After the birth control implant is inserted how long does it take to take effect?

It depends: If you had the implant inserted during the first 5 days of your period, then it should be effective immediately. If it was later than that in your cycle, then you should use a back up method ;#40;condoms;#41; for at least a week after insertion.

1 week: The birth control implant (Implanon/Nexplanon) is extremely safe because it only releases the progestin, Etonogestrel. There is no estrogen and so the risk of clots is MUCH lower than any combined method. Failure rate is 0.05% in a year, which is almost better than getting your tubes tied. It is effective within a week of insertion and won't be affected by ANY antibiotics (except rifampin).