The Prostatitis Foundation

Quercetin and prostatitis
A compilation of newsgroup discussion


Note: Quercetin is a potent bioflavinoid found in many foods which has many health benefits. Dr. Daniel Shoskesof Cleveland Clinic Florida has published a research paper on Quercetin's benefits to prostatitis patients. See also Dr. Shoskes "go to" page.This web page consists of archived newsgroup postings, some from Dr. Shoskes, some from patients, most from 1999..

Two papers links the experimental prostate crug Elmiron, and its mode of action, to quercetin.

Note: a possible side-effect of too much quercetin has popped up.

There are at least two places to order Quercetin online:

Metabolic Response Modifiers --basic low-cost quercetin preparation. (Note: this link has been up and down...we're leaving it here even though you may have to phone in your order.)

Farr Laboratories --Produces Prosta-Q, a Quercetin preparation including other ingredients to aid absorbtion and effectiveness.

From: Daniel Shoskes MD

June, 1999

From a newsgroup posting...

The new "third generation" quercetin product is called ProstaQ and is made by Farr laboratories in California. We have samples that we have been using in our own patients for the past few weeks and have been thrilled at the results which have been superior so far to the first generation product currently sold by Metabolic Response Modifiers. In fact, we have switched patients who were on generic quercetin and doing well to ProstaQ with further improvements seen.

From: Daniel Shoskes MD
Subject: Quercetin study
Date: Sat, 15 May 2022 13:51:12 GMT
While I have to be very careful what information I can release prior to publication, I can report that the preliminary analysis shows a definite benefit of quercetin over placebo in our prospective, randomized, placebo controlled trial in men with chronic pelvic pain syndrome category III (culture negative). Of note, this should be the first published treatment study using the NIH chronic prostatitis symptom index, which we have found to be very responsive to changes in patient status.
Again, quercetin didn't help everyone, and in those it did help not everyone had complete resolution of symptoms. Furthermore, anyone with a positive EPS culture was excluded from the study (unless identical bacteria were seen in VB1 or the urethral swab). Therefore, since most doctors don't culture EPS, others may find a lower response rate in those patients who truly had positive cultures. Nevertheless, the only significant side effect in the study was a skin rash, which developed in a patient who turned out to be on placebo, so the risk/benefit ratio, at least in the short term, appears to be very favorable. As soon as the data is accepted either as an abstract for a meeting or "in press" in a journal, I will post the details of the results.
As I mentioned in a previous post, we have worked with a supplement company to produce a product for men with chronic pelvic pain syndrome that contains quercetin, along with other agents that improve the absorption of quercetin and enhance the anti-inflammatory and anti-oxidant effects. I am using this product now exclusively for my patients, and it should be available for retail sale very shortly. [Note: see above] I will post a phone number as soon as it is available, or email me at and I will reply with the information as soon as I get it. I know that many in the UK and Europe have had trouble obtaining quercetin from our previous supplier: our current supplier has an extensive distribution network in Europe, so it shouldn't be a problem much longer.

May 12, 2022
What I have learned from using quercetin in many patients with different symptoms and forms of chronic prostatitis/chronic pelvic pain syndrome is that the use of pure quercetin, while effective in many patients, is a start, but can be improved upon. I think it is particularly important to address absorption issues, because quercetin has variable absorption when taken alone. We are currently working with a supplement manufacturer to produce a capsule for us which combines a known potent dose of quercetin with agents that can improve quercetin absorption as well as agents that can work synergistically with quercetin to reduce oxidant stress in the prostate. Oxidant stress has been implicated in chronic prostatitis, male infertility and prostate cancer.
I should have a supply of this formulation within several days to try in our own clinics. I hope soon after to be able to provide a phone number and address for patients who cannot visit our clinics who wish to purchase the product. I will also post this info on our IMU mailing list, which can be joined at or you can email me at and I will reply with the information as soon as I have it.
Let me emphasize that this is not a panacea for every patient with chronic pelvic pain syndrome. It is unlikely to help if you have active infection in the prostate or symptoms arising only from pelvic muscle spasm. Furthermore, as I have mentioned many times, please do not combine this with quinolone antibiotics (eg Trovan, Cipro, Levaquin, Noroxin, Floxin) since it may interfere with the action of this class of antibiotics. Nevertheless, I am very optimistic that this new formulation will be superior to "generic" quercetin, particularly for patients who had mild and/or variable response to quercetin alone or who required double or triple the standard dose to get relief.
Daniel Shoskes MD

