Improvements to your home are generally not deductible as medical expenses, but they increase the value of your home (adjusted cost basis), which may reduce your capital gains later when you sell.
Improvements are only deductible if the cost of the improvement is more than the amount that it increases the value of your home. This might require a real estate professional to help you out. For example, if a handicapped shower makes your home more marketable and adds $5000 to the asking price, and cost $8000 to install, then you can deduct $3000. If the improvement does not increase your home's value at all, then it is fully deductible. There is more information about this in publication 502.
https://www.irs.gov/publications/p502
