The characteristic orange-colored urine after taking Pyridium<unk>  produces a vivid color change in urine, typically to a dark orange to reddish color. This effect is common and harmless, and indeed a key indicator of the presence of the medication in the body. Users of<unk>  are warned not to wear contact lenses, as<unk>  has been known to permanently discolor contact lenses and fabrics. It also tends to leave an orange-yellow stain on surfaces it comes in contact with. Some may be mistakenly concerned that this indicated blood in the urine.<unk>  can also cause headaches, upset stomach (especially when not taken with food), or dizziness. Less frequently it can cause a pigment change in the skin or eyes, to a noticeable yellowish color. This is due to a depressed excretion via the kidneys causing a buildup of the medication in the skin, and normally indicates a need to discontinue usage. Other such side effects include fever, confusion, shortness of breath, skin rash, and swelling of the face, fingers, feet, or legs. Long-term use may cause yellowing of nails.<unk>  should be avoided by people with glucose-6-phosphate dehydrogenase deficiency, because it can cause hemolysis (destruction of red blood cells) due to oxidative stress. It has been reported to cause methemoglobinemia after overdose and even normal doses. In at least one case the patient had pre-existing low levels of methemoglobin reductase, which likely predisposed her to the condition. It has also been reported to cause sulfhemoglobinemia.<unk>  is an azo dye. Other azo dyes, which were previously used in textiles, printing, and plastic manufacturing, have been implicated as carcinogens that can cause bladder cancer. While<unk>  has never been shown to cause cancer in humans, evidence from animal models suggests that it is potentially carcinogenic. Pregnancy This medication is pregnancy category B. This means that the medication has shown no adverse events in animal models, but no human trials have been conducted. It is not known if<unk>  is excreted in breast milk.
Phenazopyridine
Imidazopyridine
Warfarin
Aspirin
Quinidine
Amiodarone
Clofibride
Clopidogrel