I Had a Brow Lift Using Screws and Two Years After Surgery my Head Started to Swell in That Region?

It is unlikely that your body is "rejecting" the screw. More likely is that it may have become infected. Follow up with the surgeon. It is important to know what type of screws were used so that your surgeon can have the proper tools to remove them.

inflamation following browlift or foreheadlift with screws

titanium screws rarely cause problems.  they are used everywhere in the body permanantly.

none the less.  ongoing foreign body reaction may require complete removal.

Titanium screws are pretty inert. If you developed a local infection then that could lead to persistent swelling. An evaluation is in order possibly with studies and ultimately removal of the screw.

Since your surgeon tried drilling the screws in even further they were likely made out of titanium.  Titanium is very well tolerated by the body if it is rigidly fixed (i.e. not loose).  If titanium is loose it can become infected and the treatment is to remove the screws.  If the screws were absorbable there can be some foreign body reaction as the screw degrades and this can also be scraped out and removed.  Please follow up with your surgeon to have this checked out. 

It is not rare that the body can react to any indwelling foreign material. If there are persistent inflammatory reactions that is an indication that the resolution of the problem is going to be the complete removal of the material. It would be helpful to know what type of screws were used for your browlift surgery.