When I was in for my bowel tumour in 2013 I was told to shower with Octenisan for 2-3 days beforehand, but they didn't give me any, I had to get my own from the pharmacy. I don't recall it feeling any different to any other soap. When I was in for a cystoscopy 18 months ago I wasn't asked to do anything, and I don't think I was asked to use it when I had my cardiac ablation in 2015 either. All my other admissions have been unplanned, although it's always Octenisan in the shower cubicles on the wards.
A few years ago I was in the shower at home and suddenly felt as if there was a freezing cold draught, but I couldn't work out where from. Next day it was the same, and I realised it was the shampoo I was using that was causing it: it contained menthol. It was a 'sport' version of the stuff I used regularly, and I hadn't noticed there were two versions, I didn't like it much, but decided to use it all up rather than throw it away. That was fine, but after 3-4 weeks my ears started bleeding, and they stopped doing it when I quit using the shampoo.
After a few months, the non-mentholated version I'd been using for years without any problem also started making my ears bleed, so I stopped using that as well. I haven't had any more trouble since.