I didn’t tolerate the pill well. Will HRT affect me the same way?

Not necessarily. The birth control pill is a combination of high doses of synthetic hormones (unlike those produced by the ovary), enough that the brain tells the ovaries not to make any hormones, which leads to no ovulation—and therefore, effective birth control. In this situation the hormones your body is “seeing” are entirely from the pill. In contrast, HT (hormone therapy) is significantly less hormone and is in the form that is identical to what your ovary has been making (or “bioidentical”). With HT we no longer need to suppress the ovary, we need to replace the ovary hormone-production function. These factors significantly influence tolerability and effectiveness of the treatments.

Hormone replacement therapy (HRT), however, adds hormones to the supply your body makes on its own. After menopause, your ovaries still make hormones, but far fewer than before—no progesterone, nearly no estrogen, and some testosterone. In addition, after menopause, hormone levels don’t fluctuate as much. Because of those two differences, your body may respond better to HRT than it did when you tried the pill.Talk to your doctor about what's right for you.

One additional note for women who can tolerate the pill: If you’re in perimenopause and have  irregular bleeding, the pill might bring some relief. Typically, a doctor will prescribe the pill rather than HRT during perimenopause because your body’s hormone production may be “all over the place.” As always, talk to your doctor about what’s right for you.