Treatment of interstitial cystitis with a quercetin supplement

Interstitial cystitis (IC) is a disorder of unknown etiology with few effective therapies. Oral bioflavonoid therapy utilizing quercetin recently proved to be clinically effective in men with chronic pelvic pain syndrome, a disorder with similarities to IC. We therefore tested in an open-label trial a quercetin-based supplement in patients with clinically proven IC.

Twenty-two patients (5 men and 17 women; average age 53.1 years) with classically documented IC received one capsule of Cysta-Q complex (equivalent to 500 mg of quercetin) twice a day for 4 weeks. Symptoms were assessed before and after therapy by the IC problem and symptom indices as well as by global assessment of pain (range 0-10).

Two patients did not complete the study. In the remaining 20 patients, improvement was seen in all three parameters tested. After 4 weeks of treatment, the mean (+/- SEM) problem index improved from 11.3 +/- 0.6 to 5.1 +/- 0.7 (p = .000001), the mean symptom index improved from 11.9 +/- 0.9 to 4.5 +/- 0.5 (p = .000001), and the mean global assessment score improved from 8.2 +/- 0.4 to 3.5 +/- 0.4 (p = .000001). None of the patients experienced any negative side effects, and all but one patient had at least some improvement in every outcome measure.

Oral therapy with the quercetin supplement Cysta-Q was well tolerated and provided significant symptomatic improvement in patients with IC. Larger, randomized, placebo-controlled trials appear warranted based on these preliminary open-label results.