Evidence Trace, complete trial record

In plain terms

In plain terms: RIMSO-50 (Dimethyl Sulfoxide Bladder Instillation) has some human trial evidence supporting it, but the evidence is not yet strong enough for EBL to call it established. It is worth knowing about and worth discussing with your clinician.

RIMSO-50 (Dimethyl Sulfoxide Bladder Instillation)

B Supported: a good trial, backed by more

Category Longevity Rx

Class Bladder instillation · Prescription only

Evidence Randomized controlled trials + meta-analysis

Reviewed September 2026

PMIDs 3288775 · 33580603 · 40205912 · 28124536 · 36747494

The endpoint this grade is based on: self_report, Symptom relief in interstitial cystitis, the only use the FDA has approved for DMSO, given by a clinician through a catheter into the bladder. Two independent placebo-controlled trials agree.

The evidence as the record states it

Evidence record

PMID 3288775 PMID 33580603 PMID 40205912 PMID 28124536 PMID 36747494

Perez-Marrero et al. (Journal of Urology, 1988; PMID 3288775): randomized crossover trial, 33 patients with biopsies suggestive of interstitial cystitis, 50% DMSO versus saline; 53% markedly improved on DMSO versus 18% on saline, and 93% versus 35% on objective improvement. Yoshimura et al. (International Journal of Urology, 2021; PMID 33580603): multicenter, randomized, double-blind, placebo-controlled trial in Japanese patients with bladder-centric interstitial cystitis; the symptom index fell 5.2 points on DMSO and 3.4 on placebo at 12 weeks. Li et al. (Neurourology and Urodynamics, 2025; PMID 40205912): meta-analysis of 5 randomized trials and 9 single-arm or cohort studies, 554 patients; adverse events in 37.6%, mostly mild. Tutolo et al. (International Brazilian Journal of Urology, 2017; PMID 28124536): DMSO versus chondroitin sulfate 2%, chondroitin better, high DMSO withdrawal. Moss et al. (Neurourology and Urodynamics, 2023; PMID 36747494): DMSO with triamcinolone versus bupivacaine, triamcinolone and heparin in newly diagnosed women.

PMID 3288775 PMID 33580603 PMID 40205912 PMID 28124536 PMID 36747494

Why Grade B and not Grade A

Grade B reflects moderate human evidence -- typically a single strong trial, multiple smaller trials, or surrogate endpoint data without hard clinical outcome replication. To reach Grade A, RIMSO-50 (Dimethyl Sulfoxide Bladder Instillation) would require at least one additional independent randomized trial demonstrating a hard clinical endpoint or objectively measured functional outcome in a comparable population.

What this grade covers and what it does not

Grade B on two placebo-controlled trials run by independent groups in different countries. In the United States, 33 patients with interstitial cystitis received 50% DMSO or saline into the bladder in a randomized crossover trial; 53% were markedly improved on DMSO against 18% on saline (Perez-Marrero et al., 1988; PMID 3288775). In Japan, a multicenter double-blind trial of the same 50% solution found a larger fall in the O'Leary-Sant symptom index than placebo at 12 weeks, a difference of 1.8 points (Yoshimura et al., 2021; PMID 33580603). A 2025 meta-analysis of 5 randomized trials and 9 cohort studies in 554 patients reports symptom and pain scores falling from baseline (PMID 40205912). WHY B AND NOT A: The endpoints are symptom and pain scores the patient reports, and a self-reported endpoint caps a record at B however well the trials agree. The Japanese trial was funded by the manufacturer of its product. WHAT THIS GRADE DOES NOT COVER: DMSO on the skin or by mouth, which are graded on the DMSO record. Head-to-head, a trial against intravesical chondroitin sulfate found DMSO worse, with 57% of the DMSO group withdrawing for pain, odor or lack of effect (PMID 28124536), and a trial against a bupivacaine, triamcinolone and heparin cocktail found DMSO with triamcinolone better on pain and nocturia and similar on overall symptoms (PMID 36747494).

What would move this grade

An independent randomized trial demonstrating a hard clinical endpoint -- mortality, major adverse event, or objectively confirmed functional improvement -- in an adequately powered sample, with results independently replicated, would support Grade A.

How this was studied

Form: RIMSO-50, 50% dimethyl sulfoxide solution, instilled into the bladder by catheter, versus saline or placebo · Dose: 50 mL of 50% DMSO held in the bladder for about 15 minutes; every 2 weeks for two courses of four instillations (1988 trial) · Population: 33 patients with biopsies suggestive of interstitial cystitis, 30 women and 3 men, mean age 48 (United States); Japanese adults with bladder-centric interstitial cystitis/bladder pain syndrome (Japan) · Duration: Two 4-instillation courses in the crossover trial; 12 weeks in the Japanese trial · What is sold differs: A prescription product given in a clinic by a urologist or gynecologist. It is not the DMSO sold as a liquid or gel, and the trials say nothing about those.

How to track whether this is working Prescription only; given and managed by a urologist or gynecologist. The trials measured the O'Leary-Sant symptom and problem indexes, pain scores and voiding diaries.