AZO (Phenazopyridine) Use in Pregnancy
Phenazopyridine is safe to use during pregnancy for symptomatic relief of urinary tract infection symptoms, with no evidence of increased fetal malformations. 1
Safety Profile During Pregnancy
Existing data indicate that phenazopyridine exposure during pregnancy is not associated with increased risk of fetal malformations, based on available safety evidence. 1
Phenazopyridine crosses the placenta into the fetal compartment, but this does not translate to teratogenic risk in clinical practice. 2
The medication has been studied in pregnant women undergoing amniocentesis without adverse maternal or fetal effects documented. 2
Recommended Dosing and Duration
The standard adult dose is 200 mg orally three times daily for symptomatic relief, typically used for 2 days while awaiting antibiotic effect. 3
Limit duration to 2 days maximum when used as adjunctive therapy with antibiotics for acute cystitis, as this provides adequate symptomatic relief while minimizing exposure. 3
A single dose of 200 mg has been shown effective for rapid symptom improvement in acute uncomplicated cystitis. 4
Clinical Efficacy for Symptom Relief
Phenazopyridine provides significant analgesic effect, reducing pain severity by 53-57% within 6 hours of administration compared to placebo or alternative agents. 3, 4
The medication effectively relieves dysuria, urinary frequency, and general discomfort associated with UTI, with most patients reporting "significant improvement" within 6 hours. 4
When combined with fosfomycin for acute cystitis treatment, phenazopyridine achieved 97.4% clinical cure rates and resolved symptoms 30% faster than alternative regimens. 3
Important Clinical Caveats
Phenazopyridine is purely symptomatic therapy and does not treat the underlying infection—concurrent antibiotic therapy is mandatory for UTI treatment. 3, 4
The medication causes characteristic orange-to-red discoloration of urine, which should be explained to patients to avoid alarm. 2
Rare adverse effects include nausea (1.3% incidence) and, very rarely, sulfhemoglobinemia in predisposed patients (those with chronic constipation or other sources of hydrogen sulfide). 3, 5
Sulfhemoglobinemia presents as cyanosis that does not respond to oxygen or methylene blue therapy; discontinue phenazopyridine immediately if suspected. 5
Antibiotic Selection in Pregnancy
Safe antibiotic options for UTI in pregnancy include penicillins, cephalosporins, and nitrofurantoin, all of which are not associated with increased fetal malformations. 1
Avoid trimethoprim-sulfamethoxazole during the first trimester due to antifolate effects associated with neural tube defects. 1
Fluoroquinolones are contraindicated throughout pregnancy. 6