Phenazopyridine 100mg tablets
Requires a prescription from a doctor or prescriber
Phenazopyridine, also known as Pyridium, is a urinary tract analgesic used for the short-term management of urinary tract irritation and its associated unpleasant symptoms such as burning and pain during urination.
Official documents, adverse reaction reporting, and safety monitoring
Report a side effect
Submit a Yellow Card report to the MHRA
Safety monitoring data
Yellow Card reports
The MHRA Yellow Card scheme collects reports of suspected side effects from healthcare professionals and patients. View the Drug Analysis Profile (iDAP) for real-world adverse reaction data.
View Drug Analysis Profile
Suspected adverse reactions reported for Phenazopyridine
Browse all iDAP reports
Interactive Drug Analysis Profiles for all medicines
Report a side effect
Submit a Yellow Card report to the MHRA
Data from the MHRA Yellow Card scheme. A reported reaction does not necessarily mean the medicine caused it. Contains public sector information licensed under the Open Government Licence v3.0.
EudraVigilance
The European Medicines Agency (EMA) collects suspected adverse reaction reports from across the EU/EEA through the EudraVigilance system. Search for safety data on this medicine.
Search EudraVigilance database
Browse substances A–Z in the European adverse reaction database
About EudraVigilance
Learn about EU pharmacovigilance and safety monitoring
EudraVigilance data is published by the European Medicines Agency (EMA). A suspected adverse reaction is not necessarily caused by the medicine.
2 branded products available
Therapeutically similar medicines
Similarity is based on WHO Anatomical Therapeutic Chemical (ATC) classification and on a factual NHS dm+d therapeutic-grouping code prefix. Source data: NHS dm+d via TRUD (OGL v3.0), WHO ATC/DDD Index.
Check stock at pharmacies and supply information
Pharmacy stock checkers
Search for this medicine at major UK pharmacy chains. These links open the retailer's own website — results depend on their current online catalogue.
Supply & safety information
Official UK regulator monitoring and safety alerts
Pharmacy links redirect to the retailer's own search and do not represent real-time stock levels. Shortage and safety information sourced from MHRA drug safety updates (gov.uk, Crown Copyright under OGL v3.0).
Codes for healthcare professionals and prescribing systems
These codes are used by healthcare IT systems and prescribers to identify this medicine.
NHS UK identifiers
Browse tools
SNOMED CT and dm+d codes from NHS TRUD (Technology Reference data Update Distribution), licensed under the Open Government Licence v3.0. BNF code shown is the factual mapping value distributed by NHS Business Services Authority (NHSBSA) in the dm+d supplementary file under OGL v3.0; it is not affiliated with, nor licensed from, the publishers of the British National Formulary. ATC codes from the WHO Collaborating Centre for Drug Statistics Methodology (whocc.no).
Active and completed clinical studies from ClinicalTrials.gov
Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine (NLM), National Institutes of Health (NIH). Data accessed via ClinicalTrials.gov API v2. Trial information is provided for research purposes and does not constitute medical advice.
Academic studies and reviews for this medicine's active substance
Showing all 28 studies.
Reviews & meta-analyses: 3 · 2020–2025
Showing all 28 studies, sorted by most relevant.
Chen Z, Chen X, Li D, et al.
2025
- Adjuvants, Immunologic
- BCG Vaccine
- Urinary Bladder Neoplasms
BACKGROUND: Bacillus Calmette-Guerin (BCG) immunotherapy is the standard adjuvant treatment for high-risk, non-muscle invasive bladder cancer (NMIBC). However, BCG immunotherapy is commonly accompanied by significant lower urinary tract symptoms (LUTS) including symptoms such as urinary urgency, frequency, dysuria and pelvic pain. These symptoms can undermine treatment adherence and clinical outcomes. In this study, the treatments for preventing LUTS after BCG instillations were compared through a systemic review and network meta-analysis (NMA). METHODS: Eligible studies were obtained from the PubMed, Web of Science, Embase and Cochrane Library databases. We also searched the references of the included studies. Our protocol followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist. We performed NMA using Review Manager 5.3 and STATA MP 18.0. RESULT: The analysis included 6 studies with 556 participants. The results of the NMA revealed that celecoxib and prulifloxacin effectivelty reduce the incidence of LUTS including frequency, urgency and dysuria. Phenazopyridine showed the best performance in improving pelvic pain. CONCLUSION: The NMA indicated that medications such as celecoxib, prulifloxacin and phenazopyridine are effective in reducing the incidence of LUTS after BCG immunotherapy of bladder tumors.
