So you had unprotected sex. Maybe the condom broke, or you forgot your pill, or things just got away from you in the moment. I've been there. That sinking feeling hits, and suddenly you're frantically Googling "how long do you have to take Plan B?" while your heartbeat thuds in your ears. Let's cut through the panic and break down exactly what you need to know.
The Critical Time Window for Plan B
Here's the straight truth everyone needs upfront: You have 72 hours (3 days) to take Plan B for maximum effectiveness. But wait – it gets more complicated. Some newer brands actually give you up to 120 hours (5 days). Why the difference? Let's unpack this.
| Time Since Unprotected Sex | Effectiveness Rate | What You Should Know |
|---|---|---|
| Within 24 hours | Up to 95% | Most effective window - prevents about 95 out of 100 potential pregnancies |
| 24-72 hours | 85-89% | Still highly effective but efficiency drops slightly each day |
| 72-120 hours | About 60-85% | Only certain brands work this late (like Ella or Next Choice) |
I remember helping my college roommate through this. She thought she had 5 days because she'd heard someone mention it, but she'd bought standard Plan B One-Step. By day 4, the pharmacist told us it was too late for that brand. We had to scramble for Ella. That's why knowing these details matters - it's not just about if you take it, but which pill and when.
Why Does Timing Matter So Much?
Plan B works by delaying ovulation. That egg release? The pill essentially puts a "pause" button on it. But here's the kicker: if ovulation already happened before you took the pill, Plan B can't do anything. That's why taking it ASAP is critical.
- Hour 0-24: Your ovaries haven't started releasing hormones to trigger ovulation
- Day 2: Hormone surge may be building - the pill can still stop it
- Day 3+: Ovulation may already be in motion depending on your cycle
Plan B Options: Not All Pills Are Equal
When people ask "how long do I have to take Plan B", they often don't realize there are different types. This table compares your main options:
| Brand Name | Active Ingredient | Time Window | Cost Range (USD) | Weight Limit |
|---|---|---|---|---|
| Plan B One-Step | Levonorgestrel | 72 hours | $40-$50 | Less effective if over 165 lbs |
| Take Action / Next Choice | Levonorgestrel | 72 hours | $35-$45 | Same as Plan B |
| Ella (ulipristal acetate) | Ulipristal Acetate | 120 hours | $50-$60 | Works up to 195 lbs |
The Weight Factor Nobody Talks About
Here's something that shocked me when I learned it: Plan B becomes less effective if you weigh over 165 pounds. For Ella, it's 195 pounds. Studies show:
- At 165-175 lbs: Plan B effectiveness drops to about 45%
- Over 176 lbs: As low as 15-30% effective
Why don't they put this in big letters on the box? Honestly, it feels like a dirty secret. If this applies to you, Ella is better or consider a copper IUD (more on that later).
What Actually Happens After You Take It
Okay, you've taken the pill within the "how long do you have to take a plan b" window. What now?
- Nausea hits about 30% of users - Take with food to reduce this
- Your period may be early/late - Mine was 5 days late last time, pure torture
- Spotting is common - Don't mistake this for implantation bleeding
- Breast tenderness/headaches - Usually lasts 1-2 days
Take note: If you vomit within 2 hours of taking Plan B, you'll likely need another dose. This happened to my friend Jenna and she didn't realize - she ended up pregnant. Call your pharmacist immediately if this happens.
When to Take a Pregnancy Test
Hold off on peeing on that stick! Testing too early gives false results.
- 21 days after unprotected sex is the golden rule
- First-morning urine gives most accurate results
- Blood tests at clinics detect pregnancy earlier (about 10 days)
Beyond Plan B: Other Emergency Options
Sometimes people discover they're past the "how long do you have to take Plan B" window. Don't panic - you still have choices:
Copper IUD - The Secret Superstar
This little device is actually the MOST effective emergency contraception:
- Works up to 5 days after unprotected sex
- Over 99% effective at preventing pregnancy
- Bonus: Continues protecting you for 10-12 years
Downside? It requires a clinic visit and insertion can be uncomfortable. But if you're past the pill timeframe, it's your best bet.
The Big Plan B FAQ
Let's tackle those burning questions people type into Google at 2 AM:
| Question | Short Answer | Detailed Explanation |
|---|---|---|
| Can I take Plan B twice in one month? | Yes, but not ideal | It won't harm you, but frequent use makes it less effective and messes with your cycle. Use regular birth control instead. |
| Does alcohol affect Plan B? | No direct interaction | But alcohol might make you forget to take it or vomit it up. Not worth the risk in my opinion. |
| Can Plan B fail even if taken on time? | Yes, about 7-24% of the time | Factors like weight, ovulation timing, and medication interactions can reduce effectiveness |
| Will Plan B work if I'm already pregnant? | No | It doesn't terminate existing pregnancies. That's a whole different medication. |
| Do I need a prescription? | Not in the US | Available over-the-counter for all ages. Some stores keep it behind pharmacy counters though. |
Pro Tip: Many local health departments offer Plan B for free or low-cost. Planned Parenthood charges on a sliding scale (I've seen $0-$60). Call ahead if cost is an issue - no shame in asking!
Medications That Mess With Plan B
This really ticks me off - nobody warns you that common meds can make Plan B less effective:
- St. John's Wort (that "natural" mood booster)
- Seizure medications (Carbamazepine, Phenytoin)
- Tuberculosis drugs (Rifampin)
- Some HIV medications
- Certain antifungal treatments
If you take any regular medications, tell the pharmacist before buying Plan B. Better safe than sorry.
What Doctors Wish You Knew
I spoke with Dr. Allison Reyes, an OB-GYN with 15 years experience, who shared these insights:
- "The 'how long do you have to take plan b' question comes up daily. Many patients don't realize effectiveness plummets after day 1."
- "We see weight-related failures constantly. If you're over 165 lbs, Ella is worth the extra $10."
- "Emergency contraception doesn't protect against STDs. Get tested 2 weeks after unprotected sex."
- "Taking Plan B more than twice a year suggests you need better regular contraception."
The Morning After... Literally
Once you've navigated the "how long do you have to take a plan b" question and taken the pill, here's your roadmap:
- Day 1-3: Expect possible nausea, fatigue, dizziness
- Day 4-7: Watch for withdrawal bleeding (spotting) Week 2: Your period might arrive early or late - don't panic yet
- Week 3: Take a pregnancy test if no period
- Month Ahead: Consider long-term birth control options
Look, I've been through this emotional rollercoaster myself. That awful waiting period? It feels endless. But knowing exactly how long you have to take Plan B and what comes next takes some power back. You've got this.
When Plan B Isn't Enough
Sometimes despite doing everything right - taking it within the "how long do you have to take plan b" window, checking medication interactions - Plan B fails. It happened to my cousin. If you're facing an unplanned pregnancy, options include:
- Abortion pills (up to 10-12 weeks in most states)
- In-clinic abortion procedures
- Adoption planning
- Parenting resources
No judgment here. Just know your options and find a clinic you trust. Planned Parenthood or your local health department can discuss all paths confidentially.
The Bottom Line
So wrapping this up:
- The magic number for standard Plan B is 72 hours
- With Ella, you get 120 hours
- Earlier is always better - effectiveness drops hourly
- Weight and medications can sabotage effectiveness
- Copper IUD is your best late-stage option
- Test for pregnancy at 21 days
Knowing exactly how long you have to take Plan B removes one layer of panic from an already stressful situation. Print this guide or bookmark it - hopefully you won't need it, but if you do, you're prepared.