Take the emergency contraceptive pill within the right window for safety and best effectiveness.
How Soon Do You Need to Take the Emergency Contraceptive Pill?
- Take it as soon as possible after sex — the sooner, the better. Effectiveness is highest within the first 24 hours and it should not be taken after 72 hours
- It does not protect 100% of the time and should never replace a regular monthly contraceptive pill
- Take one tablet as soon as you are ready (swallow with water, before or after food)
- If you vomit within 2 hours, take another tablet and check with a pharmacist or doctor to be sure
- Do not use it often (no more than 2 times per cycle) — switch to a regular contraceptive plus condoms afterwards
- If your period is more than 7 days late, or you have severe lower abdominal pain or unusual bleeding, take a pregnancy test and see a doctor
What's on this page?
- How Many Hours Do You Have to Take the Emergency Pill? — Effectiveness Over Time
- When Should You Use the Emergency Pill?
- Can You Still Get Pregnant After Taking the Emergency Pill?
- Does Body Weight Affect How Well the Emergency Pill Works?
- How to Take the Emergency Pill for Best Results
- Side Effects of the Emergency Pill
- What to Do After Taking the Emergency Pill
- Frequently Asked Questions
⚠️ Disclaimer
The information on this page is for general informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment from a qualified doctor or pharmacist. If you have any questions about your symptoms or medication, always consult a doctor or pharmacist first.
How Many Hours Do You Have to Take the Emergency Pill? — Effectiveness Over Time
The single most important rule for the emergency pill is "the sooner, the better" — do not wait until the next morning. If you are ready, take it right away.
Levonorgestrel 1.5 mg is approved by WHO and the FDA for use within 72 hours (3 days) of unprotected sex, but effectiveness drops the longer you wait.
| Time After Sex | Estimated Effectiveness | Urgency Level |
|---|---|---|
| Within 12 hours | Highest (best) | ⚡ Take it as soon as possible |
| Within 24 hours | ~85–95% | 🟢 Still a very good window |
| 24–48 hours | ~80–85% | 🟡 Still effective, but declining |
| 48–72 hours | ~52–75% | 🟠 Effectiveness drops noticeably |
| Over 72 hours | Very low / not recommended | 🔴 See a doctor |
📌 Key statistic: Research from Cleveland Clinic found levonorgestrel to be as much as ~94% effective when taken within the first 24 hours, dropping to only ~58% by the 72-hour mark — showing that every hour of delay significantly lowers protection.
💡 Why does speed matter? The emergency pill works by delaying or preventing ovulation — if the egg has already been released, the pill can no longer prevent pregnancy. The sooner you take it, the better the chance of stopping ovulation in time.
When Should You Use the Emergency Pill?
The emergency pill is a backup option for emergencies only — not a regular method of contraception. Situations where you might consider it include:
| Situation | Details |
|---|---|
| Condom broke or slipped off | The condom tore or came off during sex |
| No protection used | Sex without any contraception |
| Missed daily pills | Missed several days of the daily contraceptive pill in a row |
| Miscalculated the safe period | Misjudged the safe window incorrectly |
| Sexual assault | In cases of sexual assault, also see a doctor |
⚠️ The emergency pill is not an abortion pill — it cannot end an existing pregnancy. Once the egg has implanted in the uterus, the pill has no effect.
Can You Still Get Pregnant After Taking the Emergency Pill?
The short answer: pregnancy is still possible, but the risk is very low if you take it quickly.
A single dose of the emergency pill (levonorgestrel 1.5 mg) can lower the chance of pregnancy by up to ~85–95% when taken within 24 hours, but no emergency contraceptive pill offers 100% protection.
How it works
The emergency pill acts in several ways:
- Delaying or preventing ovulation — its main and most important mechanism
- Thickening cervical mucus — making it harder for sperm to pass through
- Altering the uterine lining — reducing the chance of implantation
Signs you should take a pregnancy test after taking the emergency pill
- Your period is more than 7 days later than usual
- Unusually severe lower abdominal pain
- Abnormal bleeding (which may signal an ectopic pregnancy — a medical emergency)
Does Body Weight Affect How Well the Emergency Pill Works?
This is a question researchers keep studying:
- Research on PubMed found that women with a BMI over 30 may have a higher pregnancy rate after taking levonorgestrel, with the rate rising from ~1.4% (65–75 kg) to ~6% (over 80 kg).
- However, another study from WHO analysing data from 5,812 women found no clear link between body weight/BMI and reduced effectiveness.
- WHO confirms that access to emergency contraception should not be restricted regardless of body weight.
| Body Weight | What to Know |
|---|---|
| Under 70 kg | Normal effectiveness |
| 70–80 kg | May be slightly reduced — still recommended |
| Over 80 kg | Some studies show reduced effectiveness — ask a pharmacist or doctor about other options |
📌 Bottom line: Whatever your body weight, the emergency pill is still worth taking — it is far better than no protection at all. If you are concerned, ask a pharmacist about other options.
