The morning-after pill following unprotected sex

Emergency contraception pills are available in three forms, each with specific requirements and factors to consider.

Levonorgestrel (Plan B One-Step®, Next Choice®, Take Action™)

• What it is: A progestin-only pill that delays or prevents ovulation.
• Where to get it: Available over the counter. Ask the pharmacist; no prescription is needed if you are 17 or older.
• When to take it: Most effective within 24 hours (about 94%). Effectiveness drops after 72 hours (to about 58%). Take it as soon as possible, within five days.
• What to know: Less effective for people who weigh more than 165 pounds.

Ulipristal acetate (Ella®)

• What it is: An antiprogestin pill that blocks progesterone receptors to delay ovulation.
• Where to get it: Requires a prescription from a health care provider.
• When to take it: About 98% effective if taken within 72 hours and remains effective for up to five days. Taken as a single 30 mg tablet.
• What to know: Do not start hormonal birth control for five days after taking this pill. More effective for people with higher body weight.

Combined birth control pills

• What it is: Pills containing both estrogen and progestin.
• Where to get it: Contact your health care provider or clinic for the correct dosing.
• When to take it: Two to four pills right away, then two to four more 12 hours later. Must be taken within five days.
• What to know: Less effective than other methods and more likely to cause side effects.

• Levonorgestrel or combined birth control pills: Restart your birth control pill, patch, or ring the next day. Use condoms or abstain for seven days until your birth control is effective.
• Ulipristal acetate: Wait five days before starting hormonal birth control. Use condoms or abstain for seven days after restarting.
• Check for pregnancy: If you don’t get your period within three weeks or have irregular bleeding, take a pregnancy test.