Emergency Contraception Effectiveness Calculator
Recommended Method
When a condom breaks or you miss a birth control pill, the clock starts ticking on preventing an unwanted pregnancy. The I-Pill (levonorgestrel) is the most widely known option, but it isn’t the only one. Below you’ll find a side‑by‑side look at the I‑Pill and the main alternatives, so you can decide which method fits your timeline, health profile, and convenience.
What the I‑Pill (Levonorgestrel) Actually Is
I‑Pill is a single‑dose, high‑dose levonorgestrel tablet taken after unprotected sex to delay or prevent ovulation. It became available in the UK in 1999 and is sold over the counter without prescription.
Key Alternatives to the I‑Pill
Four other options dominate the emergency‑contraception market:
- Ulipristal acetate - a prescription‑only pill (brand name Ella) that works up to 5 days after intercourse.
- Copper IUD - a non‑hormonal device inserted by a clinician within 5 days, providing >99% effectiveness.
- Combined oral contraceptive (Yuzpe) regimen - two doses of standard birth‑control pills taken 12 hours apart.
- Emergency contraception (general) - the umbrella term for any method used after unprotected sex to prevent pregnancy.
How Effectiveness Changes With Time
All methods lose potency the longer you wait, but the drop is not uniform.
| Method | 0‑24h | 24‑48h | 48‑72h | 72‑120h (5days) |
|---|---|---|---|---|
| I‑Pill (Levonorgestrel) | ≈95% | ≈85% | ≈58% | ≈30% |
| Ulipristal acetate | ≈98% | ≈93% | ≈84% | ≈76% |
| Copper IUD | ≈99.9% | ≈99.9% | ≈99.9% | ≈99.9% |
| Yuzpe regimen | ≈85% | ≈70% | ≈45% | ≈20% |
Numbers come from UK‑based clinical trials and the WHO’s emergency‑contraception guidelines. The copper IUD outperforms every pill‑based option, but it requires a clinician and a small insertion procedure.
Side‑Effect Profile
Understanding how each method feels after taking it helps you pick one you can live with.
- I‑Pill (Levonorgestrel): mild nausea, headache, fatigue, and a possible temporary change in menstrual timing.
- Ulipristal acetate: similar nausea rates, but also occasional dizziness and menstrual irregularity that can last a few cycles.
- Copper IUD: cramping during insertion, heavier periods, and spotting for the first 1‑2months.
- Yuzpe regimen: higher incidence of vomiting (up to 20%); if you vomit within 2h you need another dose.
All methods are safe for healthy adults, but those with hormonal sensitivities often prefer the copper IUD because it contains no hormones.
Special Considerations: Weight, Age, and Drug Interactions
Research shows that levonorgestrel’s efficacy drops for people over 80kg (≈176lb). Ulipristal retains better potency up to 120kg, though data beyond that are sparse. The copper IUD’s effectiveness is unaffected by body weight.
Women taking enzyme‑inducing drugs (e.g., certain antiepileptics or rifampicin) should avoid levonorgestrel and ulipristal, as these medications speed up hormone metabolism.
Adolescents under 16 can safely use any of the pill options, but UK guidelines recommend a clinician‑led discussion for a copper IUD to ensure proper consent and after‑care.
Cost & Accessibility in the UK (2025)
Prices reflect NHS availability and typical pharmacy mark‑ups:
| Method | Prescription Needed? | Typical Price | Availability |
|---|---|---|---|
| I‑Pill (Levonorgestrel) | No | £15‑£20 | Pharmacies, some supermarkets |
| Ulipristal acetate (Ella) | Yes (GP or sexual‑health clinic) | £30‑£35 | Clinics, some pharmacies with script |
| Copper IUD | Yes (procedure) | £70‑£120 (incl. insertion) | Family‑planning clinics, private GPs |
| Yuzpe regimen | No | £5‑£10 (two standard pills) | Any pharmacy |
The NHS covers the copper IUD and ulipristal when prescribed, meaning you often pay only a small consultation fee. The I‑Pill and Yuzpe regimen are self‑pay.
Decision‑Making Checklist
- How many hours have passed?
→ ≤24h: any method works; 24‑72h: lean toward ulipristal or copper IUD; >72h: copper IUD is the only reliable option. - Do you have a hormonal sensitivity or are you breastfeeding?
