why d-mannose doesn't work

D-Mannose doesn’t work, am I resistant to D-Mannose?

Is it possible that all over sudden D-Mannose doesn’t work for you? Especially if it seemed to work before?

I’ve seen several D-Mannose fans mentioning that the powder stopped working for them or they need to consume much bigger doses to make it work, which begs the questions: can you become resistant to D-Mannose?

To answer this, we need to review how D-Mannose works and how resistance is developed.

#1 Here is how D-Mannose works (when it does) under a microscope

In case if you are not familiar with a general concept of how E. coli interacts with D-Mannose, this is a primer for you: What’s D-Mannose and how does it work. This post will explain that E. coli could attach itself to D-Mannose and therefore is washed away from your bladder with urine.

But how exactly E. coli attaches itself  D-Mannose? Let’s zoom in.
E. coli bacteria can express so-called “pili” (they are like tiny hairs sticking out of bacterias’ bodies). E. coli can potentially grow up to 16 different types of those hair-like appendages. However, there is only one type that “grabs on” to mannose (either the one on your bladder wall or D-Mannose in your urine).

Unfortunately, scientists do not know what makes E. coli to grow one type of pili versus another.

Fortunately, most of the harmful E. coli types that cause repeated UTIs grows that particular pili that we need in order for D-Mannose to work. But again, nobody knows why. As you can see, there is already plenty of room to speculate why D-Mannose doesn’t work for you but works for somebody else.

#2 Here is how bacterial resistance happens

If you have developed an acute bladder infection, it means that pathogenic bacteria are present in your bladder.

Now, when you drink an antibiotic, let’s imagine it will kill 99% of bad bacteria. However, 1% that remained alive due to genetic mutation had some properties that allowed those bacteria to survive.

Next, the survivors will pass on their genes and reproduce to create more bacteria with the advantageous (to them) properties. Therefore, the next generation becomes resistant to the antibiotic that has been used on their parents (if the parents survived, of course). It is basic natural selection at play: we kill “weak” ones and the “strongest” survive.

#3 Possible reasons why D-Mannose doesn’t work

First of all, D-Mannose does not kill bacteria at all, which is a good thing. So it is theoretically impossible to develop resistance to D-Mannose.

Imagine, you have a bunch of harmful bacteria stuck to your bladder walls, you throw in D-Mannose, they stuck to the sugar instead, and are washed out while you are peeing.


a) D-Mannose forms a pretty weak bond with E. coli, so it could happen that some bacteria “unstick” from the sugar and remain in the bladder to reproduce.

b) Theoretically, it is possible that some of your E. coli might not express the pili that are needed for them to stick to mannose. However, in that case, they, perhaps, are not going to be able to stick to your bladder walls either.

But other factors could complicate the situation and make it harder to eliminate harmful bacteria, which would seem to you as though D-Mannose doesn’t work anymore.

Here are options why:

  • Every UTI instance damages your bladder lining. Damaged bladder lining provides more “hiding” space for bacteria and it becomes harder and harder to completely get rid of it.
  • Bacteria can form biofilms, that make the bacteria “stronger” and harder to eliminate.
  • There could be multiple pathogenic bacteria types present, and only E. coli reacts to D-Mannose.
  • You might not even have an infection and that’s your bladder “phantom pains” due to repeated lining damage. In that case, D-Mannose obviously won’t work
  • Some say D-Mannose irritated their bladder. Perhaps instead of “resistance”, you are becoming allergic to D-Mannose and this is bladder irritation, not UTI symptoms?

Back to you: what are your thoughts? Does the magic powder work for you or not anymore?


27 thoughts on “D-Mannose doesn’t work, am I resistant to D-Mannose?”

  1. Nadine Reymen

    Dear Anastasia, my UTI started June 18 ( this one … previous one only three months ago … average 2 yearly …) , sex related althoug I’ve been taking D mannose for 2 years now and increase amount when active etc etc. So I was convinced to beat the UTI with DM ( pure DM from Waterfall). Started taking very high doses up-to 35 Gr per 24 hrs … :-0 in meantime culture was taken and concluded E coli. So I persisted with the D mannose. Gave very little relief but not sufficient so after 2 weeks new culture and E coli was still present. Spent almost 200USD in 2 weeks on DM … Took it as instructed, drank lost etc etc … so I just need to conclude my E Coli has different pili as all other women were it does work as a miracle? I’m in tears since I ‘m allergie to nitrofurantoine, fosfomycine doesnt work for me so I’m ending up with Cipro every time. Desperate :-/

  2. thank you so much for this informative post. i’ve been dealing with recurrent uti since the first time i had sex and if i do nothing to prevent uti from occurring, i get it almost 2 times a month. d mannose has been helping but ut doesn’t prevent my uti entirely. taking d mannose every single time after sex, i sometimes don’t get uti at all for a few months but then i might get uti every week for a few month even tho the way i take d mannose stayed the same. i wonder if it is more effective to take it before or after sex and how long it stays effective in our body after taking it? it would be of great help if you know about it .

