The Premier League giants confirmed that Smalling had fainted after feeling unwell while visiting the popular Indonesian tourist destination.
Prior to United's statement, there had been various reports speculating what had caused the 26-year-old’s head injury, with some suggesting he had hit his head during a surfing lesson while other reports pointing to a jellyfish sting.
“We can clarify Chris Smalling has had food poisoning during his holiday which resulted in him fainting on Sunday,” a club statement said. “He was taken to hospital and is now feeling fine.”
Images of the United centre-back have emerged on social media, showing him signing a club jersey with bandages on his head and wrist, and a brace around his neck.
With Smalling on the road to recovery, United confirmed that he will be reporting for pre-season later this month.
The Red Devils, under new coach Jose Mourinho, face Bournemouth in their first League fixture of the 2016/17 campaign on 13 August.