Abstract licence: CC BY-NC-ND
Sasmith R. Menakuru, Vijaypal S. Dhillon, Mona Atta, et al.
Hematology Reports, 2023
Methemoglobinemia is an acute medical emergency that requires prompt correction. Physicians should have a high degree of suspicion of methemoglobinemia in cases that present with hypoxemia that does not resolve with supplemental oxygenation, and they should confirm this suspicion with a positive methemoglobin concentration on arterial blood gas. There are multiple medications that can induce methemoglobinemia, such as local anesthetics, antimalarials, and dapsone. Phenazopyridine is an azo dye used over-the-counter as a urinary analgesic for women with urinary tract infections, and it has also been implicated in causing methemoglobinemia. The preferred treatment of methemoglobinemia is methylene blue, but its use is contraindicated for patients with glucose-6-phosphatase deficiency or those who take serotonergic drugs. Alternative treatments include high-dose ascorbic acid, exchange transfusion therapy, and hyperbaric oxygenation. The authors report a case of a 39-year-old female who took phenazopyridine for 2 weeks to treat dysuria from a urinary tract infection and subsequently developed methemoglobinemia. The patient had contraindications for the use of methylene blue and was therefore treated with high-dose ascorbic acid. The authors hope that this interesting case promotes further research into the utilization of high-dose ascorbic acid for managing methemoglobinemia in patients who are unable to receive methylene blue.
Abstract licence: CC BY
Coyne BM, Ishaq SM, Thota A, et al.
2025
Methemoglobinemia is a condition caused by elevated levels of methemoglobin (MetHb) in the blood, a reduced form of hemoglobin that cannot properly bind to oxygen, interfering with delivery to tissues. If left untreated, this condition can be fatal. Phenazopyridine, an over-the-counter urinary tract analgesic, has been reported to cause methemoglobinemia in rare instances. In the present case, a 67-year-old patient demonstrated hypoxia and oral cyanosis in the setting of chronic phenazopyridine use and chronic obstructive pulmonary disease (COPD). A "chocolate-brown" coloration of his blood and an elevated MetHb level of 14.5% confirmed the diagnosis of methemoglobinemia. He was treated with methylene blue, ascorbic acid, bronchodilators, steroids, and supportive oxygen. This regimen led to a gradual improvement in the patient's clinical condition, including his hypoxia, cyanosis, and MetHb levels. This report illustrates a rare, unique case of phenazopyridine-induced methemoglobinemia and acute hypoxic respiratory failure in a patient with pre-existing COPD. In such patients, effective management requires a careful treatment approach directed at both methemoglobinemia and COPD.
Abstract licence: CC BY
At-har Najafi, M. Darbandi, Mahmoud Zarei
Journal of Molecular Liquids, 2025
Zhenliang Li, Zhongrui Zhang, Shaoying Yuan, et al.
Journal of Materials Science: Materials in Electronics, 2024
Peng Li, Dong Liang, Muhamad Humayun, et al.
Surfaces and Interfaces, 2025
García MC, Cuesta SA, Mora JR, et al.
2025
- Leucine-Rich Repeat Serine-Threonine Protein Kinase-2
- Antiparkinson Agents
- Machine Learning
Parkinson’s disease (PD) is a complex neurodegenerative disorder that affects multiple neurotransmitters, and its exact cause is still unknown. Developing new drugs for PD is a lengthy and expensive process, making it difficult to find new treatments. This study aims to create a detailed dataset to build strong predictive models with various machine learning algorithms. An ensemble modeling approach was employed to screen the DrugBank database, aiming to repurpose approved medications as potential treatments for Parkinson’s disease (PD). The dataset was constructed using pIC50 values of various compounds targeting the inhibition of leucine-rich repeat kinase 2 (LRRK2). The best ensemble model showed exceptional predictive performance, with five-fold cross-validation and external validation metrics exceeding 0.8 (Q2cv = 0.864 and Q2ext = 0.873). The DrugBank screening resulted in three promising drugs—triamterene, phenazopyridine, and CRA_1801—with predicted pIC50 values greater than 7, warranting further investigation as novel PD treatments. Molecular docking and molecular dynamics simulations were performed to provide a comprehensive understanding of the interactions between LRRK2 and the inhibitors in the data set and best molecules of the screening. Free energy of binding calculation along with hydrogen bond occupancy analysis and RMSD of the ligand in the pocket show CRA_1801 as the best candidate to be repurposed as LRRK2 inhibitor.
