Torino's Iago Falque scored his fourth goal in his last six league games with an excellent individual effort in the second half, as missed chances and an impressive performance from Torino goalkeeper Salvatore Sirigu frustrated Inter.
But Eder, who signed a new contract last week, smashed in from close range with 11 minutes remaining to salvage a point and make it 12 league games without defeat for the hosts going into the international break.
Luciano Spalletti's men had won nine and drawn two of their first 11 league games this season, but after the head coach had to dismiss comparisons with club icon Jose Mourinho in the build-up to the game, this result will also serve to temper expectations.
Inter could have gone top with a victory ahead of the day's other Serie A matches, but fell to third after Juventus defeated Benevento 2-1.
Unbeaten leaders Napoli, meanwhile, were away to Chievo and stayed two points clear of Inter after a 0-0 draw.
Torino are seventh in the table after making it four points from their last two games.
The visitors were the first to threaten when a left-footed strike from Daniele Baselli forced Samir Handanovic to get down sharply to save and just about hold on.
After being found by Antonio Candreva, Mauro Icardi scuffed a shot straight at Sirigu at the other end, while Roberto Gagliardini fired over with 30-yard drive.
Inter then created an excellent chance, with a corner from the left flicked on by Matias Vecino into the path of Milan Skriniar, whose looping header looked destined to find the top corner until Sirigu produced a superb fingertip save.
Handanovic then produced similar heroics at the other end, with the home goalkeeper at full stretch to tip away Baselli's flicked header after excellent work from Cristian Ansaldi down the left to create the opportunity.
It was Sirigu's turn to shine again early in the second half, the 30-year-old producing a reaction save to keep out Vecino's header from Yuto Nagatomo's left-wing cross.
And that proved crucial when Torino moved in front just before the hour mark, Falque collecting a pass from Lorenzo De Silvestri and dribbling inside from the right past the challenges of Miranda and Gagliardini before firing a left-footed effort into the bottom corner from 20 yards.
Icardi almost responded when he showed composure to beat Nicolas N'Koulou in the penalty area, only to blaze over his finish.
Torino should have put the game to bed when Joel Obi somehow headed Adem Ljajic's free-kick wide from two yards against his former club and an end-to-end battle continued when an aerial effort from Skriniar was just off target for Inter.
The visitors' star man Andrea Belotti was relatively quiet and should have done better when he dragged a shot wide on the break as the match entered its closing stages.
And Inter grabbed a leveller soon after as Ivan Perisic's cross was cushioned into the path of Eder by Icardi, the Italy international finding the top corner from six yards just 10 minutes after coming on for Gagliardini, his first goal of the season.
There was almost a dramatic winner for Inter as Vecino, from oceans of space, smashed an effort against the top of the crossbar from 30 yards, but the visitors held on for a point.
Key Opta stats:
- Inter have been unbeaten in their first 12 league games for the first time since 2007-2008.
- Torino have conceded a goal in all of their last nine league games.
- Inter have scored 10 goals in the last 15 minutes, more than any other team in this Serie A.
- Iago Falque scored with his only shot in this game.
- Mauro Icardi has delivered an assist in Serie A for the first time since January against Pescara.