Medical expenses - Can you claim medical expenses you have not paid yet but were billed in 2016

[onealb]

I have a lot of medical bills from 2016 but I have not paid them all yet. Can I add them to my deductions if I have been billed for them and just not paid yet or can they only be added if they have been paid?

[VolvoGirl]

Just what you actually paid in 2016 or  was charged to your credit card.