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Yes, there are health implications. First of all, both of you will be on medication for a long time afterwards. Then there's no guarantee that the donated kidney will keep the recipient alive for long. If possible, maybe up to three or four years, under strict medical supervision.
Also, from having a capacity to function at 100% energy level, the donor will be left with 40%, so there will be limitations to the sort of work or activities, that the donor can do. Not too much hard work or stress.
The safest way to know more, is by speaking with the health professionals who will run the tests to know if there is a match for the donation to be made in the first place.