Abstract licence: CC BY-NC-ND
Alexander M Osborne, S. Rice, Kyle Seifert, et al.
Cureus, 2025
Methemoglobinemia is a rare but serious condition affecting the blood's ability to carry oxygen. Symptoms at presentation are often nonspecific. We describe the case of a 58-year-old female presenting with unexplained central cyanosis and severe hypoxia despite preserved respiratory effort and seemingly reassuring lab values. Further questioning revealed recent ingestion of a large quantity of phenazopyridine, an over-the-counter urinary analgesic known to cause oxidative stress. Co-oximetry confirmed significant elevation of methemoglobin levels. Methylene blue is well-regarded as the gold standard, and its use in treatment of this patient led to favorable clinical and laboratory improvement. Clinicians must maintain a high index of suspicion for dyshemoglobinemias in patients with unexplained cyanosis refractory to oxygen therapy, particularly when conventional metrics of oxygenation are inconsistent with the overall clinical picture.
Abstract licence: CC BY
Kapur A, Jericevic D, Wang R, et al.
2024
- Anesthetics, Local
- Lidocaine
- Administration, Intravesical
Santhiyagu Sahayaraj Rex Shanlee, Mariya Antony John Felix, Shen-Ming Chen, et al.
IEEE Sensors Journal, 2025
Sources: aggregated from Europe PMC (EMBL-EBI), OpenAlex, Crossref, PubMed and other open scholarly databases. Retracted articles are excluded. Study information is provided for research purposes and does not constitute medical advice.
Pharmacology and chemical data from DrugBank
Key facts
Drug status
Approved
Major interactions
196 found
Half-life
7.35 hours
Mechanism
The full mechanism of action of phenazopyridine is not fully elucidated[L7844],…
Food interactions
1 warning
Human targets
1 target
Data: DrugBank · CC BY-NC 4.0
Pharmacokinetics at a glance
Absorption
29.23 ng/mL
[A182159][L7850]
The mean Cmax is 65.00…
Half-life
7.35 hours
[A182174]…
Volume of distribution
[L7829]…
Metabolism
48.3%
[L7829]…
Elimination
65%
[L7829]
The…
Clearance
65%
Pharmacokinetic data: DrugBank · CC BY-NC 4.0
[L7826]
Phenazopyridine may be used in combination with antimicrobial therapy but is not used as an antimicrobial agent. It contributes to the relief of discomfort and pain before antimicrobial therapy begins to take effect. It is important to note that the duration of treatment with this drug should last a maximum of 2 days.
[L7826]
Phenazopyridine is available in many countries as an over the counter drug.
[A182147]
Known interactions with other medications. Always consult a healthcare professional.
Showing 50 of 764 interactions
[L7847]
Overdose information
Administering excess phenazopyridine above the daily recommended dose in those with healthy or impaired kidney function may increase the drug concentration and predispose the patient to toxicity. When a large overdose occurs, methemoglobinemia results.
[A182141][A182144]
To treat this condition, Methylene blue at 1 to 2 mg/kg/dose should be administered intravenously as a 1% solution as deemed necessary. Its administration is likely to cause a rapid reduction of the methemoglobinemia state and relieve the associated cyanosis.
Hemolytic anemia is also a risk when an overdose occurs, and “bite cells” may be observed in a blood smear after an overdose with phenazopyridine. Red blood cell G6PD deficiency may increase the risk of hemolysis, and even normal doses can lead to methemoglobinemia in patients with this condition. Nephrotoxicity, renal failure, and hepatic impairment may also occur in a case of overdose with this drug.
Administer symptomatic and supportive treatment as necessary.
