Phenazopyridine Side Effects: What to Expect and When to Call Your Doctor

Phenazopyridine (brand name Pyridium, OTC brands AZO and Uristat) is generally well-tolerated when taken correctly for the recommended 2-day course. However, it has some distinctive side effects—including the alarming-looking orange urine—that patients should be prepared for. Here's a clear breakdown of what's normal, what to watch for, and what requires medical attention.

The Most Common Side Effect: Orange Urine

The most noticeable side effect of phenazopyridine is vivid orange or reddish-orange urine. This happens because phenazopyridine is an azo dye—the same class of chemicals used to color textiles. About 65% of each oral dose is excreted unchanged into your urine, where it produces this intense color change.

This is expected, harmless, and not a sign of blood in the urine. It will stop as soon as you finish the medication. However, it can:

Permanently stain soft contact lenses (avoid wearing them while taking this medication)

Stain fabric, clothing, and bedding (wash promptly with cold water)

Produce false results on urine dipstick tests (tell your provider you are taking it before any urine testing)

Common Side Effects (Usually Not Serious)

These side effects may occur during the 2-day treatment course and typically resolve on their own:

Stomach upset or nausea — Take phenazopyridine with food or after a meal to reduce GI discomfort

Headache — Generally mild and transient

Dizziness — Uncommon but reported

Orange-red discoloration of urine — Expected and harmless (see above)

Serious Side Effects: When to Stop and Call Your Doctor

The following side effects are uncommon but require prompt medical attention. Stop phenazopyridine and contact your healthcare provider immediately if you experience any of these:

Yellowing of skin or whites of the eyes (jaundice-like appearance): This indicates drug accumulation due to impaired kidney function. The medication cannot be cleared properly and is building up in your body. Stop immediately and call your provider.

Sudden decrease in urine output: May indicate kidney toxicity from drug accumulation.

Shortness of breath, confusion, or bluish discoloration of lips/fingernails: May indicate methemoglobinemia—a rare but serious condition in which phenazopyridine reduces the blood's ability to carry oxygen. Seek emergency care immediately.

Severe back or abdominal pain: May indicate the UTI has progressed to a kidney infection (pyelonephritis)—not caused by phenazopyridine, but a sign you need more aggressive treatment.

Skin rash, itching, hives, or facial swelling: Signs of an allergic reaction. Seek care immediately.

Fever: Not a side effect of phenazopyridine itself. Fever with UTI symptoms may indicate a kidney infection—contact your provider promptly.

Who Is at Highest Risk for Serious Side Effects?

People with kidney disease: Phenazopyridine is excreted by the kidneys. Reduced kidney function causes dangerous drug accumulation. Phenazopyridine is contraindicated in renal insufficiency.

People with G6PD deficiency: An inherited enzyme deficiency that increases the risk of hemolytic anemia (destruction of red blood cells) with phenazopyridine.

Elderly patients: Age-related decline in kidney function increases accumulation risk. Yellowing of the skin or eyes in an elderly patient on phenazopyridine is a red flag.

People taking phenazopyridine longer than 2 days: Longer use significantly increases risk of accumulation and all serious side effects. Do not exceed 2 days of use.

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How to Minimize Side Effects

Always take with food or after a meal to reduce stomach upset

Take with a full glass of water

Do not use for more than 2 days when taking alongside an antibiotic

Do not wear soft contact lenses—the orange dye permanently stains them

Tell any lab or provider you are taking phenazopyridine before urine testing

For information on phenazopyridine interactions with other medications, see: Phenazopyridine Drug Interactions: What to Avoid.