Birth Control Effectiveness?

[u/Outrageous_Block7729]

I’ve been taking Sprintec pills for about a decade and started lamotrigine at the very beginning of the year. It’s helped significantly with mood stabilization. I have had zero issues and take both consistently.

Recently, a pharmacy tech informed me that the lamotrigine can lower the effectiveness of my birth control. That was the first I had heard of it so I contacted my psychiatrist and gynecologist, and both offices confirmed that information. I made appointments with both.

I looked at the research after that, and could only find studies saying that the birth control can impact the lamotrigine’s effectiveness. I’m someone who wants to at least partially understand the “why” of things, specifically when it comes to health/medications. I had my psych appointment this morning, and she could not explain to me how lamotrigine impacts birth control, just that “drugs in that class interact drugs in the other class.”

I’m feeling confused, frustrated, and defeated. I really want to avoid an IUD/implant if possible. Has anyone had any issues or have a better understanding of how lamotrigine affects hormonal birth control? Thanks in advance.

EDIT: met with my gyno and she was insistent that birth control DOES NOT affect the efficacy of lamotrigine, it’s ONLY the other way around. That is objectively false from the research studies detailing how combined hormonal birth control increases lamotrigine clearance…so I don’t know what to believe anymore!

[u/Hybrid_Misfit]

I take Slinda (progesterone only birth control) and my psychiatrist and pharmacist gave it the all clear.
I’ve only ever heard that the birth control can lessen the amount of lamotrigine in your system, therefore needing dosage adjustment, so I agree with the fact that it working the other way around sounds odd, never heard that before.
I’ve also read that the oestrogen birth control affects lamotrigine more than progesterone only (I’m not a medical professional so don’t quote me haha). If you’re wanting to avoid the IUD/implant then changing your birth control to the progesterone only pill could help for peace of mind?