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Loestrin vs Lo Loestrin, What’s the Difference? Here’s All You Need to Know

Loestrin and lo Loestrin might confuse a lot of people. Both are oral contraceptives. But, there must be some differences.

So, the question, ‘Loestrin vs lo Loestrin’ is something that pops up into the minds of many.

Loestrin and lo Loestrin both have estrogen and progesterone as their main constituents. However, the concentration of estrogen isn’t the same in both medications. Lo Loestrin contains half the amount of estrogen as Loestrin.

So, what does this mean for you? Which one is better for who? Continue reading to find out.

Table of Content

Loestrin vs Lo Loestrin

Loestrin and Lo Loestrin are both contraceptives. They are both combined oral pill forms of hormonal contraceptives. However, they aren’t exactly the same.

Lo Loestrin, as the name suggests, actually has lower estrogen than Loestrin. For this, there is a slight change in the effect of the drug.


But the side effects of estrogen increase as the dose is increased. However, these differences are subtle. The general indications, contraindications, risks, and safety of these drugs are mostly similar.

Let’s now take a look at hormonal contraceptives and their constituents. And after reading about their effects, we can better understand the differences between Loestrin and Lo Loestrin.

Hormonal Contraceptives

There are many forms of contraceptives available today. Hormonal contraceptives are among the popular ones. You’ve probably already heard about many of these contraceptives.

Hormonal contraceptives use hormones to prevent pregnancy. The ultimate aim of all contraceptives is to prevent pregnancy.

The processes which lead to pregnancy are multiple and complex. So, stopping any one of these can effectively prevent pregnancy. That’s why there are so many types of contraceptives.

Physical contraceptives prevent the passage of sperms. 

So, the sperm and the ovum can’t fuse to form the zygote. However, the physical methods can fail. And they can also cause discomfort and decreased sensation.

That’s why hormonal methods were developed. Hormonal methods prevent the ovum from developing in the first place. They also have additional mechanisms which prevent pregnancy.

Hormonal methods are of different types. Some of them are pills, vaginal rings, transdermal patches, copper T, depot formulation, etc.

Oral pills are also different types depending on the concentration of hormones. Some types are:

  • Combined oral pills
  • Progesterone only pill or mini pill
  • Post-coital pill

Loestrin and Lo Loestrin both are combined oral pills. It means that they have both estrogen and progestin. However, the concentration of these hormones is not very high. And they are effective in contraception.

How Do These Hormones Work for Contraception?

Estrogen and progesterone both act upon the body to prevent contraception. Normally, various hormones have to work together for ovulation to happen. Ovulation is the process through which the egg is developed.

During the regular menstrual cycle, different hormones are released at different times. This is necessary for the development and release of the ovum.

The hormones follicle stimulating hormone (FSH) and Luteinizing hormone (LH) are two important hormones. These are released from the pituitary gland. This is a small gland located underneath the brain. It secretes various important hormones.

Now, the follicle stimulating hormone is essential for follicular development. And Luteinizing hormone is necessary for the release of the ovum from the ovary to the fallopian tubes.

However, these hormones are under negative feedback control. This means that their release is inhibited by other hormones. And those hormones are estrogen and progesterone.

Early in the cycle, the concentration of estrogen and progesterone aren’t very high. So, FSH and LH are secreted. However, in the mid cycle, their concentration rises. This makes the concentrations of FSH and LH drop significantly.

And as you may have understood by now, this negative feedback is what the hormonal pills use. Artificial estrogen and progesterone of Loestrin and Lo Loestrin act on the pituitary and the hypothalamus of the brain. 

This can reduce the secretion of FSH and LH. Estrogen inhibits FSH and progesterone inhibits LH more. So, the ovarian follicle can’t develop and the ovulation can’t take place. This is how the contraceptive action takes place.

What Does That Mean for Loestrin and Lo Loestrin?

Loestrin and Lo Loestrin contain both progesterone and estrogen. So, they can act in the above-mentioned way. However, the concentration is not the same. Now let’s take a look at the individual drugs to see that.


Loestrin contains Ethinylestradiol as estrogen and norethindrone acetate as progesterone. There are a total of  28 tablets in each blister pack. The first 24 of those tablets are white and have ‘WC’ written on one side and 530 on the other. Each of these white tablets contains 1 mg of norethindrone acetate and 20 micrograms of Ethinyl estradiol.