From: cp
Subject: Re: Quercetin update
Date: Sat, 17 Oct 2021
Dr. Shoskes,
Thank you for all your interest and contribution to this group. I appreciate the replies you've given to my questions and also for your research work. I hope your study on Quercetin will support my experience and confirm that it is responsible for my improvement.
I stopped antibiotics 2 months ago, and I have been taking GNC vitamin C plus Quercetin for the last 2 months as well as GNC Ultra Saw Palmetto complex since I stopped antibiotics. I have improved a lot, but not totally. I also found the antibiotics I was on Trovan 5 weeks, and Doxycycline 12 weeks both were actually causing worsening of my symptoms following taking a dosage. I found about 2 hours after taking either antibiotic I had extreme urgency and frequency for a few hours. I kept attributing it to the prostatitis, but tested it last week again by taking 1 Doxyxycline. Sure enough I had the same result 2 hours after I took it. Since being on the GNC products, and (incidentally tried the Quercetin because of your previous research), the other urinary symptoms are reduced, but not gone. I don't know how potent the Quercetin is in the GNC product, but it was all I could find locally, so I hope it is good quality.
If you have any idea why the antibiotics are causing this reaction of urgency and frequency that lasts for a few hours, or if it reveals something that may be the answer to my problems, your comment would be greatly appreciated. I still have some perineal discomfort and sensitivity of glans, and my urethra seems a little irritated at times. I never tested positive to cultures which were not very thoroughly done however, but am afraid I may have some type of remaining infection and cannot take the antibiotics without a major reaction of urgency and frequency.
In the mean time I continue the GNC products religiously and believe stopping the antibiotics and taking the two GNC items have been responsible for my improving greatly. Now if only I was totally better I would really be a firm believer. Perhaps in a few months I will continue to improve and be able to make that claim, and perhaps you will uncover the answer in your study. If I was closer to you I would not hesitate to seek treatment there, but unfortunately am in Florida and haven't found anyone focused or dedicated to this disease.
Thanks again,

From: (Daniel Shoskes)
Subject: Quercetin update
Date: Thu, 15 Oct 2021
We have been using Quercetin for the past year as a therapy for nonbacterial prostatitis and prostatodynia with promising results. The major problem has been that as a nutritional supplement, it is not FDA regulated and not subject to third party quality control. Consequently, for patients that Quercetin has not helped, we have not known whether a suitable amount of Quercetin was actually in the tablets the patient bought. Indeed, some patients had no success with one brand and then excellent success with another.
As a result, we have been working with a nutritional supplement manufacturer ( Metabolic Response Modifiers in Newport Beach CA) to provide us with a capsule containing Quercetin of documented purity and bioavailability. We finally now have a supply which we are providing to our patients to try. We shortly will also be provided with placebos that look the same so we can carry out a double blinded placebo controlled trial to finally prove or disprove that Quercetin is effective in this disorder.
Daniel Shoskes MD
Institute for Male Urology

Subject: Quercetin paper
Date: Fri, 14 Aug 2021
For anyone interested in the more "basic science" side of bioflavonoids such as Quercetin, there is an article I just published in the current issue of Transplantation entitled: "Effect of bioflavonoids Quercetin and curcumin on ischemi renal injury". The article has nothing to do with prostatitis, but does discuss mechanisms of action of Quercetin at the cellular and molecular level.
The reference is Transplantation 66(2):147-152 (it will probably be a few weeks before it is abstracted in medline).
Daniel Shoskes MD
Institute for Male Urology

From: dshoskes
Subject: Quercetin capsules
Date: Tue, 20 Oct 2021
Many people have emailed me about the Quercetin capsules I am currently using in my research that have been made with documented purity by a company for us. The company does sell to the public and can be reached at the address below. I should emphasize that this is not an endorsement of the product: we have just started our study on this purified form and there is no guarantee that it will be better than store bought. I believe they sell 60 500mg capsules (1 month supply) for about $11.
Metabolic Response Modifiers (link takes you to company website)
2633 W. Coast Hwy - Suite B
Newport Beach, CA 92663

