Since Damon looked deep into Elena's eyes and told her that he would become human with her, the internet has been aflame with concern for what will happen to the ancient vampire if he decides to take the cure.
After Katherine's death from rapid ageing after taking the cure, some The Vampire Diaries fans are worried that Damon would suffer the same fate seeing as he is over a hundred years old, but it's important to remember it wasn't the cure itself that caused Katherine's rapid descent into old age.
If you cast your mind back to Season 5, it was months before Katherine returned to Mystic Falls after Elena forced the cure down her throat and at that point she was totally unharmed (despite the best effort of her numerous enemies).
It was only after Silas had drained Katherine of her blood so that he could imbibe the cure himself, that the disturbing events including her hair turning grey and her teeth falling out occurred, as you can see in the video of the Petrova doppelgänger receiving her diagnosis below:
This means that if Damon does take the cure, he will be safe, but if he is drained he will be vulnerable to the same fate as Katherine faced on her penultimate death.
Of course, we have no idea on the effects of taking just half a cure, but chugging down a whole one should, in theory, post no problems to Damon's health.
Of course, The Vampire Diaries writers have been known to twist the mythology and open up loop holes at will, but technically, this is how taking the cure should go down!