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 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 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 is 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 any more?



  1. Great post….confirms much of what I’ve been trying to research! Happy to read that if bacteria is not binding to dmannose it likely will also have trouble holding on to the bladder wall. I asked my doctor to provide me a copy of the culture report in order to see exactly which kinds of bacteria are present. In the mean time I have Dr’s antibiotics in the fridge as a last resort. Dmannose continues to eliminate symptoms, day 8 or so…Taking it with less water and giving it time to bind before drinking more water seems to be working. blood in urine seems to be gone for the most part. It can all flare up so quickly again if I’m not consistent and watch my diet, sleep/stress etc. The explanations about bladder tissue damage and biofilms were also very enlightening. I hope to find a quality naturopath here in Toronto and work towards healing any damaged tissue. Thank you so much for your articles!!!


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