    1. Hi Lyc, unfortunately, I don’t think I know the answer. But if to brainstorm, what if you look at your menstrual calendar and see if the times that you get a UTI fall on the days right before or after periods and the times when you don’t are closer to the mid-cycle. If so, this could provide a clue of the role your vaginal flora plays in the recurrence. Since bacteria during sex are moved around they could be lifted up directly toward your urethra or just get closer to your vagina. In the last case, we can speculate that it’ll take them couple more days to ascend further up. Have you considered taking D-Mannose for longer periods, for example, a preventive dose daily for a month? And perhaps double it down on the days after sex? Not a medical advice, just girl’s talk. Best to check with a naturopath for a comprehensive approach to prevention.

  3. Anastasia,
    This article is very informative, thank you! I just wanted to make sure I understand it in terms of my situation. I dealt with reacurring uti’s from sex for about 4 years, about once every 3 to 4 weeks. When I started taking d mannose after sex it was a miracle. In the last year and a half I’ve only had 1 infection and I think it was because I waited too long after sex to take the d mannose. When I did get an infection that one time I tried taking d mannose every 2 hours to treat the infection. It didn’t work and I had to take antibiotics. But the d mannose has continued to work as a preventative since that one infection a year ago. Today, I forgot to take it after sex for a couple hours, similarly to the last infection, and fear that I’ll get an infection. I’m considering taking the d mannose throughout the whole day to prevent the infection but I don’t want risk creating an immunity to it, being that it didn’t work to treat an infection last time, but only works to prevent one. I see that theoretically I shouldn’t worry. Do you agree? It should I just let the infection develop to about risk of letting the ecoli learn how to about attaching itself to the d mannose? Thanks!

    1. Sorry for the typos in that last sentence! Should I just let the infection develop to avoid the risk of letting the ecoli learn how to avoid attaching itself to the d mannose?

      1. Hi Lindsey 🙂
        I think you shouldn’t worry and go ahead take it. Resistance is not built because bacteria learn how to react, but mostly because there are already bacteria that are not affected by whatever measure is tried on them, and then they are the only survivors who keep multiplying. Hope this makes sense! D-Mannose, unlike antibiotics, does not kill bacteria. There are multiple types of bacteria causing UTI, even multiple types of E. coli. But it’s believed that the pathogenic type of E.coli adheres to the bladder’s mannose with their hands called “pili”. So in the essence, if E. coli are already pathogenic (could cause a UTI) then they also should attach to D-Mannose. Did your physician office do a urine culture last time? Perhaps, this was a combo of pathogenic bacteria. I’d suggest adding some other antibacterials (supplements, herbs) to your routine and since your UTIs are “caused” by sex, also look at you vaginal health. You are welcome to join our FB group if you’d like to chat more!

  4. Hi
    I am dealing with proteus mirabilis. Most implements are designed to fight that. I have been on a broad spectrum antibiotic that didn’t knock it out even though it was sensitive to it. During the treatments I never felt healing. Here I am 6 days later burning. Urinalysis shows white blood cells but no infection. Since urinalysis, the symptoms are worse. I read a study that was done in 2012 where scientists tested cranberry powder on Ecoli and proteus mirabilis because they are both gram negative. They said it worked to disable them from swarming because it hindered the flagella. My question is do you think that d mannose could possibly help in my situation? Do you know of any supplements that could possibly hinder proteus mirabilis ? I do not want to go on antibiotics again.

    1. Excuse my typos. I’m very tired. I meant most supplements aren’t geared towards hindering that particular strain.

    2. Hi Trenika,
      Sorry, sounds exhausting!
      However, I’m confused why they prescribe you antibiotics as per your comment “Urinalysis shows white blood cells but no infection”? You mean they did a culture test and it shows no bacterial growth? Also, have you had cystoscopy?
      If no culture in urine, did you try asking your doctor for NSAIDs? Especially if the only symptom is burning I highly recommend looking for a second opinion rather than sticking with the doc who prescribes antibiotics when no active infection is detected. I’m not a doctor but if I were you I’d ask the physician if I could take Ibuprofen, changed my diet and focus on healing the bladder. I’d also see either a naturopathic or a homeopathic doctor.

      If you keep still taking antibiotics right now, see this post about biofilms . Also, this one and this one.

      Best of luck! You can also join our FB group that I just started to stay in touch.

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