How to Take the Emergency Pill for Best Results
📖 Read more details at: How to Take the 1-Tablet Emergency Pill for Best Results
Key steps
- Take one tablet immediately once you are ready — do not wait until morning
- Swallow it whole with plain water — do not crush or chew it
- You can take it before or after food — if you get nauseous easily, taking it after food is recommended
- If you vomit within 2 hours of taking it → you must take another tablet
Emergency Pill: 1-Tablet vs 2-Tablet Regimen
| Detail | 1-Tablet Regimen | 2-Tablet Regimen |
|---|---|---|
| Active ingredient | Levonorgestrel 1.5 mg | Levonorgestrel 0.75 mg × 2 |
| How to take it | Take 1 tablet immediately | Take the first tablet immediately, then the second 12 hours later |
| Effectiveness | Equivalent | Equivalent |
| Advantage | Convenient — done in one tablet | A more affordable option among some brands |
| Available at Intimo Life | Levonorgestrel, Tansy One | Postinor |
📌 Research on PubMed confirms that both regimens are equally effective — choose whichever is more convenient.
Side Effects of the Emergency Pill
📖 Read more about the side effects of every type of contraceptive pill at: Contraceptive Pill Side Effects — What to Expect
Most side effects are mild and go away on their own within 1–2 days:
- Nausea/vomiting — the most common; if you vomit within 2 hours you must take another tablet
- Headache/dizziness
- Breast tenderness
- Fatigue
- Lower abdominal pain
- Irregular period — may come 1–2 weeks earlier or later than usual, or with spotting
| Symptom | Usually Resolves In | See a Doctor If |
|---|---|---|
| Nausea | 1–2 days | Severe vomiting that will not stop |
| Headache | 1–2 days | Unusually severe pain |
| Irregular period | 1–2 cycles | More than 7 days late |
| Lower abdominal pain | 1–2 days | Very severe pain (may signal ectopic pregnancy) |
What to Do After Taking the Emergency Pill
The emergency pill only protects against that one act of sex — it does not protect the next time.
What to do next
- Use condoms every time until you start a regular contraceptive method
- Start or restart a daily contraceptive pill as soon as the next day → read more: Which contraceptive pill brand is right for you?
- Take a pregnancy test if your period is more than 7 days late
- Do not use the emergency pill often — no more than 2 times per menstrual cycle
💡 The emergency pill is not a regular contraceptive — for long-term contraception, a daily pill is a much better choice in terms of effectiveness, side effects and cost → read more: Emergency Pill vs Contraceptive Pill — What's the Difference?
Frequently Asked Questions
Regular use is not recommended, as it can disrupt your cycle and increase side effects. Do not use it more than twice per menstrual cycle. For long-term contraception, switch to a daily contraceptive pill.
No — there is no medical evidence that the emergency pill affects your ability to have children in the future.
Your period may come about a week earlier or later than usual. If it is more than 7 days late, take a pregnancy test.
Light spotting after taking the emergency pill is normal and nothing to worry about. However, if bleeding is unusually heavy or you have severe abdominal pain, see a doctor right away.
The emergency pill cannot end an existing pregnancy, and current evidence has not found it harmful to the fetus. Even so, it is not recommended once you know you are pregnant.
Some medicines can reduce how well the emergency pill works, including anticonvulsants (carbamazepine, phenobarbital), the anti-tuberculosis drug rifampicin, and the herbal supplement St. John's Wort. Always tell your pharmacist about any medicines you are taking.
Yes — levonorgestrel is safe for breastfeeding mothers. Only a very small amount passes into breast milk (a relative infant dose of about 8%), which is within the safe range.
Both are equally effective. The 1-tablet version (1.5 mg) is more convenient since it is done in a single dose, while the 2-tablet version (0.75 mg × 2) requires taking the second tablet 12 hours after the first.
In Thailand, the emergency pill can be bought at pharmacies with no age restriction. The US FDA has also approved it for use at any age.
⚠️ Disclaimer
The information on this page is for general informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment from a qualified doctor or pharmacist. If you have any questions about your symptoms or medication, always consult a doctor or pharmacist first.
References
- Girum T, Wasie A. Return of fertility after discontinuation of contraception: a systematic review and meta-analysis. Contracept Reprod Med. 2018
- NHS — When will my periods come back after I stop taking the pill?
- Mayo Clinic — Getting pregnant after birth control
- ACOG — Fertility Awareness-Based Methods of Family Planning
- WHO — Family Planning/Contraception Methods
- Mikkelsen EM et al. Pre-gravid oral contraceptive use and time to pregnancy. Human Reproduction. 2013