You said that biliary colic is a side effect of opiods when it acts on meu receptors…
Earlier it was commented that Opiods causes worsening of pain in biliary colic due to constriction of sphincter of Oddi.
But recent studies have shown that the benefit of pain relief is far more than the Side effect.
Thats why Morphine is used now a days. Sir has already cleared that few weeks back on youtube session.