Activella is one of the most recently introduced forms (approved in 2000)  of HRT that combines both estrogen and progestin in one pill. Both the estrogen (estradiol) and the progestin (norethrindrone acetate) are plant-based, but only the estrogen is bio-identical. (The combo of hormones is the same as in the Combi-Patch, but, of course, Activella is in oral form, not patch form.) 

With Activella, you get progestin and estradiol daily (continuous HRT), so you don't get a monthly cycle.  (Side note:  the most commonly prescribed combination continuous HRT is Prempro -- but in the case of Activella, you're getting both a different estrogen and progestin.)

On the plus side, Activella combines the popular bio-identical form of estrogen (estradiol) with a very commonly used progestin (norethindrone acetate) which tends to cause fewer side effects than other progestins.   It's rather low-dose -- on the low side of standard -- which can be a good thing, if you're wary of getting too much hormones.  But, on the flip side, it can also be a little too low for women who need higher amounts.

Because it's a continuous form of HRT, you only have to take one pill a day, and that's that.....and you typically won't get a period (although you may get some breakthrough bleeding, particularly in the first four months).

All in all, this seems to be a very good option for women who want a "one pill" approach to HRT, plant-based drugs, and bio-identical estrogen. It’s convenient (only one pill to take); and the combination tends to have fewer side effects than those with other combination therapies.

• Standard dosage: 1 mg estradiol, 0.5 mg NDA
• Pros: Bioidentical estrogen plus a progestin that often causes fewer side effects than MPA; convenient
• Cons:  Progestin isn't bio-identical to the hormones your body naturally makes; might be a bad choice if you're only recently diagnosed as it is continuous HRT, thus has a higher chance of breakthrough bleeding.