Potent fertilizer
Regal Embrace had given Lex detailed instructions on what to do to absorb the elixir. He would first start using his cultivation technique, and only after he had used it for one complete cycle would he take a single sip from it, while continuing to run his technique.
As soon as he took the sip, his cultivation technique would stop absorbing spiritual energy from the air, and instead use the elixir to increase his cultivation. The actual process of what happened next was quite complicated, but all Lex needed to do was ensure he didn't stop cultivating.
As soon as he took the sip, and his cultivation technique began using the elixir to affect his body, Lex was hit with a sensation he hadn't experienced in quite a while. He needed to use the restroom, and he needed to use it now!