Common Azo side effects may include headache, dizziness, or upset stomach. Serious Azo side effects. Get emergency medical help if you have any of these signs of an allergic reaction hives, difficulty breathing, swelling of your face, lips, tongue, or throat. Azo may cause other serious side effects.

Learn about the side effects of Azo-Standard (phenazopyridine), from common to rare, for consumers and healthcare professionals.

Azo-Standard may cause serious side effects. Stop using Azo-Standard and call your doctor at once if you have: little or no urinating; swelling, rapid weight gain; confusion, loss of appetite, pain in your side or lower back; fever and

Tell your doctor right away if you have any serious side effects, including: yellowing skin / eyes, dark urine, signs of kidney problems (such as change in the amount of urine, bloody urine),...