I believe that it's the hormone level that keeps you from flaring quite so bad. I went on birth control (Ortho Trycline) in 1996, and I've been on them ever since. They switched me to the low dose (Ortho Tricycline-Lo) a couple of years ago.

As soon as they switched me over, I started having vertigo, fatigue and numbness/tingling. I thought I must be going through early menopause! It didn't get really bad until last year - lots of stress, brown recluse spider bite, and a flu bug set something off, and I ended up with a big flare (and a diagnosis.)

I've heard good things about Estriol, which is a female hormone replacement.