What’s the difference between a copper IUD and a hormonal IUD?

Hormonal and copper IUDs

An intrauterine device (IUD) is a small T-shaped object that is inserted into (and eventually removed from) the uterus by a health care professional and provides long-term, reversible birth control. While the IUD is one of the most reliable contraceptives (more than 99 percent effective), it doesn’t protect against sexually transmitted diseases (STDs), so a condom is still needed for safer sex. There are currently five IUDs on the market: four hormonal (Mirena, Kyleena, Liletta and Skyla) and one copper (Paragard). They differ in a few ways.

Copper, which is toxic to sperm, causes the movement of sperm to change in ways that prevent the sperm from fertilizing an egg. The copper IUD can also be used as emergency contraception; it’s around 99.9 percent effective when inserted within five days after unprotected sex (with the added bonus that you’ll then have long-term birth control if you leave it in place). The copper IUD is a great choice for someone who prefers a non-hormonal birth control option.

Hormonal IUDs, on the other hand, release a synthetic hormone called progestin that causes cervical mucus to thicken so sperm cannot reach the egg. The hormone can also often stop ovulation, which means that there would be no egg present for the sperm to fertilize. A hormonal IUD may cause a lighter period or none at all and sometimes reduces menstrual cramping. However, a hormonal IUD cannot be used as emergency contraception. Hormonal IUDs, which last from three to seven years, don’t last as long as copper ones, which can work for up to 12 years.