The Royals climbed to fifth place on the back of their point, but knew that victory would have taken them clear of their promotion rivals.
And the home side should have secured the three points after carving out the better chances in a tight game.
Andy Hughes nearly won it at the death for Reading, but saw his shot blocked by Paddy Kenny's legs after substitute Les Ferdinand had flicked a header into his path.
And both sides had chances in an evenly-contested first half, Reading hitting the woodwork and the Blades seeing an effort scrambled off the line.
Recalled Reading striker Nicky Forster, making his first start since February after being dropped by manager Steve Coppell, was the home side's most dangerous outlet.
He lashed Reading's first chance of the game well wide but was desperately unlucky not to open the scoring with a dipping volley that flew just over after Steve Sidwell's precise pass.
Sidwell himself dragged one shot wide agonisingly wide and saw another fly straight at Kenny, but the home side had a major let-off midway through the first half.
Steve Kabba tricked his way down the right and his low cross was only half-cleared by Ibrahim Sonko, who was relieved to see Andy Gray's resulting shot blocked on the line by Reading skipper Graeme Murty.
A minute later, the luckless Forster saw his low shot thud against the outside of a post and, as Forster faded in the heat, so did Reading's chances of victory.
Sonko might have won it but fluffed a free header from a Ricky Newman corne while, at the other end, Kabba's header was easily saved by Marcus Hahnemann.