Can I obtain and use a scrip for a stair lift AFTER it has been installed?

I have spinal arthritis. Late last Fall I had a cardiopulmonary effusion. When I got out of the hospital I had a stair lifter installed. If I didn't have it I would have to crawl up the stairs on all fours.  Can I ask for a script NOW and use it to deduct the cost of the stair lift as a medical expense. Can I also do that for the safety railings I had installed?