Emergency contraception is an essential option for preventing unintended pregnancy after unprotected sex or contraceptive failure, but its effectiveness depends heavily on timing. Many people assume that all emergency contraception works in the same way regardless of when it is taken, yet this is not the case. Delays of even a day can significantly reduce how well certain options work, which is why understanding time limits is so important.
Emergency contraception is designed to reduce the risk of pregnancy after unprotected sex, missed contraception, or contraceptive failure such as a split condom. It works primarily by delaying or preventing ovulation, which means it must be taken before an egg is released. Because ovulation timing varies between individuals and cycles, it is often difficult to know exactly when ovulation may occur.
It is important to understand that emergency contraception does not terminate an existing pregnancy and will not be effective once implantation has occurred. It should also not be used as a regular method of contraception. Instead, it acts as a backup option when something has gone wrong, making prompt access and correct choice especially important.
The effectiveness of emergency contraception decreases as time passes after unprotected sex. Hormonal emergency contraception works by interfering with the hormonal signals that trigger ovulation. Once ovulation has already happened, these tablets are no longer able to prevent pregnancy.
Timing matters for several reasons:
Acting quickly improves the chances of success and ensures that the most effective option remains available.
In the UK, there are two main types of oral emergency contraception tablets. Both are safe and effective when used correctly, but they differ in how long after unprotected sex they can be taken and how close to ovulation they remain effective. Understanding these differences can help you choose the right option based on your situation.
Levonorgestrel based emergency contraception is effective when taken within 72 hours of unprotected sex. Its effectiveness is highest when taken as soon as possible, particularly within the first 24 hours. After this point, its ability to delay ovulation gradually decreases.
This option is widely used and suitable for many people, but it may be less effective if ovulation is approaching or if more than a day has passed since unprotected sex. For this reason, speed of access is especially important with levonorgestrel.
Ulipristal acetate can be taken up to 120 hours after unprotected sex. It remains effective closer to ovulation than levonorgestrel, making it a useful option when more time has passed. This extended window can be reassuring for those who are unsure exactly when unprotected sex occurred.
Due to its different hormonal action, ulipristal acetate may not be appropriate for all patients and can interfere with existing hormonal contraception. Professional guidance helps ensure it is used correctly and safely.
Are you unsure which type of emergency contraception is right for you? Start an online consultation today to speak with our expert team who can help you make an informed decision.
This comparison highlights the major differences between the two main emergency contraception options available. It helps clarify how timing, effectiveness, and suitability can vary between them.
| Feature | Levonorgestrel | Ulipristal Acetate |
|---|---|---|
| Time window | Up to 72 hours | Up to 120 hours |
| Effectiveness over time | Reduces after 24 hours | Maintains effectiveness longer |
| Hormonal interaction | Limited | May interact with hormonal contraception |
Emergency contraception should be taken as soon as possible after unprotected sex. Waiting to see if it is needed or delaying access can reduce effectiveness and increase stress. Even if you are unsure which option is right, seeking advice early keeps more choices available.
Important factors to consider include:
As these factors differ between individuals, professional assessment helps identify the safest and most effective option.
Misunderstandings about emergency contraception can lead to delays or incorrect use. Some people believe all options work equally well at any time, while others assume waiting a day or two does not matter. These misconceptions can reduce effectiveness and increase anxiety.
Clear, accurate information helps people act quickly and confidently, improving outcomes and reducing unnecessary worry.
At The Care Pharmacy, we provide discreet, regulated access to emergency contraception supported by professional guidance. Our online consultation process allows suitability to be assessed quickly, helping patients receive treatment without unnecessary delays.
If you are unsure which option is right or need advice urgently, get in touch with our team for guidance or start an online consultation form to receive personalised support.
Timing is one of the most important factors when using emergency contraception. Acting quickly and choosing the right option can significantly reduce the risk of unintended pregnancy.
For trusted, regulated emergency contraception support, start an online consultation or get in touch with The Care Pharmacy to discuss your options with confidence and professional care.
This blog was written in collaboration with Pharmacy Mentor.
Medically reviewed by
Superintendent Pharmacist
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