These are all the newer improved estrogen patches. Like the reservoir patches that were first designed, thest patches continuously release natural, bio-identical estrogen into your system, but they tend to cause less skin irritation. According to one manufacturer, only about 9 percent of users developed significant skin irritation -- about half that of Estraderm reservoir patch users. The matrix patch was first introduced in 1995, when the Climara patch came out. A year later, the makers of the Estraderm patch came out with their version of a matrix patch, Vivelle. Next came Fempatch, a lower dose estrogen patch. And most recently Vivelle came out with a new super-tiny patch -- the Vivelle dot, about the size of a nickel or postage stamp.

In all cases, the patch doesn’t have the bubble that the Estraderm TTS patch does. Instead, it’s a flat, translucent patch that lies flat under your clothes and sticks better -- even when you shower or swim. In addition, the matrix delivery system appears to deliver estrogen more steadily, maintaining more stable blood levels of estrogen. But you get a slightly lower level of estrogen in your blood from the matrix patch than you do with the reservoir patch Estraderm TTS -- about 70 picograms of estradiol from the .1 mg matrix patch as compared to 100 picograms from the corresponding Estraderm patch.