Lambie has been out of action since May 13 when he collided with teammate Rhyno Smith during the Sharks' 32-35 defeat to the Southern Kings.
There have been concerns and speculation about Lambie's future in the game, since his massive collision with Ireland's Christiaan Stander in June last year - which sidelined Lambie for four months.
"We have spent the last six weeks gathering as much information as possible, which is why we have avoided making any unsubstantiated statements in the press," said Sharks Team Doctor Alan Kourie.
"Pat has been referred to two independent specialists [concussion and neurologist] and we have also sought the opinion of a UK-based specialist, who has dealt with over 1500 cases of concussion. With clear results of both an MRI and an EEG [Electroencephalogram] all three doctors, including myself, are of the opinion that a period of three-six months without contact is necessary.
"This decision has been taken to give Pat a chance to fully recover from his symptoms, after which we have no objection to him playing again."
Explaining Lambie's symptoms, Kourie added: "He has experienced an intermittent low-grade headache, and very sensitive eyes. He was waking up feeling hungover in the mornings, but that has now passed. After a three-week course of medication and a few sessions with a physiotherapist, who focuses on the treatment of post-concussion syndrome, as well as regular physiotherapy sessions with our Sharks medical team, his headaches are almost completely resolved and his eyes are no longer as sensitive to light.
"We began a specific exercise protocol with him a few weeks ago, which he has tolerated exceptionally well and he is currently in a very positive frame of mind."
Lambie stated: "I have been exercising for 30-40 minutes a day for the last month and I started to run again last week. I also have a thorough eye and neck rehab schedule, which I am following on a daily basis at The Sharks. None of the exercise has made my symptoms worse and in fact, I feel my best whilst active.
"I will be playing rugby again and I certainly have no plans to retire. My focus for now is purely on making a full recovery and getting fit and strong again. Once the three-month rest period has been completed, I will be reassessed to determine where we are in terms of the rugby calendar for the rest of the 2017 season.
“I would like to thank both the Sharks and SA Rugby for their patience and concern for me. I have been cared for and looked after extremely well and I am grateful for their constant support. The fact that both parties have not put any pressure on me to get back on the field, until I fully recover, makes the world of difference with my recovery."