Prince, who died at the age of 57 at his Paisley Park compound in Minnesota, had reportedly been battling the flu since 7 April this year and had cancelled two shows in Atlanta around the time.
He went on to perform these shows on 14 April, but on his return home the following day his plane made an unscheduled stop at Quad-City International Airport in Moline in Illinois where he was taken to Trinity Moline medical centre for about three hours and was reportedly suffering from "bad dehydration".
CNN reports that, in addition to battling the flu, Prince had "walking pneumonia".
Pneumonia is inflammation of the lungs, and walking pneumonia is a non-medical term that refers to a mild case of pneumonia. It's called walking pneumonia because people can go about their regular day-to-day activities, although they do feel run-down.
It can last for quite a long time and symptoms include a bad cough, fever, chills, headaches and abdominal pain.
Bacterial pneumonia can invade and kill heart cells, increasing your risk for heart failure.
Read: Flu is coming – time to get your shot
Hollywoodlife reports that Prince did not heed his friends' advice to "take it easy" in his last days, and visited a pharmacy shortly before his death. It was the fourth time he'd been there that week, the gossip website stated.
For most of us, contracting flu – a contagious respiratory illness that can cause mild to severe illness – is an unpleasant experience from which we recover within a few days or at most a couple of weeks.
Complications like pneumonia
For children, the elderly and those individuals who have weakened immune systems flu can be serious and complications can even be deadly," says Dr Jacques Snyman.
He says children under the age of five, the elderly, HIV-positive individuals, diabetes and asthma sufferers may be at particular high risk of developing serious complications such as pneumonia.
For that reason, it is recommended that at-risk individuals visit a chemist or their GP for their annual flu vaccination.
Read: Why flu triggers asthma
In a typical flu season, flu complications – including pneumonia – send more than 200,000 Americans to the hospital. Death rates linked to flu vary annually, but have gone as high as 49 000 deaths in a year, the Centres for Disease Control in the US reports.
An autopsy will be performed on Friday to determine the cause of the singer's death.
Prince, who was a teetotalling vegan and a Jehovah's Witness, was in the news in 2009 for allegedly refusing double hip replacement surgery as his religion prohibits blood transfusions. He was known to suffer from hip injuries, possibly sustained by energetic jumping on stage, often in high heels and from varying heights.In April 2009 Prince talked to People Magazine about his struggle with epilepsy as a child, but reports say that he outgrew this disease.
Less credible entertainment websites have reported that Prince had been taking illegal drugs, or overdosed on painkillers, which was why he made the stop in Moline, and that he was HIV positive. Neither of these rumours can be substantiated, so remain pure speculation.
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