Lowry, currently 57th in the ranking, missed Tuesday's Pro-Am and then went to hospital, where he was placed on a drip because of his dehydration.
"Shane was pretty sick," said manager Conor Ridge. "The doctors believe he must have picked up a virus.
"He was put on a drip for dehydration. The doctors conducted a battery of tests and then after three hours he was released from hospital."
By pulling out of the event, the field - meant to be the leading 60 money-winners on the European circuit this year - was reduced to only 56.
Thomas Bjorn and Retief Goosen were not playing because of injuries and Ross Fisher has decided to focus instead on next week's PGA Tour qualifying school in California.
The downpour deposited 20mm of rain on the course in two hours, but England's Richard Finch kicked the event off at the scheduled 7.52am.
At 60th on the money list the Yorkshire golfer had squeezed in by less than £8,000 over Australian Brett Rumford, but he managed only a front nine 39.
When the action got underway Dubliner Peter Lawrie was one of the early starters making a big impression.
An eventful round of 68, which included seven birdies and three bogeys, left Lawrie on four-over-par two behind his playing partner and clubhouse leader Marc Warren.
Warren got off to a blistering start with four birdies in his opening six holes and added a fifth birdie at the 461-yard eighth and turned in 31 on five-under.
Warren reached seven under with two to play - even with a bogey at the short 13th but a further bogey saw him finish on six-under.
Further birdies came on the 12th, long 14th, where he played a brilliant chip up a bank to five feet, and 486-yard 16th, while on the 15th he hooked an iron off the tee behind a tree, chipped out and then played his approach to just three feet to save his par.
Another Irishman looking to make a big impression this weekend is three-time major winner Pádraig Harrington and he was quickly getting to grips with the Jumeirah Golf Estates course in Dubai.
Two birdies and a solitary bogey on the fron nine saw him at one-under by the turn but he began his back nine in improved fashion with birdies on 10 and 13 to go to three-under with five holes remaining.
Northern Ireland's Michael Hoey finished his opening round on two-under-par while compatriots Rory McIlroy and the newly-engaged Graeme McDowell had just kick-started their rounds without incident.
In keeping with tradition the players were sent out in reverse order, meaning Order of Merit winner Rory McIlroy was scheduled to tee off last with his nearest challenger Swede Peter Hanson.