Comment by preg_match

Yes, you require analgesics for general anesthesia, it’s not optional.

The reason synthetic opioids like fentanyl are used is because they actually have less side effects. Opioids can cause a histamine response, digestive issues and constipation. Newer synthetic and hybrid opioids cause that less, so they’re preferred in hospital settings.

There’s essentially no long term risk with the small doses required during surgery. The main risk is, of course, acute respiratory depression, which kills you. This is how opioid overdoses happen. This doesn’t happen under GA because the dose is tightly controlled, and your airway is supported anyway; you’re intubated.