Curtis Pitt struggled to maintain control of Wednesday's rowdy chamber during a fiery Question Time the day after the state budget.
He arrived late and multiple MPs from both sides of the political aisle raised concerns, knowing he returned from a mental health break on Tuesday.
"Speaker is independent, so cannot be forced to vacate chair," one MP told AAP in a text message.
"Strong advice has been given but he makes his own decision."
Mr Pitt left the chamber after Question Time and said in a statement he was taking strong pain medication for severe back pain.
"As a consequence of my ongoing medical issues, I have decided to take a further period of leave," the statement read.
"I am suffering from severe back problems and will soon be undertaking scheduled surgery.
"Consequently, I am taking strong pain relief medication on an as-required basis to manage this condition which can at times, manifest in different ways, including the onset of drowsiness.
Mr Pitt said he attended a Government House function on Tuesday night but left early to return to Parliament House by 7pm and was not drunk.
"I've had a lot on my plate," he told Nine News on Wednesday.
"Today was very challenging for me because I had severe back pain."
When asked whether alcohol played any part in his appearance during Question Time, Mr Pitt replied: "No, no. To be very clear, absolutely not."
"I'm sorry if there's been any reflection on the office that I hold (and) also in terms of the way that parliament was conducted."
Mr Pitt previously took a hiatus, citing family and mental health issues.
On the eve of his return to parliament, the five-term MP posted a picture of four Superman models, saying it was essential to seek help and not everyone had to be a man of steel.
Mr Pitt went on leave after May's Cairns sittings of regional parliament in his electorate of Mulgrave.
He later took to social media to admit he was "not doing as well emotionally as I've made out to anyone" after a divorce from a two-decade marriage and dealing with ulcerative colitis, depression and his parents' serious health issues.
Mr Pitt thanked people for their support when he returned to the chair on Tuesday.
Deputy Speaker Joe Kelly will act as Speaker.
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