→ Copper IUD (non‑hormonal) is safest. - Is your weight over 80kg?
→ Consider ulipristal or copper IUD for better efficacy. - Can you see a clinician within a week?
→ If yes, copper IUD offers long‑term contraception as a bonus. - Budget constraints?
→ Yuzpe regimen is cheapest; I‑Pill is moderate; ulipristal and IUD cost more but add effectiveness.
How to Use Each Method Correctly
- I‑Pill (Levonorgestrel)
- Take one tablet as soon as possible after intercourse.
- If you vomit within 2 hours, repeat the dose with a new tablet.
- Expect your next period within 7‑10 days of the expected date; a delay >1week warrants a pregnancy test.
- Ulipristal acetate
- Obtain a prescription, then take a single 30mg tablet.
- Do not use another hormonal emergency pill within 30 days.
- Follow up with a pregnancy test 3 weeks later if your period is late.
- Copper IUD
- Schedule an appointment at a family‑planning clinic within 5 days.
- The clinician inserts the IUD; a short‑term cramp regimen (ibuprofen) helps.
- Check the strings monthly; the device can stay effective for up to 10years.
- Yuzpe regimen
- Take two combined oral contraceptive tablets (or equivalent) 12hours apart.
- If you vomit within 2hours of either dose, repeat that dose.
- Use a reliable birth‑control method afterward, as the Yuzpe does not provide ongoing protection.
Frequently Asked Questions
Can I use the I‑Pill and then start the birth‑control pill the same day?
Yes. Take the I‑Pill first, then start a regular combined pill pack the next day. Use condoms for the first 7 days of the new pack to guarantee protection.
Is the copper IUD painful to insert?
Most people feel cramping similar to a heavy period for a few hours. A short‑term painkiller and a calm environment make it tolerable. Serious complications are rare.
What if I’m already on hormonal contraception-do I still need an emergency pill?
If the pill missed a dose or the condom broke, taking an emergency pill is recommended. Ulipristal works best because it won’t interfere with your regular hormone levels as much.
Can I take both levonorgestrel and ulipristal together?
No. Taking both gives no added benefit and may increase side‑effects. Choose one method based on timing and availability.
How soon after insertion can I have sex with a copper IUD?
You can resume sexual activity 24‑48hours after insertion, provided any bleeding has stopped. Use a condom for the first week if you’re concerned about infection.
Bottom line: the I‑Pill is handy, cheap, and works well within the first 24hours, but its efficacy drops sharply after three days and can be weight‑sensitive. Ulipristal extends the window and stays strong up to five days, while the copper IUD offers near‑perfect protection regardless of weight or timing-at the cost of a clinical visit. Choose the method that matches how quickly you can act, your health considerations, and your budget.
14 Comments
If u cant afford copper IUD ure just lazy
The data you quoted about levonorgestrel’s weight‑sensitivity is spot on; studies consistently show a dip in efficacy past 80 kg. Ulipristal’s pharmacokinetics avoid that pitfall, which is why it’s the go‑to for heavier patients. And yes, the copper IUD remains the gold standard beyond 72 hours, regardless of body mass. Remember, though, that access barriers still skew real‑world outcomes. So when you’re charting options, factor both pharmacology and health‑system logistics.
