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Updated July 02, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.



Photo © 2011 Dawn Stacey

Loestrin is a combination birth control pill that contains ethinyl estradiol and the progestin norethindrone. Loestrin is a little bit different than standard birth control pills because it typically comes in a 21-day pack (however, there are some Loestrin pills that come in packs of 28 pills as well as 21 pills).

In order to effectively use Loestrin, you take one active hormone tablet each day for 21 days (3 weeks). Then, instead of taking a placebo or inactive pill, you take nothing for the next 7 days. You will typically have your withdrawal period during this week. Then you begin your next pack as soon as the week is over.

Loestrin is classified as a monophasic birth control pill because the strength of the hormone does not change throughout the pill cycle. It works like all other combination birth control pills in the ways that it helps to prevent pregnancy.

Loestrin is available in varying strengths:

  • Loestrin 1/20 (this has a lower dose of hormones - 20 mcg ethinyl estradiol and 1.00 mg norethindrone)
  • Loestrin 1.5/30 (this formulation has a slightly higher dose of hormones - 30 mcg of ethinyl estradiol and 1.50 mg norethindrone)
  • Lo Loestrin 1/10 (this has 10 mcg ethinyl estradiol and 1 mg norethindrone)
Based on your past reaction to the pill, and your medical history, your doctor will determine the right formulation for you.

Loestrin 1/20 is often chosen as a first pill option because it is considered a low estrogen dose pill (thus it has less potent effects of estrogen). Because it contains 30–35 mcg estrogen. Loestrin 1.5/30 is categorized as a regular dose birth control pill.

Loestrin contains a high androgenic/low estrogenic profile. Though it may not be the same for everyone, pills with this combination could be helpful for preventing certain side effects or helping ease endometriosis-related pain, moodiness/irritability, severe menstrual cramps and weight gain. However, because Loestrin has high androgenic effects and low estrogen activity, it may be more likely to cause the side effects of unwanted hair growth and acne (but a lot of this depends upon on whether or not you have a predisposition towards producing physiological reactions similar to those produced by male sex hormones).

That being said, the lower estrogen levels may help minimize some of the typical birth control pill side effects. And by using Loestrin, you may benefit from such non-contraceptive benefits as:

When taken as directed, Loestrin is also just as effective as the birth control pill: 92-99.7%. Any woman who is a good candidate for the pill should also be able to take Loestrin.

One Last Important Distinction:

Loestrin is NOT the same as Loestrin Fe, Lo Loestrin FE, or Loestrin 24 Fe (this is the first FDA-approved 24-day oral mini extended cycle contraceptive with 24 active days and only four placebo pills designed for shorter periods). Both of these pill brands also contain 75 mg of ferrous fumarate (a type of iron) in their non-hormonal brown placebo pills.


Jelovsek, R. (2003). "Accurate Answers to Questions About Birth Control Pills." [e-book]. Accessed via private subscription.

Pronunciation: lo/es·trin/
Also Known As:

Loestrin 1/20, Loestrin 1.5/30, LoLoestrin 1/10

Loestrin is available in generic options:
  • Junel (1/20 and 1.5/30)
  • Microgestin (1/20 and 1.5/30)
Common Misspellings: Lo Estrin, Estrin

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