If you call them, please say it is for prostatitis and you were referred by me so that companies have some idea of the demand for prostatitis products of high quality. I want to emphasize that they supply me with capsules for our research but I do not receive monetary compensation from them.
Daniel Shoskes MD
Institute for Male Urology

Subject: Quercetin
From: Electric87
Date: Sun, 7 Jun 2022
Does anyone know if there are any dangerous side effects when taking the anti-inflammatory herb Quercetin with antibiotics? Dr. Shoskes? Anyone? Brian

Subject: Re: Quercetin
From: Daniel Shoskes
Date: Mon, 8 Jun 2022
Based on "test tube" data, Quercetin may make the quinolone antibiotics (cipro, floxin, trovan etc) less effective. I never give Quercetin at the same time as antibiotics.
Daniel Shoskes
Institute for Male Urology

Subject: For Dr. Shoskes re: Quercetin
From: gmiller
Your web page notes that Quercetin should not be given in combination with certain antibiotics. Which antibiotics are those and why? I ask because I have had recommended to me a nutritional supplement that contains many, many things, among them Quercetin.

Date: Sun, 9 Aug 2021
From: dshoskes
Subject: Anti-fungal properties of Quercetin
I began using Quercetin for chronic pelvic pain syndromes with some success for the past 2 years for it's anti-inflammatory properties. I knew that it had very mild antimicrobial effects, binding to the DNA-gyrase site of E. coli (the same site that quinolone antibiotics attack), but now there appears the following evidence for an anti-fungal role as well.
Daniel Shoskes MD
Institute for Male Urology

Microbios 1998;93(374):43-54
Comparative antibacterial and antifungal effects of some phenolic compounds.
Aziz NH, Farag SE, Mousa LA, Abo-Zaid MA
National Centre for Radiation Research and Technology, Nasr City, Cairo, Egypt.
The antimicrobial potential of eight phenolic compounds isolated from olive cake was tested against the growth of Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Aspergillus flavus and Aspergillus parasiticus. The phenolic compounds included p-hydroxy benzoic, vanillic, caffeic, protocatechuic, syringic, and p-coumaric acids, oleuropein and Quercetin. Caffeic and protocatechuic acids (0.3 mg/ml) inhibited the growth of E. coli and K. pneumoniae. The same compounds apart from syringic acid (0.5 mg/ml) completely inhibited the growth of B. cereus. Oleuropein, and p-hydroxy benzoic, vanillic and p-coumaric acids (0.4 mg/ml) completely inhibited the growth of E. coli, K. pneumoniae and B. cereus. Vanillic and caffeic acids (0.2 mg/ml) completely inhibited the growth and aflatoxin production by both A. flavus and A. parasiticus, whereas the complete inhibition of the moulds was attained with 0.3 mg/ml p-hydroxy benzoic, protocatechuic, syringic, and p- coumaric acids and Quercetin.

Date: Sat, 8 Aug 2021
From: cp
Subject: Message for Dr. Shoskes, re:Quercetin
After reading your test case on Quercetin a few weeks ago, I began a regimen of a GNC compound consisting of vitamin C 600mg, and Quercetin 200mg tablets twice per day.
I was wondering if the dosage per day which equals 1200mg ascorbic acid and 400mg Quercetin would be considered an adequate amount to have any affect. In your study I believe you administered 1gm of Quercetin per day. Is 400 mg Quercetin enough to try?
Since starting the compound, I have begun to feel improvement, but cannot rule out the possibility of coincidence at this point, as I have felt better at other times for no apparent reason, and then symptoms have returned with a vengeance.
I will post my progress on the group, but at this point can't make a fair evaluation. I also tried Nystatin oral for a few weeks prior to the C/Quercetin complex, with no positive effect.
Thanks as always for your interest, focus, and dedication to helping those on the group.
I'm sure I speak for most everyone that you are greatly appreciated.


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