Home Medicines Levonorgestrel: effect, areas of application, side effects

Levonorgestrel: effect, areas of application, side effects

by Josephine Andrews
Published: Last Updated on 125 views

Levonorgestrel is an artificially produced corpus luteum hormone that, depending on the dosage, is taken as a contraceptive pill or as the so-called “morning after pill”. A “spiral” with levonorgestrel is also available as a mechanical contraceptive. Here you can read more about the effects and use of levonorgestrel – as a morning-after pill and as a contraceptive pill or contraceptive spiral.

This is how levonorgestrel works

As a corpus luteum hormone (gestagen), levonorgestrel influences the body’s own regulation of the menstrual cycle. This can be roughly divided into two sections, each lasting about two weeks: the follicular phase and the luteal phase.

The follicular phase begins on the first day of menstrual bleeding ( menstruation ). The lining of the womb that was built up in the previous cycle is now expelled along with the unfertilized egg. At the same time, a new ovarian follicle containing an egg cell is developing in one of the ovaries (sometimes both).

Ovulation heralds the second half of the cycle, the luteal phase. The ovary or the ovarian follicle that has matured in it releases the egg cell, which is then taken up by the fallopian tube . She is capable of fertilization for about 12 to 24 hours. The now empty follicle in the ovary transforms into the corpus luteum and starts producing the body’s own corpus luteum hormone progesterone .

This suppresses the development of further follicles in the ovaries and prepares the uterine lining for the eventual implantation of the fertilized egg. Later, the placenta takes over the production of progesterone and thus ensures that the pregnancy is maintained.

If, on the other hand, no fertilization takes place, the corpus luteum shrinks, which means that no more progesterone is produced. With the next menstrual period, the thickened lining of the uterus is shed and excreted together with the non-fertilized egg.

Levonorgestrel as a contraceptive pill

By taking a synthetic progesterone analogue such as levonorgestrel, the body is fooled into thinking that it is pregnant and the pituitary gland ( pituitary gland ), which controls the female cycle centrally, signals that no more ovulation and no new menstrual bleeding should be initiated.

Levonorgestrel also makes the secretions of the cervix thicker, which means that sperm cannot get into the uterus as easily. Natural progesterone could not be used for this purpose because it would be quickly broken down in the liver after ingestion.

For contraception, levonorgestrel is taken alone or in combination with other hormones (such as ethinylestradiol), adapted to the cycle, in phases or permanently as a ” pill “.

Levonorgestrel as the “morning after pill”

Levonorgestrel is also approved in higher doses as the “morning after pill”. It can drastically reduce the chance of pregnancy for up to three days (72 hours) after unprotected sex.

It is not known exactly how this effect comes about. However, levonorgestrel is thought to prevent the possibly fertilized egg from implanting, preventing ovulation, or interfering with egg transport. However, if the egg cell has already implanted itself, taking levonorgestrel has no effect. The “morning after pill” does not lead to an abortion.

intake, degradation and excretion

After ingestion, levonorgestrel is completely absorbed in the intestine and reaches the highest levels in the blood after three hours. If the active ingredient is taken only once (as with the “morning after pill”), half of the active ingredient is excreted after about two days.

When taken repeatedly (as a contraceptive pill), the active substance accumulates in the body and its excretion is delayed.

Levonorgestrel is broken down in the liver and about half is excreted in the urine and half in the stool.

When is levonorgestrel used?

Levonorgestrel is approved for contraception as a single active ingredient (as the so-called ” mini- pill “) or in combination with an estrogen (usually ethinyl estradiol).

The progestogen levonorgestrel is used as the “morning after pill” in higher doses for emergency contraception up to three days (72 hours) after unprotected sexual intercourse.

How levonorgestrel is used

For contraception, a combined pill with levonorgestrel and an estrogen is usually used. It is taken for the first 21 days of the cycle (start: day 1 of the menstrual period), at the same time every day if possible.

This is followed by a seven-day break before starting again with a new pack of pills. In the case of some preparations, in addition to the 21 hormone-containing tablets, a pack also contains seven placebo tablets without active ingredients, so that you do not get out of the rhythm of daily intake.

