AUSTIN (KXAN) — The Supreme Court of the United States overturned the nearly 50-year-old Roe v. Wade precedent Friday, which granted federal protection and access for abortion. Here in Texas, state leaders had previously instituted a 30-day “trigger law,” should Roe be overturned.

While emergency contraceptives are still legal federally, Supreme Court Justice Clarence Thomas issued a concurring opinion Friday that invited the court to revisit precedent cases that authorized contraception access. That ruling, 1965’s Griswold v. Connecticut, prohibits states from making the use of contraception by couples illegal; a 1972 ruling extended that right to unmarried people.

Here’s a breakdown of what emergency contraceptives are, how they differ from contraceptives and abortion pills and how they are used.

What are emergency contraceptives?

Emergency contraceptives, also referred to as “morning-after” pills, are medications used following unprotected sex to help prevent pregnancy. There’s a variety of brands on the market, including Plan B One Stop, My Way, Preventeza, AfterPill and My Choice.

Most morning-after pills can be taken three-to-five days after unprotected sex. However, medical officials say the medications are most effective when taken three days after unprotected sex.

However, there are discrepancies in their effectiveness, based on a person’s weight and body mass index. The efficacy of many over-the-counter brands wane for people who weigh more than 165 pounds, as well as a BMI of 26 or greater, per the Austin Women’s Health Center.

Ella, a prescription-issued emergency contraceptive, is marketed as 85% at prevented unplanned pregnancies and is effective for people weighing more than 165 pounds. The drug maintains its efficacy when taken within five days of unprotected sex.

What are the side effects of emergency contraceptives?

Morning-after pills have been linked to mild side effects that could include the following:

  • Nausea and vomiting
  • Dizziness
  • Fatigue
  • Headache
  • Breast tenderness
  • Bleeding between periods, heavier menstrual bleeding
  • Cramps or lower abdominal pain

Following emergency contraceptive use, some people’s next menstrual cycles can be delayed up to one week, according to the Mayo Clinic. Users are recommended to take a pregnancy test if they don’t get their period three-to-four weeks after taking an emergency contraceptive.

How are emergency contraceptives different from oral contraceptives or abortion pills?

Oral contraceptives, or birth control pills, are medications used to prevent pregnancy. Emergency contraceptives are used as a backup form of contraception if birth control pills, or other contraceptives like condoms, fail.

Prescriptions are needed for birth control pills, while many emergency contraceptives — excluding prescription-only ella — are available for over-the-counter purchases.

Abortion pills are used to terminate an already-existing pregnancy, as opposed to preventing pregnancy. The most common medical abortions are done by taking the pills Mifeprex and Cytotec within seven weeks of the first day of a person’s last period, per Mayo Clinic.

Medical abortions aren’t used for people who have been pregnant for more than nine weeks, have an intrauterine device, have a suspected ectopic pregnancy, take a blood thinner or have certain bleeding disorders. For people who can’t have a medically-induced abortion, a dilation and curettage (D&C) procedure is an option.

What happens if someone uses emergency contraceptives multiple times?

No specific research has linked repeated emergency contraceptive use to longer-term fertility or health complications, according to a study conducted by the American College of Obstetricians and Gynecologists. However, ACOG does not recommend emergency contraceptives as an alternative to birth control due to menstrual irregularities linked to the emergency contraception.

Do emergency contraceptives have an expiration date?

Emergency contraceptives, like Plan B, have a shelf life of four years while ella expires after three years, per Verywell Health. Expiration information is printed on the side of the product box.

Emergency contraceptives are best kept in a dry, dark place and stored at room temperature, between 68 and 77 degrees.