No-one at the private hospital Ronaldo is currently said to be a patient at could be contacted on Sunday afternoon for comment.
Ronaldo, regarded as one of the world’s best-ever players, owns a house in Ibiza and is a regular visitor to the island.
He is believed to have arrived in Ibiza for a summer break a few days ago.
Ronaldo went down with dengue fever in January 2012 and posted a picture of himself on Twitter hooked up to a drip in hospital alongside the message: “Good morning to all those who began the New Year with dengue.”
He retired from football in 2011 after a glittering career with Barcelona, Inter Milan and Real Madrid.