The mini-pill , which contains only levonorgestrel, is taken continuously. With her, women have to pay even more attention to a regular intake time. If you forget to take a pill by more than three hours, contraceptive protection is no longer guaranteed for at least seven days.

The forgotten tablet with levonorgestrel should then be taken as soon as possible, even if this means that two tablets have to be taken at the same time because the time for the next dose has already come.

Caution: This only applies to the mini-pill as an exception – with other contraceptive pills, two tablets must never be taken at the same time!

An intrauterine device ( hormone coil ) with levonorgestrel can remain in the uterus for up to five years. It is therefore primarily suitable for long-term contraception.

Levonorgestrel as an emergency contraceptive (” morning- after pill “) must be taken as soon as possible after unprotected sexual intercourse, but no later than 72 hours:

After the consultation with the doctor or in the pharmacy, the tablet is usually taken on the spot, which is also intended to prevent the tablet from being bought “in advance”. If vomiting occurs within three hours after ingestion, an “morning after pill” must be taken to ensure the effect.

What are the side effects of levonorgestrel?

The side effects of levonorgestrel are dose dependent. They occur more frequently in higher doses, most notably with the “morning after pill”.

More than ten percent of the women treated experience headaches, nausea, pain in the lower abdomen, vaginal bleeding and fatigue.

In addition, dizziness, diarrhea, vomiting, delayed menstrual bleeding, bleeding between periods and a feeling of tenderness in the breasts can also occur when taking a high-dose pill containing levonorgestrel.

The side effects when taken as a contraceptive pill are usually rarer and less pronounced.

The tolerability of the “morning after pill” can be improved by eating a small meal (e.g. a sandwich) at the same time.

What should be considered when using levonorgestrel?


Levonorgestrel as the “morning after pill” must not be taken if:

  • Hypersensitivity to the active ingredient or any of the other ingredients of the drug

Levonorgestrel as a contraceptive pill must also not be taken in the following cases:

  • known or suspected pregnancy
  • existing thromboembolic diseases (such as deep vein thrombosis, pulmonary embolism )
  • Previous or existing arterial and cardiovascular diseases (such as heart attack, stroke)
  • Diabetes with vascular changes
  • severe liver dysfunction or liver tumors
  • Cancer diseases when they are influenced by sex hormones
  • unexplained vaginal bleeding


The combination with other active ingredients that are broken down via the same liver enzyme system (cytochrome P450 3A4) can cause levonorgestrel to be broken down more quickly and therefore not or not sufficiently effective.

Examples of such drugs include anti-epileptic and anti-seizure drugs (such as phenobarbital, phenytoin, carbamazepine, topiramate), anti-infective drugs (such as rifampicin, efavirenz, ritonavir, griseofulvin), and the herbal antidepressant St. John’s Wort.

Taking levonorgestrel can increase the risk of heart attacks and strokes in patients with coagulation disorders and in smokers.

age restriction

There is no indication for levonorgestrel before menarche (the first menstrual period in a woman’s life).

pregnancy and breast feeding period

Pregnant women should not take hormone preparations such as the pill (levonorgestrel alone or together with an estrogen), but also the “morning-after pill”. Accidental intake of a contraceptive pill or “morning after pill” during pregnancy does not require any further diagnostics.

Pure gestagen preparations are among the means of choice for hormonal contraception during breastfeeding . They do not require breastfeeding restrictions. Levonorgestrel pills should not be started before six to eight weeks after delivery. The same time frame is recommended for inserting the IUS.

How to get Levonorgestrel medication

The “morning after pill” with levonorgestrel does not require a prescription in Germany, Austria and Switzerland, as well as in many other European countries, and can be purchased in pharmacies without a prescription after thorough consultation.

The contraceptive pill with levonorgestrel, on the other hand, requires a prescription. The same applies to the hormone spiral.

Since when is levonorgestrel known?

The first man-made progestin used as a contraceptive, norethisterone, was developed by the Austrian chemist Carl Djerassi in the early 1950s. The active ingredient was later developed into levonorgestrel.

The contraceptive is not patent-protected, which is why numerous pharmaceutical companies sell preparations with the active ingredient levonorgestrel.

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