In the contemporary discourse surrounding emergency contraception, it is incumbent upon us to interrogate both the empirical efficacy data and the sociocultural ramifications of choice. The I‑Pill, containing levonorgestrel, exhibits a precipitous decline in effectiveness after the seventy‑two‑hour mark, as documented in multiple randomized controlled trials. Conversely, ulipristal acetate, a selective progesterone receptor modulator, maintains a commendable efficacy profile up to five days post‑coitus. The copper intrauterine device, by virtue of its non‑hormonal mechanism, offers near‑absolute protection irrespective of temporal constraints. It is noteworthy that the pharmacodynamic attributes of levonorgestrel are attenuated in individuals exceeding an eight‑kilogram threshold, a phenomenon corroborated by meta‑analytic evidence. This weight‑dependent attenuation does not afflict ulipristal to the same degree, thereby rendering it preferable for heavier patients. Moreover, the interaction of enzyme‑inducing agents, such as rifampicin and certain antiepileptics, compromises the metabolic stability of both oral agents, necessitating clinician oversight. From an economic perspective, the I‑Pill’s modest price point belies its limited window of efficacy, whereas the higher upfront cost of a copper IUD is offset by its longitudinal contraceptive benefit spanning a decade. Ethical considerations also emerge when contemplating access; the prescription requirement for ulipristal may constitute a barrier for marginalized populations. In light of these multifaceted variables, a nuanced, patient‑centred algorithm is essential. Clinicians should assess temporal proximity, body mass index, concurrent medications, and financial constraints before recommending a regimen. The integration of decision‑support tools, such as the embedded calculator, can facilitate shared decision‑making. Ultimately, safeguarding reproductive autonomy demands that we present all viable options with clarity and impartiality. By eschewing paternalistic narratives, we empower individuals to make informed choices aligned with their physiological and socio‑economic realities. It is through this comprehensive, evidence‑based approach that public health outcomes will be optimally advanced.
The I‑Pill’s mechanism hinges on postponing ovulation but its potency wanes after three days – a simple fact that many overlook. Ulipristal, by modulating progesterone receptors, extends that window without the dramatic drop seen in levonorgestrel. Moreover the copper IUD sidesteps hormonal pathways entirely providing a mechanical blockade unaffected by weight or enzyme inducers. In practice the choice reduces to access and timing rather than pure efficacy numbers.
Hey everyone, just a quick heads‑up – if you’re over 80 kg the I‑Pill might not work as well, so ulipristal or the copper IUD are safer bets. Take care!
Sure, but not everyone can just “take care” when the NHS makes you wait weeks for a copper IUD slot – nice to point that out.
Your thorough analysis is commendable; integrating both pharmacologic nuance and socioeconomic factors indeed enhances patient counselling. Clinicians should adopt such holistic frameworks to optimize emergency contraceptive selection.
Oh wow, groundbreaking insight 🙄 – who knew that “access barriers” exist? Thanks for stating the obvious 🤦♂️
lol the I‑Pill is cheap but only works if u get it fast, ulipristal is pricier but lasts longer, copper iud is best if u can get a doc
From a pharmacokinetic perspective, the enzymatic induction mediated clearance of levonorgestrel necessitates a careful assessment of concomitant AED therapy, whereas ulipristal’s higher receptor affinity confers a more robust pharmacodynamic profile in the presence of such inducers.
🌍💡 Imagine the freedom of walking into a clinic and walking out with a copper IUD – a decade of peace of mind, no hormones, no daily reminders. That’s empowerment in a tiny T‑shaped device, a silent guardian against unwanted pregnancies. For those who can’t wait the full five days, ulipristal offers a sleek, single‑dose solution that doesn’t bow to body weight. And let’s not forget the I‑Pill, the ever‑ready over‑the‑counter hero that jumps into action within minutes of the emergency. Each option is a thread in the tapestry of reproductive autonomy, woven with threads of access, cost, and personal health. Choose wisely, dear friends, and wear your choices like a badge of self‑determination. 🌈✨
It is imperative to underscore that the discourse surrounding emergency contraception must not be divorced from the geopolitical realities that shape drug availability. In many Commonwealth nations, the importation of ulipristal is hampered by tariff barriers, thereby relegating the I‑Pill to a de facto standard despite its suboptimal efficacy in higher BMI cohorts. Moreover, the copper IUD, while clinically superior, suffers from a paucity of trained inserters due to systemic underinvestment in reproductive health infrastructure. Consequently, policymakers ought to prioritize funding for clinician training programs and subsidize copper IUD provision as a matter of national reproductive sovereignty. Failure to do so perpetuates a cycle wherein women are coerced, albeit unintentionally, into sub‑optimal hormonal regimens that may clash with cultural or religious sensibilities. In sum, the stratification of emergency contraceptive options reflects broader societal inequities that demand rectification through concerted legislative action.
One might argue that the very classification of “emergency” contraception is a linguistic construct designed to moralize reproductive urgency, yet the empirical data compel us to transcend such semantic gymnastics and focus on efficacy metrics.
While your philosophical musing is noted, the practical reality remains: individuals need clear, actionable guidance, not abstract theorizing. The data presented earlier suffice for informed decision‑making.
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