16 days post hair transplant and have been using T-Gel shampoo. Is it okay to use this or will the follicles be damaged?

It is best to contact your surgeon for post surgery issues and care since all doctors have slightly different instructions.

I would recommend using Nioxin shampoo. It works really well and you can find it at any beauty supply store. 

I would recommend a mild conditioning shampoo after hair graft surgery-Shampooing gently is okay after second day of grafting.  T-gel may irritate your scalp a bit and would avoid that shampoo for about 6 weeks after your procedure.  I would get advice from you hair graft doctors on which shampoo they recommend as we give all our patients hair products to use after their procedure to give the best recovery for their grafts.  Good luck with your recovery.

You may start to wash your transplant area at second day of surgery with care and massage the transplant area gently so the scabs will fall off... After two weeks of hair transplantation  it is acceptable  to wash hairs as normal /preoperative period of surgery. All scabs should be cleaned with pressured (not gentle) massage to transplant area  after 2 weeks .Dont forget that you may wash your head with normal pressure and if you need you can use a wet towel with soap for massage the scabby area, it Works very well to remove scabs .Patient may feel free to loosen any scabs on his/her head by massaging and that will not  damage the grafts after 2 weeks . 

T gel is ok to use at 16 days post op and it shhould reduce the flaking and itchyness that you might have