These are still tax free. Qualified medical expenses include those of an individual who could have been claimed as a dependent on your tax return except that the individual had gross income of more the $4,050 (in 2017). Expenses of this individual continue to be qualified medical expenses as long as they meet the other requirements for being your dependent.
See Qualified Medical Expenses in IRS Pub 969: https://www.irs.gov/publications/p969#en_US_2016_publink1000204083