[A182138][A182147][L7844]
A note on urine and skin discoloration and interference with test results
Yellowing of the skin or sclerae of the eyes may indicate that the accumulation of phenazopyridine has occurred. This may be a consequence of overdose, decreased renal function, taking the drug for over two days. Elderly patients may be at particular risk due to a decline in renal function, potentiating the risk of phenazopyridine accumulation. The drug should be discontinued if yellowing of the skin or sclerae is observed.[L7826] Hemolytic anemia is a risk of phenazopyridine, especially in cases of overdose. In addition to the above effects, this drug may impart an orange or red color of urine and feces, causing staining of clothing. Other body fluids may also be stained, and in patients wearing contact lenses, phenazopyridine may cause lens staining. Due to its orange-red color, this drug may interfere with laboratory requiring colorimetric, spectrophotometric or fluorometric methods of analysis.[L7826] In patients with G6PD enzyme deficiency, this drug poses a greater risk of hemolysis, even at normal doses and is not recommended.[L7826]
A note on carcinogenesis
Based on the results of in vivo studies in rats, this drug has been listed as a carcinogen in the USA since 1981. Rats given this drug were found to demonstrate increased rates of hepatocellular carcinoma and colorectal tumors.[L7871] Use this agent with caution and limit the administration of this drug when possible.
How the body processes this drug — absorption, distribution, metabolism, and elimination
[A182159][L7850]
The mean Cmax is 65.00 ± 29.23 ng/mL, the mean Tmax is 2.48 ± 0.50 h, and the mean AUC(0 – ∞)is 431.77 ± 87.82 ng.h/mL.
[A182171]
[A182174]
The half-life in man is not readily vailable in the literature.
[L7829]
A pharmacokinetic study in rats determined that phenazopyridine metabolites were present in high levels in the kidney and liver.
[A182174]
[L7829]
Hydroxylation is a pathway by which this drug is metabolized.
[A182180]
In humans, 5-hydroxyl PAP is the major metabolite (48.3% of the dose) and small amounts of other hydroxy metabolites are produced.
[A182171][L7865]
The metabolism of phenazopyridine produces aniline, which is likely associated with methemoglobinemia in some patients or in the case of an overdose. This dye accumulates in the skin, and yellow skin pigmentation has been observed when high doses of this drug have been taken.
[L7826]
Triaminopyridine is also a metabolite of phenazopyridine.
[L7865]
During a pharmacokinetic study, aniline contributed to approximately 6.9% of urinary metabolites. N acetyl-p-aminophenol (acetaminophen) contributes to about 18%, P-aminophenol (PAP) contributes 24%, and finally, DPP (unchanged phenazopyridine) contributes to about 41% of excreted urinary metabolites.
[A182159]
[L7829]
The pharmacokinetics of this drug have not been evaluated in depth in man. In a small group of healthy research volunteers, 90% of a daily 600 mg oral dose of phenazopyridine hydrochloride was found to be excreted within 1 day, with 41% as unchanged drug and 49% as phenazopyridine metabolites.
[L7826]
Another study in humans determined that 80.07 ± 4.54 percent of the dose was cleared in the urine within 48 hours of administration.
[A182156]
In rats, biliary excretion was high, with 40.7% of a dose excreted in 8 hours.
[A182174]
[L7826]
Proteins and enzymes this drug interacts with in the body
The influx of Na(+) ions provokes membrane depolarization, initiating the propagation of electrical signals throughout cells and tissues .
PMID:14672992
By regulating the excitability of neurons, ensures that they respond appropriately to synaptic inputs, maintaining the balance between excitation and inhibition in brain neural circuits (By similarity). Nav1.1 plays a role in controlling the excitability and action potential propagation from somatosensory neurons, thereby contributing to the sensory perception of mechanically-induced pain (By similarity)
ATC G04BX06
Chemical identifiers
CAS, UNII, InChI Key and database cross-references
Show
Chemical identifiers
CAS, UNII, InChI Key and database cross-references
Linked compound data from DrugBank Open Data (CC BY-NC 4.0)
Phenazopyridine
Additional database identifiers
Drugs Product Database (DPD)
20246
ChemSpider
4592
BindingDB
50420356
ZINC
ZINC000095483532
HUGO Gene Nomenclature Committee (HGNC)
HGNC:10585
GenAtlas
SCN1A
GeneCards
SCN1A
GenBank Gene Database
AF225985
GenBank Protein Database
12642270
Guide to Pharmacology
578
UniProt Accession
SCN1A_HUMAN
DrugBank citations
If you use DrugBank data in your research, please cite the following publications:
Show earlier publications
Structured knowledge from the free knowledge base
ATC classifications (Wikidata)
Linked open data from Wikidata (Q3114549), a free and open knowledge base operated by the Wikimedia Foundation. Data is available under the Creative Commons CC0 1.0 Public Domain Dedication. WHO INN from the World Health Organization.