Levonorgestrel is a progestin-only emergency contraceptive pill that prevents unplanned pregnancies following unprotected sex. This synthetic hormone works like the natural progesterone hormone in women's bodies but it has more specific effects. It prevents pregnancy in most cases when women take it within 3 days after unsafe sex. The science behind levonorgestrel is simple. It stops or delays ovulation so no egg gets released. But once ovulation has already happened, the standard dose won't work and doesn't affect implantation. This article explains the uses of levonorgestrel, its dosage, and the precautions you should take.

How Does Levonorgestrel Work?

Levonorgestrel mainly works by stopping or delaying ovulation. It blocks the luteinising hormone (LH) surge that releases eggs from the ovary. It also makes cervical mucus thicker, which makes it harder for sperm to reach the egg. This makes fertilisation nowhere near as likely to happen.

Studies show that levonorgestrel won't affect an embryo that's already implanted or disrupt a pregnancy that's already started. It only works before ovulation happens, which is why it doesn't work as well if you wait too long to take it.

Uses of Levonorgestrel

Levonorgestrel shows up in birth control methods of all types:

• Emergency tablets (Plan B) you can use within 72 hours after unprotected sex

• Regular birth control pills with smaller doses

• Intrauterine devices (IUDs) that last 3-8 years

• Subdermal implants that work for up to 5 years

• Combinations with oestrogen for menopausal hormone therapy

How & When to Take Levonorgestrel?

You should take one 1.5mg tablet as quickly as possible within 72 hours after unprotected sex. You can also take two 0.75mg tablets 12 hours apart. Taking it quickly is vital because it becomes less effective over time.

You should call your doctor if you throw up within two hours of taking the pill - you might need another dose. You can take levonorgestrel with or without food during any part of your menstrual cycle.

What Are the Side Effects of Levonorgestrel?

Common side effects include:

• Menstrual changes - irregular bleeding, spotting, delay

• Nausea 

• Stomach pain 

• Tiredness 

• Headaches 

• Dizziness 

• Tender breasts 

Can We Take Levonorgestrel Daily?

Emergency levonorgestrel pills are safe but aren't meant to be your regular birth control. You shouldn't use high-dose emergency formulations often. Lower-dose versions exist if you need daily birth control. Your doctor can help you find better long-term birth control options that fit your needs.

Precautions 

You need to be extra careful with this medication if you have specific medical conditions. Doctors should be consulted first by people with liver disease, undiagnosed vaginal bleeding, or breast cancer. More importantly, pregnant women should stay away from it since it won't end existing pregnancies.

The medication becomes less effective in people who weigh over 75 kg. Alternative emergency contraceptives might work better if your BMI exceeds 26. Medical guidance becomes necessary for teens under 16 years old.

What If I Missed a Dose?

Missing a dose of regular contraceptive pills with levonorgestrel raises your pregnancy risk. Here's what to do with a missed tablet:

• Take it as soon as you remember

• Take your next pill at the usual time

• Use backup contraception for seven days minimum

What If I Overdose?

Levonorgestrel overdose hasn't shown any serious adverse effects. All the same, large amounts might cause nausea, vomiting, or irregular bleeding. You should see a doctor if you suspect an overdose.

Drug Interactions

These medications can make levonorgestrel less effective:

• Anticonvulsants (phenytoin, carbamazepine)

• Rifampicin and rifabutin

• HIV medications

• St. John's Wort

Dosage for Levonorgestrel

Emergency contraception requires one 1.5mg tablet within 72 hours of unprotected intercourse. You can also take two 0.75mg tablets 12 hours apart.

Daily contraceptive pills usually contain smaller doses between 0.15mg to 0.25mg. Intrauterine devices release levonorgestrel at 14-20 micrograms daily, depending on the product type.

Levonorgestrel vs Ulipristal Acetate 

Understanding the differences between emergency contraception options is crucial at the time you need to choose between them:

Feature	Levonorgestrel	Ulipristal Acetate
Active Ingredient	Synthetic progesterone	Progesterone receptor modulator
Prescription Required	No - available over-the-counter
Effective Timeframe	Up to 3 days (72 hours)	Up to 5 days (120 hours)
Effectiveness	Less effective than ulipristal, especially after 72 hours	2.5x more effective than levonorgestrel when taken within 24 hours
Pregnancy Rates	2.2% when taken within 72 hours	1.4% when taken within 72 hours
Effect on Menstruation	More likely to cause early return of menses	More likely to cause delayed return of menses
BMI Considerations	Less effective for women over 75kg/BMI>25	Remains effective until BMI≥35
Breastfeeding Safety	Safe while breastfeeding	Not recommended during breastfeeding
Starting Hormonal Contraception	Can start the day of or the day after use	Must wait 5 days after use
Side Effects	Headache, nausea, abdominal pain	Headache, abdominal pain

Both medications share similar safety profiles and mild side effects that go away naturally. Ulipristal is a better choice for women with higher body weight since it manages to keep its effectiveness at higher BMI levels.

FAQs

1. What is levonorgestrel used for?

   This emergency contraceptive pill prevents pregnancy after unprotected sex or birth control failures like a broken condom. You should not use it as a regular birth control method. 

2. How does levonorgestrel work to prevent pregnancy?

   We used this medication to prevent or delay ovulation. It also affects the cervical mucus and limits sperm's ability to bind to the egg. The pill can't end an existing pregnancy like abortion pills do. It simply prevents the egg and sperm from meeting.

3. When should I take the Levonorgestrel tablet after unprotected sex?

   Take levonorgestrel within 72 hours (3 days) after unprotected sex to get the best results. Research shows it might work for up to 120 hours (5 days). The pill works better the sooner you take it.

4. What is the correct dosage of levonorgestrel for emergency contraception?

   The standard dosage comes as:

   • A single 1.5 mg tablet taken once

   • Two 0.75 mg tablets taken 12 hours apart

   Both methods work equally well.

5. What are the common side effects of Levonorgestrel tablets?

   Most side effects are mild and go away within 48 hours:

   • Menstrual changes (heavier, lighter or irregular bleeding)

   • Nausea or vomiting

   • Headache

   • Dizziness

   • Breast tenderness

   • Fatigue

   • Abdominal pain

6. Can levonorgestrel delay your next period?

   Your menstrual cycle might change after taking levonorgestrel. Some women get their period a few days earlier or later than expected. You should take a pregnancy test if your period is more than a week late. These changes usually go back to normal by your next cycle.

7. Is levonorgestrel safe to use during breastfeeding?

   Mothers who are nursing can safely use levonorgestrel. Studies show that only tiny amounts get into breast milk, which poses minimal risk to babies. Your doctor might suggest waiting 4 hours after taking the pill before nursing to reduce exposure even further.

8. Can levonorgestrel be taken more than once a month?

   While you can take it multiple times, it's not recommended within the same cycle. The hormone levels in each dose are higher than regular birth control pills. Regular use might cause period irregularities and doesn't work as well as standard birth control methods.

9. What precautions should I follow while taking levonorgestrel?

   Don't take it if you:

   • Are already pregnant

   • Have allergies to any ingredients

   • Experience unexplained vaginal bleeding

   You should tell your doctor about all your ongoing medicines since some can make it less effective

10. Does levonorgestrel protect against sexually transmitted infections (STIs)?

    Levonorgestrel doesn't protect against STIs or HIV. You will need barrier methods like condoms to guard against these infections. Getting an STI test is a good idea if you have had unprotected sex.