  • ear congestion
  • loss of appetite
  • loss of voice
  • pain in the ankles or knees
  • painful, red lumps under the skin, mostly on the legs
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
Incidence not known:
  • Hair loss or thinning of the hair

For Healthcare Professionals

Applies to balsalazide: oral capsule, oral tablet


During clinical trials, the most common side effects reported with the capsule formulation were headache, abdominal pain, diarrhea, nausea, vomiting, respiratory infection, and arthralgia. Some side effects (including abdominal pain, fatigue, and nausea) were reported more often in women than in men. Abdominal pain, rectal bleeding, and anemia can be part of the clinical presentation of ulcerative colitis.

During a clinical trial, the most common side effects reported in male patients taking the tablet formulation were headache, nasopharyngitis, anemia, diarrhea fatigue, pharyngolaryngeal pain, and urinary tract infection. Most side effects were mild to moderate in severity. The most common serious side effects were gastrointestinal disorders, which were primarily associated with symptoms of ulcerative colitis.[Ref]


Gastrointestinal side effects have included abdominal pain (up to 6%), diarrhea (up to 5%), nausea (5%), vomiting (up to 4%), dyspepsia (2%), flatulence (up to 2%), anorexia (2%), dry mouth (up to 1%), constipation (up to 1%), defecation urgency (less than 1%), hard feces (less than 1%), gastroesophageal reflux disease (less than 1%), and gastroenteritis (less than 1%). Pancreatitis has been reported during postmarketing experience.[Ref]


Musculoskeletal side effects have included arthralgia (up to 4%), musculoskeletal pain (2.4%), myalgia (up to 1%), and back pain (less than 1%).[Ref]


Respiratory side effects have included nasopharyngitis, respiratory infection (4%), pharyngolaryngeal pain (3.7%), coughing (2%), pharyngitis (2%), rhinitis (2%), dyspnea (less than 1%), and upper respiratory infection (less than 1%). Pleural effusion, pneumonia (with and without eosinophilia), and alveolitis have been reported during postmarketing experience.[Ref]

Nervous system

Nervous system side effects have included headache (8%), insomnia (up to 2.4%), lethargy (less than 1%), and dizziness (less than 1%).[Ref]


Hepatic side effects have included elevated aspartate aminotransferase (less than 1%). Hepatotoxicity, including elevated liver function tests (SGOT/AST, SGPT/ALT, GGT, LDH, alkaline phosphatase, bilirubin), jaundice, cholestatic jaundice, cirrhosis, hepatocellular damage (including liver necrosis and liver failure), and Kawasaki-like syndrome (including hepatic function changes) have been reported during postmarketing experience of products that contain (or are metabolized to) mesalamine; some cases were fatal.[Ref]


Hematologic side effects have included anemia (3.7%), thrombocythemia, and prothrombin changes. A higher incidence of blood dyscrasias (i.e., neutropenia and pancytopenia) has been reported during uncontrolled clinical trials and postmarketing experience in patients 65 years or older receiving mesalamine-containing products.[Ref]


Cardiovascular side effects have included increased blood pressure (less than 1%), increased heart rate (less than 1%), hypertension, palpitations, and bradycardia. Myocarditis, pericarditis, and vasculitis have been reported during postmarketing experience.[Ref]


Renal side effects have included renal failure and interstitial nephritis during postmarketing experience.


Other side effects have included fatigue (up to 2%), fever (2%), cramps (1%), influenza-like disorder (1%), pyrexia (less than 1%), face edema (less than 1%), malaise (less than 1%), pain (less than 1%), and swelling (less than 1%).


Genitourinary side effects have included urinary tract infection (up to 3.7%).


Dermatologic side effects have included erythema nodosum (less than 1%) and rash (less than 1%). Pruritus and alopecia have been reported during postmarketing experience.[Ref]


1. "Product Information. Colazal (balsalazide)" Salix Pharmaceuticals, Palo Alto, CA.

2. Green JR, Lobo AJ, Holdsworth CD, Leicester RJ, Gibson JA, Kerr GD, Hodgson HJ, Parkins KJ, Taylor MD "Balsalazide is more effective and better tolerated than mesalamine in the treatment of acute ulcerative colitis. The Abacus Investigato Group [see comments." Gastroenterology 114 (1998): 15-22

3. Prakash A, Spencer CM "Balsalazide." Drugs 56 (1998): d83-9;isc. 90

4. Loftus EV, Kane SV, Bjorkman D "Safety of 5-aminosalicylic acid agents in the treatment of ulcerative colitis: a systematic review." Am J Gastroenterol 98(9S) (2003): S249

5. Kounis GN, Kouni SA, Chiladakis JA, Kounis NG "Comment: Mesalamine-Associated Hypersensitivity Myocarditis in Ulcerative Colitis and the Kounis Syndrome (February)." Ann Pharmacother 43 (2009): 393-4

Not all side effects for balsalazide may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.