Backstrom tested positive for the substance psuedoephedrine - contained in the allergy medicine Zyrtec-D - which he has been taking for seven years.
The test was taken after Sweden's quarter-final match against Slovenia and Backstrom was listed on the original Sweden line-up for the final before his name then disappeared on a revised team sheet ahead of Canada's 3-0 win at the Bolshoy Ice Dome.
Blackstrom told a press conference after the final: "I have absolutely nothing to hide. I have allergy problems, and I have been taking Zyrtec-D for many years, and it was a little shocking to me to be honest with you.
"I feel like I haven't done anything differently now than the last seven years. I've been playing internationally for many years and I haven't seen this before.
"I was ready to play probably the biggest game of my career, and two and a half hours before the game I got pulled aside.
"I was very sad, and honestly I felt bad for the guys. Lots of guys were in the locker room when they called me out."
Asked about this testing history, Backstrom replied: "In NHL I've been tested twice already and by the IOC once before in January, so that's under the same medication.
"I've taken this for seven years. We're pretty much getting tested four times a year in the NHL. I was tested after the quarter-final against Slovenia."
Sweden team doctor Bjorn Waldeback said of Backstrom's medication: "He has problems with sinusitis and allergic problems. He has for several years taken one pill a day of medication called Zyrtec-D. It contains psuedoephedrine."
"We have told them he has taken this medication, one pill every day, as he has done previously and he also did this time."
IIHF chief medical officer Mark Aubrey said: "I think we feel strongly after having heard from Bjorn (Swedish Olympic Committee spokesman Bjorn Folin) that he (Backstrom) is an innocent victim of circumstances, certainly from a doping control standpoint.
"He has undergone a doping control test. On the medical form the form asks the athlete to list all medications he has taken in the last seven days, Nicklas has provided the information correctly, putting the medication down."
"He has been treated for medical problems and has been taking that medication to help his medical condition. That substance is only banned if it goes over a level of 150 nanograms per millilitre. So we do not ban all players that have that substance, only if they go over."
Asked what the level of Backstrom's test had been, Aubrey replied: "We understand it was around 190.
"I feel strongly as a medical person that there certainly is no doping in this instance. He is an innocent victim. Doping is certainly not allowed, but this is not a case of doping."
Sweden general manager Tommy Boustedt said he had received a call at 1330 local time from the Swedish Olympic Committee informing him that Backstrom had to attend a hearing at 1400.
Boustedt, who watched the final with Backstrom on television at the Olympic Village, said: "I talk for the players, I talk for the coaches and the whole staff, they're all very upset today. Our opinion is that IOC has destroyed one of the greatest hockey days in Swedish history.
"I've spoken to Nicklas and I'm pretty sure that he and his lawyers will take this further."
Asked how Sunday's event could affect participation of NHL players in the Olympic Games going forwards, Boustedt replied: "This can further jeopardise participation of NHL players in Olympic Games because I know that both that NHL and NHLPA are incredibly upset about this, seeing this as an attack on their business too."
Sweden coach Pat Marts was unhappy about losing Backstrom just two hours before the final started.
"At 1345 I was on my way to the game when I got a call that Nicklas Backstrom was called in for a hearing.
"I didn't get a definite decision that he couldn't play until during the warm-up, so then we had to just take it from there. It feels like a great miscarriage of justice.
"IIHF (International Ice Hockey Federation) have doctors here who said that they thought Nicklas should play but the International Olympic Committee said he shouldn't.
"This is something you should get notified on within 24 hours, so if you get to hear about it two hours before the game it's just rude. "
NHL deputy commissioner Bill Daly issued a statement on Backstrom's failed test which read: "We understand that Nicklas Backstrom tested positive for a substance banned 'in competition' by the International Olympic Committee.
"It is our further understanding that the positive test was the result of a common allergy medication taken by the player knowingly, with the approval of the team doctor and without the intention of gaining an illegal or improper performance-enhancing benefit.
"In addition, the specific substance that resulted in the positive test is not currently on the League's prohibited substances list.
"Subject to confirmation of the facts as we understand them, and given the fact that the substance is neither prohibited in the NHL nor was used in an improper manner here, we do not anticipate there being any consequences relative to Nicklas' eligibility to participate in games for the Washington Capitals."
Backstrom's failed test is the sixth doping case to emerge in the final few days of the Games.
German biathlete Evi Sachenbacher-Stehle tested positive for banned stimulant methylhexaneamine, Ukrainian cross country skier Marina Lisogor was thrown out of the Games after a positive test for the banned substance trimetazidine and Austrian cross-country skier Johannes Duer tested positive for EPO in a pre-competition doping control in Austria on February 16 and was withdrawn from Sunday's men's 50km mass start free race.
Italian bobsledder William Frullani tested positive for a banned stimulant - traces of dimethylpentylamine, found in dietary supplements, were discovered - and Latvian men's ice hockey player Vitalijs Pavlovs also tested positive for methylhexaneamine.