^ no amount of being 'in tune with your body' can rule out the placebo effect. Whether you consciously believed something will work or not is in fact irrelevant. In large doses, loperamide generally takes around 2 hours to kick in for most people so I am skeptical of your experience. I am not saying it's impossible but I just wanted to point out that there is no earthly possible way for you to know if you are experiencing a placebo effect (if you could, it wouldn't be the placebo effect essentially by definition). Nearly everyone believes that they are insusceptible to the placebo effect while nearly everyone is to varying degrees.
I have a lot of experience with loperamide (primarily to hold me when I was physically dependent on opioids for pain as well as to try to achieve pain relief long after I got off daily prescription opioids. I know it works in the right doses. Many claim it doesn't pass the BBB but in reality it does however almost all of it is exported back over due to P-glycoprotein producing almost solely peripheral opioid agonism at therapeutic doses. In large enough doses, enough is not transported back to produce central opioid effects albeit effects that most do not find to produce euphoria on par with most classical opioids and opiates.
When you take very large doses that produce central effects, loperamide still binds much more strongly to opioid receptors in the gastrointestinal tract so you really need to be aware of the potential to cause severe constipation and if used enough, an obstructed bowel. With a single large dose (especially when you don't possess a tolerance to opioids), constipation can last for a few days and the best way to counter this is with a combination of a stimulant laxative such as sennosides or bisacodyl and an osmotic such as polyethylene glycol 3350. The former stimulates peristalsis and the latter increases water in the colon (the opposite effect that opioids have).
Over and over you see people recommend fiber for those suffering from opioid-induced constipation and this is quite counter-productive. Bulk-forming agents, as they are referred to, are great for people experiencing constipation primarily due to their diet but if someone is constipated due to opioids, this adds more material that needs to be passed without increasing the water in the intestines resulting in even more painful constipation, defecation and a higher risk for bowel obstruction. In simple terms, when you're backed up from opioids and ingest a lost of fiber, you're painfully going to shit a brick and very well could end up with anal fissures and/or hemorrhoids.
