A quick google check reveals that blood in the urine is a common side effectof Rituxan. This is from the Mayo Clinic website, a fairly reliable source:
Rituximab (Intravenous Route)
Side Effects
Along with its needed effects, a medicine 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 or nurse immediately if any of the following side effects occur:
More common
* Abdominal or stomach pain
* Black, tarry stools
* Bleeding gums
* Bloating or swelling of the face, arms, hands, lower legs, or feet
* Blood in the urine or stools
* Blurred vision
* Body aches or pain
* Chest pain
* Confusion
* Convulsions
* Cough or hoarseness
* Difficulty with breathing
* Dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
* Drowsiness
* Dry mouth
* Ear congestion
* Fever and chills
* Flushed, dry skin
* Fruit-like breath odor
* Headache
* Hives or welts
* Increased hunger
* Increased thirst
* Increased urination
* Itching
* Large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
* Lower back or side pain
* Nausea
* Nervousness
* Noisy breathing
* Pain or tenderness around the eyes and cheekbones
* Painful or difficult urination
* Pale skin
* Pinpoint red spots on the skin
* Pounding in the ears
* Shortness of breath
* Skin rash
* Slow or fast heartbeat
* Sneezing
* Sore throat
* Sores, ulcers, or white spots in the mouth or on the lips
* Stuffy or runny nose
* Sweating
* Swelling of the tongue or throat
* Swollen glands
* Tightness of the chest
* Tingling of the hands or feet
* Troubled breathing with exertion
* Unusual bleeding or bruising
* Unusual tiredness or weakness
* Unusual weight gain or loss
* Vomiting
Less common
* Blistering, peeling, or loosening of the skin
* Blisters in the mouth
* Blisters on the trunk, scalp, or other areas
* Burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feeling
* Burning, tingling, numbness or pain in the hands, arms, feet, or legs
* Decreased frequency and amount of urination
* Diarrhea
* Difficulty with moving
* Discouragement
* Feeling sad or empty
* Irregular heartbeat
* Irritability
* Joint or muscle pain
* Loss of appetite
* Loss of interest or pleasure
* Muscle cramps
* Muscle pain or stiffness
* Numbness or tingling in the hands, feet, or lips
* Pain at the injection site
* Pain, swelling, or redness in the joints
* Red skin lesions, often with a purple center
* Red, itchy lining of the eye
* Redness of the face, neck, arms, and occasionally, upper chest
* Stabbing pain
* Trouble concentrating
* Trouble sleeping
Incidence not known
* Abdominal or stomach cramps
* Blue-yellow color blindness
* Blurred vision or other change in vision
* Burning or stinging of the skin
* Decreased vision
* Dilated neck veins
* Dry cough
* Extreme fatigue
* Eye pain, tearing
* Feeling of discomfort, illness, or weakness
* Irregular breathing
* Nosebleed
* Painful cold sores or blisters on the lips, nose, eyes, or genitals
* Sensitivity of the eye to light
* Severe abdominal or stomach pain
* Severe vomiting, sometimes with blood
* Sores, welting, or blisters
* Swelling, stiffness, redness, or warmth around many joints
* Swollen and inflamed joints
* Swollen lymph glands
* Vision loss
Some side effects 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
* Fear
* Increased cough
* Lack or loss of strength
* Night sweats
* Throat irritation
Less common
* Agitation or anxiety
* Change in taste
* Dry eyes
* Excessive muscle tone
* Feeling of constant movement of self or surroundings
* Heartburn
* Increase in body movements
* Lightheadedness
* Muscle tension
* Pain or redness at the injection site
* Sensation of spinning
* Sleepiness
* Swelling of the stomach
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.