I'm immediately reminded of these lines from A Christmas Story:
Ralphie as an Adult: [narrating] Over the years I got to be quite a connoisseur of soap. My personal preference was for Lux, but I found Palmolive had a nice, piquant after-dinner flavor - heady, but with just a touch of mellow smoothness. Lifebuoy, on the other hand...
Ralphie: YECCHH!
And this:
[During Ralphie's daydream where he went blind]
Mr. Parker:
What happened son? Who did this to you?
Ralphie:
It,it was... soap poisoning!
[Mr. & Mrs. Parker begin wailing]
Ralphie:
Don't worry. We'll make it though... somehow.
Mr. Parker:
I told you not to use Lifebuoy!
Butt seriously!
The worst thing I've ever experienced is a “closed-down” rectum from an extremely strong soapy enema (grated Ivory dissolved in very warm water to the very edge of solubility). It was so strong that the cooling of the liquid in the tube caused the soapy mixture to congeal to a milky white viscous liquid that had difficulty flowing if the clamp was closed too much. It was what I called a self-sealing enema because it was very difficult to expel since my rectum was both very sensitized and it was closed down pretty tightly. I could barely get my smallest diameter nozzle in deep enough to start multiple rinses to dilute what I had taken in. Oh, and there was nausea since the reaction was so intense. Eventually, I was sitting on the toilet with an empty trash can in front of me, just in case.
I was shedding a stringy mess of my colon lining for the next two days. And a bit gassy as well.
The irritating effects of the alkaline and slightly basic (pH) nature of the liquid does intensify the eventual contractions that come with such enemas. I had found that liquid soaps produce a more intense effect than solid soaps until I got that dialed in.
I've never tasted the soap after an enema, though I have been able to smell the scent coming off my skin (most notably peppermint). But other than those specific aspects, I haven't noted any other effects.