Medical Health Encyclopedia

Progestins alone may be helpful and are the oldest drugs used for endometriosis. Progestins can prevent ovulation and reduce the risk for endometriosis in the following ways:

• They block luteinizing hormone (LH), one of the reproductive hormones important in ovulation.
• They change the lining of the uterus and eventually cause it to atrophy.
• One study reported that progestins provide temporary pain relief equivalent to the more powerful hormone drugs, such as danazol or a GnRH agonist. Some experts recommend them as the first choice for women with endometriosis who do not want to become pregnant. Progestins given during the luteal phase do not appear to be beneficial. (This is the premenstrual phase, which is 14 days before a period.)

Specific Progestins. Progestins are available in pill or injectable form, or as a progestin-releasing intrauterine device (IUD). Medroxyprogesterone (Depo-Provera), which is administered by injection typically every three months, is one of the standard progestins used. A new formulation, Depo-subQ Provera 104, was approved in 2005. Oral progestins include norethindrone (Micronor, Aygestin, Norlutate). Norethindrone is also known as norethisterone.

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Progestin-releasing IUDs can be very helpful for many women with endometriosis, particularly an advanced version called the levonorgestrel-releasing intrauterine system, or LNG-IUS (Mirena). Studies are suggesting that the LNG-IUS reduces endometrial cell proliferation and increases cell self-destruction. Progestin released by the IUD mainly affects the uterus and cervix and causes fewer widespread side effects than other forms of progestins. The LNG-IUS has proved effective for heavy bleeding (menorrhagia) and studies are indicating that it is also effective in controlling the symptoms of minimal to moderate endometriosis.

Click the icon to see an image of an IUD.