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Thread: Is methenamine long-term safe ?

  1. #11

    methenamine continued

    Another post on this forum, located here, cites an occupational hazard study that failed to find a link between bladder cancer and formaldehyde as proof that formaldehyde does not cause bladder cancer. However, therapeutic use of methenamine is likely to result in a far higher concentration of formaldehyde in the bladder than incidental occupational exposure to formaldehyde vapor. So until safey can be affirmatively established long term use should be avoided.

  2. #12
    Quote Originally Posted by smokey View Post
    If "Methenamine" is also known as "Mandelamine" then I'd say it's safe for long term usage. I've been taking 1G. twice a day of Mandelamine for 31 years without any side effects.....well it has left me with an extraordinarily long penis. Just kidding, I have been taking it for 31 years. It's fine as far as I know. Actually I'm running a little low on my supply. I thought they were going to stop manufacturing Methanamine/Mandelamine?
    I had to start getting methenamine from Canada, it's getting hard to find in the US unless it's the hippurate form, which messes w/ my stool consistency. I've been using meth (enamine) ;-) for over a year now, works good.

  3. #13
    I had a bad reaction to the formaldehde from this drug,made me dizy and short of breathe ect.My doctor does not like this drug at all and insists he won't prescribe it anymore,but try it and if it works for you thats better than constant infections.........

  4. #14
    It has vastly improved my life . I swear by it. I'm very concerned though, just thinking of what turnining my urine into formaldahyde(?) is doing to me internally. Then again, the other drugs are probably ruining something else. Without it, the uti's would be killing me though...

  5. #15

    Does Methenamine Cause Bladder Cancer?

    Does Methenamine Cause Bladder Cancer?

    Methenamine is readily available over the counter for treatment of UTI (Cystex, Hiprex). NIH lists over 20 medications containing this substance. According to a 2008 Risk Assessment by the European Commission, “Methenamine has been used for years … for long-term prophylaxis of urinary tract infections in patients who are at risk for bacterial reinfections.” A quick search discloses dozens of studies of methenamine for UTI, including studies of long term use in populations with recurring UTI. So it is likely that methenamine is in long term use by a significant number of persons.

    Methenamine is converted to formaldehyde in an acid urinary environment, which consequently kills bacteria. Formaldehyde is a well-known human carcinogen. Of the various organs in the urinary tract, the bladder will suffer the greatest exposure due to the storage of urine. Are such exposures safe? The above mentioned risk assessment appears to have undertaken a thorough review of the literature.

    The longest of the studies cited lasted 104 weeks (Della Porta et al., 1968). Rats were supplied with 1% methenamine in drinking water over this period. The study abstract states: “No evidence of carcinogenic activity could be found in any of the test groups.” A careful reading of the study itself tells a different story. The authors simply compared the total numbers of tumors in the test and control groups without regard to where the tumors occurred. Only the bladder is subject to long term continuous exposure to formaldehyde as a result of methenamine use. Counting tumors elsewhere masked this data: 3 of the 48 male test rats developed bladder cancer. None of the female or control rats did. Among humans the incidence of bladder cancer in males is also more than 3 times that of females. If the bladder tumors were occurring at random, the probability of all three coincidentally showing up in the male test animal quadrant is .016. So this study indicates that methenamine does cause bladder cancer in male rats.

    Nonetheless, based on an uncritical reading of the study the risk assessment concludes: “In long-term oral studies in experimental animals there was no evidence of carcinogenic activity in rats and mice following high dosage ... methenamine after long-term treatment.” This conclusion was not justified.

    A couple of other studies are worthy of attention. Siemiatycki, et al. (1994) reviewed 484 cases of bladder cancer to look for possible associations with environmental exposure to carcinogens. They ruled out any association between bladder cancer and exposure to formaldehyde. However, according to Pandey et al.(2000), formaldehyde absorbed into the bloodstream is converted to formic acid within 90 seconds. Formic acid is then excreted through the kidney as sodium salt or is further oxidized to carbon dioxide and water. So formaldehyde will not enter the bladder as a result of environmental exposure. Therefore, such environmental studies do not bear upon the safety of methenamine.

    Wang, et al. (2007) showed that in vitro, formaldehyde exposure produced DNA damage in urinary bladder transitional epithelium of rats. Repair of the induced DNA damage then occurred within 4 hours. Unfortunately, in the case of long term use of methenamine, the exposure to formaldehyde will be almost continuous, creating the likelihood of overwhelming the repair mechanism.

    Based on the foregoing there is good reason to be concerned that formaldehyde in the bladder, as a result of methenamine use, does indeed cause cancer.

    The author of this note had taken methenamine continuously from 2007 though 2010, at a dosage of .4g, TID. The purpose was to suppress UTIs arising from bacterial shedding from a prostate afflicted with bacterial prostatitis. At the outset of 2011, bladder cancer was found via cystoscopy. There were no other risk factors for this condition: no family history of bladder cancer, never a smoker, a non drinker, a mostly organic and vegetarian diet, work in electronics and computing, and living in a remote unpolluted area. Perhaps others can be spared a similar fate.


    Della Porta, G., Colnaghi, M.I., Parmiani, G. (1968): Non-carcinogenicity of Methenamine in Mice and Rats. Fd. Cosmet. Toxicol. 6, 707-715

    European Commission, Joint Research Centre (JRC), Institute for Health and Consumer Protection (IHCP) : RISK ASSESSMENT, Methenamine, CAS-No.: 100-97-0, EINECS-No.: 202-905-8, 27.05.2008, FINAL APPROVED VERSION

    NIH list of medications containing methenamine:

    Pandey, C.K., Agarwal, A., Baronia, A., Singh, N. (2000) Toxicity of ingested formalin and its management. Human Exp. Toxicol. 19, 360-366

    Siemiatycki, J., R. Dewar, L. Nadon and M. Gerin. 1994. Occupational risk factors for bladder cancer: results from a case-control study in Montreal, Quebec, Canada. Am J Epidemiol 140(12): 1061-80.

    Wang A, Robertson JL, Holladay SD, Tennant AH, Lengi AJ, Ahmed SA, Huckle WR and Kligerman AD (2007). Measurement of DNA damage in rat urinary bladder transitional cells: improved selective harvest of transitional cells and detailed Comet assay protocols. Mutat Res. 634: 51-9.

  6. #16
    Wow this is scary! Methanamine mandalate causes bladder cancer!

    Me Before Methanamine mandalate:
    Cloudy urine always, pain in bladder, feverish uti outbreaks every two-three months that are only treated with antibiotics

    After methanamine Mandalate:
    Urine clear, no pain, bladder holds larger volumes, I void larger quantities, No signs of uti's at all.

    I have a feeling uti's will kill me. But now methanamine will cause me bladder cancer. Which is the less painful way to die?
    Last edited by 24thchromosone; 07-17-2012 at 09:20 PM.

  7. #17
    I should note my circumstances and my belief set of it's success.

    t5 complete

    I typically void at 400ml of urine all the way down to 180ml which my neurological bladder can't seem to relax enough to release it all. So to help cleanse the bladder once a day i use a catheter to get it all the way empty.

    I believe since i always seem to hold urine this formaldehyde compound helps rid my bladder as a proper breeding ground for uti's which is the source of my infections.

    If you cath every 4 hours i don't think that gives the product adequate time to build up the formaldehyde to do it's job.

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