The next 4 tablets are brown. These have “PD 622” written on them. These are iron tablets. They contain 75 mg of ferrous fumarate each.

These don’t have any contraceptive action. Rather, they’re just there to keep count. Blood is lost during menstruation. And iron is an important component of the red blood cells. So, this iron helps to replenish that.

Lo Loestrin

Lo Loestrin is very similar to Loestrin. However, there are some differences.

Lo Loestrin also contains a total of 28 tablets in each blister pack. The first 24 are round blue tablets. These have “WC” written on one side and “421” imprinted on the other. Each tablet contains 1 mg norethindrone acetate. But the Ethinyl estradiol or estrogen is where the difference lies. Lo Loestrin contains only 10 micrograms of Ethinyl estradiol compared to the 20 mcg in Loestrin.

The next 2 tablets are also active, unlike Loestrin. These hexagonal tablets contain 10 micrograms of Ethinyl estradiol each.

The last two tablets are like the iron tablets in Loestrin. These are brown and contain 75 mg of ferrous fumarate.

What Does This Difference Mean?

10 micrograms of Ethinyl estradiol seems to be the difference between these two. But, what does this mean? Logically speaking, the extra estrogen will give a better therapeutic effect in the case of Loestrin. However, if estrogen has any side effects, then Lo Loestrin will have few of them.

But it’s important to keep in mind that the difference between these two is not significant. Rather, those small differences are what we’ll be talking about here.

Therapeutic Response

The efficacy of Loestrin and Lo Loestrin are almost similar. However, there is a difference. The rate of pregnancy is slightly higher in the case of Lo Loestrin.

The efficacy of a contraceptive is measured by the pearl index. The pearl index of Lo Loestrin was around 1.82 in a trial. However, the pearl index of Lo Loestrin was around 2.92 in a clinical trial.

Another thing to consider is that these drugs are widely distributed throughout your body. So, increased BMI would mean that the drug is distributed more. And this can reduce the concentration. Lo Loestrin contains a lower concentration of estrogen. So, if you’re obese, then it’s best to see a doctor before using this.

Side Effects

The most important thing to consider about a contraceptive is its side effects. Loestrin and Lo Loestrin both contain estrogen and progesterone. These are steroid hormones. So, they can act upon various types of cells of the body. Thus, their side effects are varied as well.

Ethinyl estradiol is less in Lo Loestrin. So, the side effects due to estrogen will be less compared to Loestrin. 

These side effects include:

  • Cardiovascular problems: Estrogen increases the risk of several diseases like myocardial infarction, cerebral thrombosis, embolism, etc.
  • Metabolic effects: The lipid profile is changed for the worse by estrogen. The bad cholesterol or LDL is increased. And the good cholesterol or HDL is decreased.
  • This also increases the risk of cancer.
  • The chance of liver disorders like hepatocellular adenoma, gall bladder disease, etc. also increases.
  • Estrogen can be excreted in breast milk, so it’s best to avoid it during pregnancy.
  • Some common unwanted effects are also present which include:

These side effects can happen with both Loestrin and Lo Loestrin. However, the concentrations of estrogen aren’t very high in these drugs. So, you can talk to your physician if you’re worried about these effects.

Lo Loestrin was developed with very low estrogen for these side effects. So, considering the side effects, Lo Loestrin is perfect.


What kind of pill is Loestrin?

Answer: Loestrin is a combined type of oral contraceptive pill. It’s called combined because it contains both estrogen and progesterone.

Do you gain weight on Lo Loestrin?

Answer: Lo Loestrin contains a very small amount of estrogen. And one of the side-effects of estrogen is weight gain. So, it is possible to gain weight on Lo Loestrin. However, the amount of estrogen is less compared to most other contraceptive pills.

What are the benefits of Lo Loestrin?

Answer: Lo Loestrin contains a very small amount of estrogen, only 10 mcg per tablet. So, the main benefit is that the side effects are less compared to other hormonal pills.


‘Loestrin vs Lo Loestrin’ can be quite confusing. But the differences between these two aren’t many. Loestrin has slightly higher efficacy than Lo Loestrin. However, the side effects of Lo Loestrin are less than that of Loestrin as the amount of estrogen hormone is less.

You can consult a doctor before using any of it. He will certainly prescribe the one best for you.

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