Methylene blue will most likely cause your urine or stools to appear blue or green in color. This is a normal side effect of the medication and will not cause any harm.
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using  Urogesic-Blue and call your doctor at once if you have:
severe dizziness, blurred vision, fast heart rate;
agitation, confusion, feeling restless or excited;
painful or difficult urination; or
shortness of breath.
Older adults may be more likely to have side effects from this medication.
Common side effects may include:
mild dizziness;
dry mouth; or
nausea, vomiting.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Urogesic Blue side effects (more detail)
