Okay, maybe there's no association at all, but since it appears to be a possibility, I thought I would run this thing up the flag pole and see who salutes.

Many years ago, a tenant of mine told me an interesting story about how Dr. Bronner's led to a painful and serious aggravation of a skin rash he had picked up in Australia. His physician found the episode to be predictable and funny; my tenant did not find it to be either.

I put the story out of my mind until recently. In over 40 years of cycling (just shy of 500,000 miles), I had never had any issue with saddle sores until I got one on a tour a couple of years ago. I initially thought it was some combination of age, a sharp increase in mileage while on tour and replacing my saddle just days before leaving on a trip (the old one broke). After that tour, I healed up just fine. Then, it happened again on the next tour. Well, I'm still old, but the other two conditions were not applicable. Then it happened again. Getting old is starting to be a pain in the ass. I should note that the only soap I bring on bike tours is Dr. Bronner's and I use it for everything (laundry, body, hair (what's left of it), dishes).

About that time, I began to wash my cycling shorts in the shower with Dr. Bronner's soap at home as well as on tour. Interestingly enough, I began to develop saddle sores on a regular basis. My math major son suggested to me that one plus one equals two, so I stopped using Dr. Bronner's a few months ago. The saddle sores stopped appearing. Then, two weeks ago my wife and I did a short overnight ride to the beach for the week-end (90 miles each way). The only soap we brought was Dr. Bronner's. Guess who got a saddle sore on the ride home.

So, maybe by rear-end is weird. Maybe this is all just a coincidence. Either way, I'm done with the good Dr. Has anyone else ever had something like this?

I use Bronners on tour, and have developed a rash when washing shorts in a sink, but I figured it was because I was not rinsing it well enough.
Whenever possible, I try to use a machine to wash, or failing that just really rinse well. Generaly use a few drops of Bronners in the machine on tour, no problems.

I got a liter of Betadyne surgeon's scrub to wash 'down there',
and knock back skin surface bacteria.

Why change what you do normally at home?

Have you had a look to see what the chemicals are used to make Dr Bronners, and compared them to what you use in ordinary soaps or washing detergents? And have you researched to see if Dr Bronners changed its formula about the time you started to develop saddle sores?

And what sort of saddles sores are they -- the deep-seated lump, the hair follicle irritation or the skin rash type?

FWIW, baby shampoo works fine for washing hair, body, dishes, and clothing (including in a washing machine). It is pretty convenient as an only soap to carry on tour. It probably even works fine for shaving as well, but since I don't shave on tour and just use plain water at home I am not the one to say.

Campsuds are OK for all of those purposes as well.

Personally I think that Dr. Bronners was inferior to both of the above choices.

Oh and one other thing... For saddle soreness Balmex or other zinc oxide based diaper creme worn overnight works like magic.

I can see why folks would want to do that, I know that I do. They may use quite a few different soap products for various purposes at home. In all probability they use something different for hair, body, dishes, shaving, and clothing. So probably at least 5. Carrying just one on tour is a very attractive alternative.

You might be having a reaction to one of the ingredients.

Dr. Bronner's Castille soap contains Tocopherol, a class of chemical compounds related to Vitamin E. It is probably included as a preservative, as Tocopherols prevent oils from becoming rancid. (The peppermint soap contains, according to the label, coconut, olive, hemp, jojoba and peppermint oils.)

Some individuals have allergic reactions or develop rashes and hives when Vitamin E is used topically (on the skin). See:

https://www.dermweb.com/skintherapy/stl0103.html#RTFToC6

Excerpts:

"Onset of symptoms was 1-160 days (median 14 days) after first use of the cosmetics. The lesions were long lasting, widely distributed, associated with a pronounced pruritus, and frequently aggravated by sweating, solar irradiation, or heat. The rash subsided within 1-4 weeks following topical or oral corticosteroid treatment but sometimes relapsed after sun exposure."

[Interesting about the sweating and heat, which are typical during a bike tour...]

"Mennen's "E" deodorant aerosol caused so many cases of allergic contact dermatitis that it was withdrawn from the market."

"Thus, as well as limited utility, topical vitamin E can produce a completely opposite reaction to that intended, damaging the skin rather than "improving" it. Therefore, so-called natural vitamins are no different from many other cosmetic ingredients: they all have the potential for allergic reactions, some of which could be atypical."

I can easily believe Dr. Bronner's would do that. That stuff is really harsh, in spite of what it says on the label. We used to wash our floors with it, but that's about all. We bring Biokleen All Purpose Cleaner for biking and hiking. It's a surfactant rather than a detergent or soap. Works great for everything. We usually do our laundry with the shampoo provided when we stop at a hotel or pension, using the wind-the-towel technique. We also bring Tegrin shampoo for private part washing - actually I wash my whole body with it. Best anti-saddle sore treatment there is.

As to why I would use something different on the road than at home, it wasn't really a conscious choice. I generally just grab some form of liquid soap, put it into a small container and use it. I'm not sure if I had ever used DB peppermint before this whole series of events, but it became a default soap around the house for things like pot scrubbing and such a few years back. It is now being replaced with BioKleen, which does not appear to cause me any woe.

The sores were not the deep, apoxic-induced deep-tissue sort. They were the infected, inflamed skin lesion kind. You haven't lived until you've ridden a few hundred miles with bloody, oozing saddle sores and a leather chamois.

OOoooo... no THANK YOU!!!