On nexplanon and have had a lot of breakthrough bleeding. would vitamin c help breakthrough bleeding while on nexplanon?

No: Vitamin C will not help. Consult your GYN

Doubtful: From what I understand, using Vitamin C around the time of breakthrough bleeding helps by helping your body better absorb estrogen, which might help you if you were using estrogen as part of your birth control regimen. But the Nexplanon is progestin-only and that's why I'm not sure the Vitamin C would help at all because it does not release estrogen, just the progestin.