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Phenazopyridine Side Effects: What to Know

Last reviewed: December 2025

Overview

Phenazopyridine is generally well-tolerated for short-term use. The most notable effect is bright orange or red-orange urine, which is normal and expected. Serious side effects are rare but can occur, especially with prolonged use or in people with kidney problems.

Expected Effects (Not Side Effects)

Orange/Red Urine

This is normal and expected:

  • Urine turns bright orange or red-orange
  • Occurs in everyone taking phenazopyridine
  • Begins shortly after first dose
  • Resolves 24-48 hours after stopping
  • Color intensity depends on hydration level

Important distinctions:

  • Orange = normal drug effect
  • Red with clots = possible blood (seek care)
  • Pink = might be diluted drug or blood (monitor)

Common Side Effects

Gastrointestinal:

  • Stomach upset
  • Nausea
  • Indigestion

Prevention: Take with food to minimize stomach side effects.

Other common effects:

  • Headache
  • Dizziness

These typically resolve on their own and don’t require stopping the medication for short-term use.

Staining Issues

What Gets Stained

  • Urine: Expected orange color
  • Underwear: May permanently stain fabric
  • Contact lenses: Soft lenses can be permanently stained
  • Skin: May cause slight yellow-orange tint with extended use

Prevention

  • Remove contact lenses while taking phenazopyridine
  • Wear underwear you don’t mind staining (or use panty liners)
  • Wash hands thoroughly after handling tablets
  • Stains on fabric may not wash out

Serious Side Effects

Signs of Methemoglobinemia

A rare but serious blood condition:

  • Blue or gray skin color (especially lips, fingernails)
  • Shortness of breath
  • Fatigue
  • Headache
  • Rapid heartbeat
  • Confusion

Seek emergency care immediately if these occur.

Signs of Liver Problems

  • Yellowing of skin or eyes (jaundice)
  • Dark urine (different from orange discoloration)
  • Severe fatigue
  • Upper right abdominal pain
  • Nausea with loss of appetite

Signs of Kidney Problems

  • Decreased urination
  • Swelling
  • Unusual fatigue

Allergic Reactions

  • Skin rash
  • Itching
  • Swelling of face, lips, tongue
  • Difficulty breathing

Stop taking phenazopyridine and seek medical care for any serious side effects.

Risk Factors for Side Effects

Kidney Disease

  • Phenazopyridine is excreted by kidneys
  • Can accumulate to toxic levels
  • Contraindicated in kidney disease
  • Higher risk of methemoglobinemia

G6PD Deficiency

  • Genetic enzyme deficiency
  • Higher risk of hemolytic anemia
  • Should not use phenazopyridine

Extended Use

  • Using beyond 2 days increases risks
  • Liver and kidney effects more likely
  • Skin discoloration can occur

Elderly

  • May be more sensitive to side effects
  • Higher risk of kidney impairment
  • Use lower doses if prescribed

Side Effects vs UTI Symptoms

It can be confusing to distinguish side effects from UTI symptoms:

SymptomDrug Side EffectUTI Symptom
Orange urineYes (expected)No
Burning urinationNo (should improve)Yes
Back painNoYes (possible kidney involvement)
FeverNoYes (infection sign)
NauseaPossiblePossible with kidney infection

If UTI symptoms aren’t improving within 2 days on antibiotics, contact your doctor.

Interference with Lab Tests

Phenazopyridine can affect urine tests:

  • Urine dipstick tests may be inaccurate
  • Urine glucose tests may show false results
  • Ketone tests may be affected
  • Bilirubin tests may be affected

Tell your healthcare provider you’re taking phenazopyridine before any urine tests.

Managing Side Effects

Stomach Upset

  • Always take with food
  • Take with a full glass of water
  • Take after meals

Staining

  • Wear dark underwear or panty liners
  • Remove soft contact lenses
  • Wash hands after handling tablets

Headache

  • Usually mild and temporary
  • OTC pain relievers can help
  • Stay hydrated

When to Stop Taking It

Stop phenazopyridine and contact your doctor if:

  • Symptoms last more than 2 days
  • Fever develops
  • Back or side pain occurs
  • Severe stomach pain
  • Signs of allergic reaction
  • Blue/gray skin discoloration
  • Yellowing of skin or eyes
  • Symptoms worsen instead of improve

After Stopping

  • Orange urine color clears within 24-48 hours
  • All side effects should resolve quickly
  • If effects persist, contact healthcare provider
  • Contact lens staining is permanent (replace lenses)

Sources

  • FDA — Phenazopyridine Safety Information
  • UpToDate — Phenazopyridine: Adverse Effects
  • American Urological Association — UTI Management
  • Drug package inserts (AZO, Pyridium)
Last reviewed: December 2025