I had implanon inserted Sept '10. In the middle of June, I came down with mono which lasted for a little over a month. My fiancé and I did have unprotected sex during that time but I thought nothing of it. I'm beginning to wonder though because I'm having abdomen pain as well as fatigue and nausea. I can also smell really well, which I didn't even think about until my fiancé pointed it out(we were in the car and I could smell the wood from the vehicle in front of us) and now I'm either just being paranoid or I am pregnant. Now, my question is not "Am I pregnant?". I'll buy a test if I really think there's a possibility. My question is, does mono have any sort of affect on Implanon, such as making it not work?

There is always a possibility when you have intercourse. No form of protection is 100% effective 100% of the time.

Buy the test and use first morning urine.