A Comprehensive Guide to Emergency Contraceptive Pills: ellaOne and Levonorgestrel
Emergency Contraceptive Pills, also known as “morning-after pills”, are medications used to prevent pregnancy after unprotected intercourse or a contraceptive failure (such as a condom breakage or missing regular contraceptive pills). In the UK, there are two types of morning after pill: Levonorgestrel (branded as Levonelle) and ellaOne. Both these morning after pills work in a similar way and are really effective at preventing pregnancy when they’re taken at the right time. However, there are some differences between the two, which might be important for certain women.
How Emergency Contraceptive Pills Work
ECPs work in various ways to prevent pregnancy:
- Preventing Ovulation: They try to stop the ovaries from releasing eggs.
- Preventing Fertilization: If an egg has already been released, ECPs prevent the sperm from fertilizing the egg.
- Preventing Implantation: If fertilization has occurred, they prevent the fertilized egg from implanting onto the uterus wall.
- Thickening the Cervical Mucous: This makes it harder for sperm cells to penetrate and reach the egg.
Key Facts and Differences
When choosing between treatments, consider the following key facts about ellaOne:
- Must be taken within five days of unprotected sex
- Contains ulipristal acetate, which affects how progesterone works and stops or delays ovulation
- Shouldn’t be taken when breastfeeding
- Can be used more than once in the same cycle
- Second tablet required if you vomit within three hours of taking ellaOne
In comparison, here are the key facts about levonorgestrel/Levonelle:
- Must be taken within 72 hours (three days) of unprotected sex
- Contains levonorgestrel, a synthetic version of progesterone, which is thought to stop or delay ovulation
- Safe to take when breastfeeding
- Can be used more than once in the same cycle
- Second tablet required if you vomit within two hours of taking levonorgestrel
Effectiveness and Weight Considerations
It’s generally accepted that ellaOne is more effective at preventing pregnancy than Levonorgestrel. Clinical studies have found that ellaOne is 2.5x more effective than levonelle (the branded version of levonorgestrel) when taken within 24 hours. However, the most effective form of emergency contraception is the emergency IUD or coil.
Weight can also impact efficacy. Levonorgestrel is thought to be less effective in women who weigh over 70kg or who have a BMI over 26. The recommendation for women over this weight or BMI may be to take two levonorgestrel tablets, or one ellaOne tablet.
Dosage and Administration
Levonorgestrel tablets, 0.75 mg is a progestin-only emergency contraceptive indicated for prevention of pregnancy. To obtain optimal efficacy, the first tablet should be taken as soon as possible within 72 hours of intercourse. The second tablet should be taken 12 hours later. Efficacy is better if the tablet is taken as soon as possible after unprotected intercourse.
Who Should and Should Not Take the Pill
Most women can use the morning after pill. For instance, the morning after pill can be used by trans people who were assigned female at birth. If you have the potential to become pregnant, have ovaries and a womb you can use ellaOne or levonorgestrel.
Regarding breastfeeding, the effects of ellaOne during breastfeeding aren’t known so it’s advised that women who are breastfeeding use levonorgestrel (generic Levonelle). Levonelle is safe to take while breastfeeding, although small amounts can pass into your breastmilk; it’s not thought to be harmful to your baby.
Drug Interactions
Certain medications interact negatively with the morning after pill. This is why it’s important to mention if you’re taking any specific medications when you get the morning after pill. For women taking these kinds of medications, ellaOne can’t be prescribed, but levonorgestrel may be given – usually in a higher dose than normal.
| Condition | Medication |
|---|---|
| Epilepsy | primidone, phenobarbital, phenytoin, fosphenytoine, carbamazepine, oxcarbazepine and barbiturates |
| Tuberculosis | rifampicin, rifabutin |
| HIV | ritonavir, efavirenz, nevirapine |
| Fungal infections | Griseofulvin |
| Various health conditions | St John's wort (Hypericum perforatum) |
Side Effects and Precautions
Emergency contraceptive pills generally have minimal side effects, which may include nausea, vomiting, and headaches. The most common adverse reactions (≥10%) in clinical trials included:
- Menstrual changes (26%)
- Nausea (23%)
- Abdominal pain (18%)
- Fatigue (17%)
- Headache (17%)
- Dizziness (11%)
- Breast tenderness (11%)
Important things to remember include that ECPs should not be used as a routine contraceptive method. You may experience disturbances in your menstrual cycle after taking ECPs. While ECPs are effective, they do not guarantee complete prevention of pregnancy. If menses is delayed beyond 1 week, pregnancy should be considered.