OpenClaim

Pentosan Side Effects

The most commonly reported side effects of pentosan include maculopathy, off label use, and retinal pigmentation, based on 6,955 FDA adverse event reports from 2004 to 2025. 4.3% of reports found the drug to be ineffective.

Pentosan side effects

Percentages show how often each reaction appears relative to total reports for pentosan.

1
Maculopathy20.0%1,393
2
Off Label Use20.0%1,392
3
Retinal Pigmentation8.7%607
4
Dry Age-related Macular Degeneration8.0%559
5
Pigmentary Maculopathy6.6%456
6
Drug Ineffective4.3%302
7
Product Use Issue3.9%272
8
Pain3.8%267
9
Nausea3.2%220
10
Macular Degeneration3.0%209
11
Headache2.8%194
12
Cystitis Interstitial2.7%186
13
Age-related Macular Degeneration2.6%184
14
Diarrhoea2.6%178
15
Alopecia2.5%172

These are voluntary reports and do not establish that pentosan caused these reactions.

Report severity

70.2%Serious4,879 reports
9.6%Hospitalizations668 reports
1.8%Fatal122 reports

Seriousness is determined by the reporter, not by OpenClaim.

Pentosan drug interactions

Other drugs that appear in adverse event reports alongside pentosan. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Adalimumab2.9%203
2
Sodium-oxybate2.8%195
3
Acetaminophen1.0%70
4
Vedolizumab0.9%66
5
Pregabalin0.8%57
6
Etanercept0.8%54
7
Gabapentin0.8%54
8
Lansoprazole0.6%45
9
Fentanyl0.6%45
10
Esomeprazole0.6%45
11
Ondansetron0.6%43
12
Duloxetine-hydrochloride0.6%40
13
Ethinyl-estradiol0.6%39
14
Leuprolide0.6%39
15
Heparin0.5%33

Taken alongside

1
Levothyroxine-sodium11.5%802
2
Acetaminophen9.4%653
3
Gabapentin8.6%595
4
Omeprazole8.2%571
5
Ergocalciferol7.9%548
6
Amitriptyline-hydrochloride7.0%490
7
Hydroxyzine6.4%447
8
Albuterol5.9%410
9
Fluticasone5.5%386
10
Estradiol5.4%377
11
Pantoprazole-sodium5.4%373
12
Atorvastatin-calcium5.3%368
13
Tramadol-hydrochloride5.2%363
14
Montelukast-sodium5.2%359
15
Duloxetine-hydrochloride5.1%352

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports pentosan side effects

85.7% of pentosan adverse event reports involve female patients and 9.2% involve male patients. The largest age group is adult at 73%. These figures reflect who reports side effects, not underlying risk.

Sex

Female85.7%
Male9.2%
Unknown5.1%

Age group

< 20.1%
2–110.2%
12–170.4%
18–6473.4%
65+25.9%

What is pentosan used for

Conditions and purposes for which patients were taking pentosan when the adverse event was reported.

Abdominal DistensionAbdominal PainAccidental Exposure To ProductAdnexa Uteri PainAnticoagulant TherapyAbdominal Pain UpperAnalgesic TherapyAngiosarcomaAnticoagulant TherapyAntidepressant TherapyBack PainBenign Prostatic HyperplasiaBladder CancerBladder CystBladder Discomfort

Showing 15 of 179 indications

Pentosan brand names and reporting trend

Pentosan is sold under the brand name Elmiron.

Brand names

Elmiron338

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking pentosan with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.