Candreva slammed the ball into an empty net in the 62nd minute after a glaring error from Joe Hart, who failed to claim Cristian Ansaldi's pinpoint cross.
Afriyie Acquah had given Torino the lead after Daniele Baselli had cancelled out Geoffrey Kondogbia's fine solo opener before the break.
"At this point, the Champions League is further away, because the teams ahead of us are not slowing down," Inter coach Stefano Pioli told Italian broadcaster Mediaset Premium.
"I expected more today, perhaps more sharpness. "We need to prepare for the final sprint, win as many matches as possible and then see where we are at the end," he added.
"Getting third wasn't going to be easy, but we had the chances to win." Inter travelled to Turin on the back of last weekend's eye-catching 7-1 victory over Atalanta, and started brightly, taking the lead in the 27th minute through Kondogbia when he cut in from the right, outmuscled two defenders and slammed home past the culpable Hart, who managed to get a hand to the ball.
Read the full article on eurosport.co.uk: Inter's Champions League hopes dented with Torino draw