What is Emergency Contraception?

Medically reviewed by Carmen Pope, BPharm. Last updated on Feb 27, 2025.

What is Emergency Contraception?

Emergency contraception helps prevent pregnancy after unprotected sex. It is useful in cases of:

• Missed or failed birth control (also called contraceptives), such as a forgotten pill or no condom
• Unprotected intercourse
• Sexual assault.

There are 3 main types of emergency contraception in the United States:

• Levonorgestrel-based pills (Plan B, generics), also referred to as Morning After Pills.
• Ulipristal-containing pills (ella, generic)
• Copper IUDs (ParaGard). 

1. Levonorgestrel-based pills (Plan B, generics)

Also referred to as the Morning After Pill.

Availability: Over-the-counter (OTC) without prescription, ID, or age restrictions

Cost: $35-$50 (generics are typically less expensive than brand names and may sell for as little as $8 from some retailers)

Effectiveness: Most reliable within 72 hours (3 days) of unprotected sex. See What are the signs that Plan B didn't work? for more information.

How it works: Stops or delays ovulation

Available brands and generics

All contain levonorgestrel 1.5 mg.

• Plan B One-Step
• Aftera
• AfterPill
• AfterPlan
• Athentia Next
• BionaFem
• EContra EZ
• EContra One-Step
• Fallback Solo
• Morning After
• My Choice
• My Way
• New Day
• Next Choice One Dose
• Opcicon One-Step
• Option 2
• PostDay One-Step
• Preventeza
• React
• Take Action

2. Ulipristal-containing pills (ella)

Availability: Prescription only (available through online prescription services)

Cost: Approximately $67

Effectiveness: Should be taken within 5 days of unprotected sex

How it works: Blocks progesterone receptor, inhibits or delays ovulation

Available brands and generics

All contain ulipristal 30 mg.

• ella
• Logilia.

3. Copper IUD (Paragard)

Availability: Must be inserted by a healthcare professional

Effectiveness: Up to 99% effective if inserted within 5 days of unprotected sex

Duration: Can be left in place for up to 10 years

How it works: Produces an inflammatory reaction that interferes with sperm motility, egg fertilization, and possibly implantation.

See How does the Paragard IUD work? for more information.

Available brands and generics

Consists of a strand of copper wound around a small T-shaped device.

• ParaGard T 380A

Important facts about Emergency Contraception.

Timing

• Take emergency contraception as soon as possible after unprotected sex
• Levonorgestrel-ECPs: Most effective within 72 hours (3 days); moderate effectiveness within 5 days
• Ulipristal ECPs: Most effective within 5 days
• Copper IUDs: Most effective within 5 days.

Usage Guidelines

• Don't take more than one type of ECP at the same time (don't combine Progestin-ECPs with Ulipristal ECPs)
• Don't take more pills than recommended
• If you vomit within three hours of taking an oral ECP, take another dose
• Your next period should start when expected (it may be a few days early or late)
• Consider regular birth control if you're having frequent sex.

Key Differences Between Options

Levonorgestrel ECPs

• Take within 72 hours (3 days), although these may have moderate effectiveness up to 5 days
• Works by stopping/delaying ovulation
• May be less effective for women who weigh more than 165 lbs (75 kg) or have BMI >25
• Available OTC without prescription, ID, or age restrictions
• Will not affect existing pregnancy (not an abortifacient).

Ulipristal ECPs

• Effective within 120 hours (5 days)
• Blocks progesterone hormone receptor
• Wait 5 days before starting other hormonal birth control after taking
• Should not be used if pregnant or by girls who haven't started periods
• Should not be used twice in same menstrual cycle
• Requires prescription (except in select states where pharmacists can prescribe).

Copper IUDs

• 99% effective for emergency contraception
• Provides continued protection for up to 10 years
• No hormones; suitable during breastfeeding
• May cause heavier, more painful periods.

Where to buy Emergency Contraception

The morning-after pill containing levonorgestrel is available to buy from most major retail stores and is usually located near the condoms or other items for sexual health. It can also be purchased online for same day delivery or curbside pickup through CVS, Target, or Walgreens.

• There are no minimum age or ID requirements for purchase in all 50 U.S. states.

The sooner you take it, the better it works, but you must take it within 72 hours of sex.

Safety Information

Emergency contraception is generally safe, especially when used as directed.

When to See a Doctor

Seek medical attention if you develop:

• Severe abdominal, calf, or leg pain
• Chest pain, cough, or shortness of breath
• Severe headache, dizziness, or numbness
• Blurred vision or trouble speaking
• Yellowish tint to skin or eyes (jaundice)
• Period delayed by more than one week after taking ECP.

Side Effects

Oral ECPs (usually mild and short-term)

• Nausea or vomiting
• Irregular bleeding, spotting, menstrual changes
• Headache or dizziness
• Breast tenderness
• Fatigue
• Stomach pain or cramps.

See Can Plan B make your period late or cause bleeding?

Copper IUDs

• Pain during insertion
• Cramping or backaches for a few days after
• Heavier/more painful periods, spotting
• Rare complications: dislodgement (uncommon), perforation (1 in 1000).

See also

• Birth Control Pills (Oral Contraceptives)
• Birth Control Pills and Your Period
• Birth Control Pills: Benefits, Risks & Side Effects
• Birth Control Pills: Why do I get breakthrough bleeding?
• Emergency Contraception: What You Need to Know
• Grapefruit and Birth Control Pills: Your Questions Answered
• Missed your birth control pill? Here's what to do
• Non-hormonal Methods of Birth Control
• What are the options for permanent birth control?

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer