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Colazal Side Effects

Generic Name: balsalazide

Note: This document contains side effect information about balsalazide. Some of the dosage forms listed on this page may not apply to the brand name Colazal.

For the Consumer

Applies to balsalazide: oral capsule

Side effects requiring immediate medical attention

Along with its needed effects, balsalazide (the active ingredient contained in Colazal) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking balsalazide:

More common

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

Side effects not requiring immediate medical attention

Some side effects of balsalazide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

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

For Healthcare Professionals

Applies to balsalazide: oral capsule, oral tablet


Very common (10% or more): Abdominal pain upper (17%), vomiting (17%), abdominal pain (12%), diarrhea (11%)

Common (1% to 10%): Flatulence, dyspepsia, dry mouth, constipation, colitis ulcerative, hematochezia, nausea, stomatitis

Frequency not reported: Defecation urgency, hard feces, gastroesophageal reflux disease, gastroenteritis

Postmarketing reports: Pancreatitis[Ref]

Nervous system

Very common (10% or more): Headache (15%)

Frequency not reported: Dizziness, lethargy[Ref]


Very common (10% or more): Pyrexia (11%)

Common (1% to 10%): Fatigue, fever, flu-like disorder, pyrexia

Frequency not reported: Malaise, pain, pyrexia[Ref]


Common (1% to 10%): Arthralgia, musculoskeletal pain, myalgia, cramps

Frequency not reported: Back pain[Ref]


Common (1% to 10%): Pharyngolaryngeal pain, coughing

Postmarketing reports: Alveolitis, pleural effusion[Ref]


Frequency not reported: Increased aspartate aminotransferase

Postmarketing reports: Elevated liver enzymes (AST, ALT, GGT, LDH, alkaline phosphatase), elevated bilirubin, jaundice, cholestatic jaundice, cirrhosis, hepatocellular damage including liver necrosis and liver failure, Kawasaki-like syndrome including hepatic dysfunction[Ref]


Common (1% to 10%): Anemia[Ref]


Frequency not reported: Increased blood pressure, increased heart rate

Postmarketing reports: Myocarditis, pericarditis, vasculitis[Ref]


Postmarketing reports: Renal failure, interstitial nephritis[Ref]


Frequency not reported: Erythema nodosum, rash, face edema

Postmarketing reports: Alopecia, pruritus[Ref]


Common (1% to 10%): Nasopharyngitis, rhinitis, pharyngitis, urinary tract infection, influenza

Frequency not reported: Upper respiratory infection

Postmarketing reports: Pneumonia (with and without eosinophilia)[Ref]


Common (1% to 10%): Anorexia[Ref]


Common (1% to 10%): Insomnia[Ref]


Common (1% to 10%): Dysmenorrhea[Ref]


1. "Product Information. Giazo (balsalazide)." Valeant Pharmaceuticals, Costa Mesa, CA.

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

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.