The vaginal ring is a small, flexible ring that releases hormones over time and which a woman inserts into her vagina once a month to prevent pregnancy. It is left in place for three weeks and taken out for the remaining week each month.

The vaginal ring is commonly called NuvaRing, its brand name.

Like other methods of birth control, NuvaRing releases hormones, the same hormones as in the birth control pill — estrogen and progestin. The hormones work by keeping a woman’s ovaries from releasing eggs — ovulation, and also by thickening a woman’s cervical mucus, and by thinning the lining of the uterus.

Less than 1 out of 100 women will get pregnant each year if they always use NuvaRing as directed.

Certain medicines and supplements may make NuvaRing less effective. These include:

  • the antibiotic rifampin — other antibiotics do not make the ring less effective
  • certain medicines that are taken by mouth for yeast infections
  • certain HIV medicines
  • certain anti-seizure medicines
  • St. John's wort

Most women can use NuvaRing safely, but certain conditions increase the risk of serious side effects.

Many women who use the vaginal ring have more regular, lighter, and shorter periods. And a woman’s ability to become pregnant returns quickly when use of the ring is stopped.

Because the ring works like the pill, it probably offers the same benefits. These health benefits may include some protection against

  • acne
  • bad menstrual cramps
  • breast growths that are not cancer
  • ectopic pregnancy
  • endometrial and ovarian cancers — protection increases with each year of use
  • iron deficiency anemia
  • ovarian cysts
  • pelvic inflammatory disease, which often leads to infertility when left untreated
  • premenstrual symptoms, including headaches and depression

Because NuvaRing works like the pill, it probably carries the same possible disadvantages.

Some of the most common side effects usually clear up after two or three months. They include

  • bleeding between periods
  • breast tenderness
  • nausea and vomiting
  • increased vaginal discharge
  • vaginal irritation
  • infection
  • change in a woman’s sexual desire.

Women who use birth control with estrogen — like NuvaRing —have a slightly greater chance of certain serious problems than nonusers. The most serious — in very rare cases — may be fatal. These include heart attack, stroke, or having a blood clot in the legs, lungs, heart, or brain, developing high blood pressure, liver tumors, gallstones, or yellowing of the skin or eyes (jaundice). The risk for these problems increases if you

  • are age 35 or older
  • are very overweight
  • have certain inherited blood-clotting disorders
  • have diabetes
  • have high blood pressure
  • have high cholesterol
  • need prolonged bed rest
  • smoke

Serious problems usually have warning signs. Report any of these signs to your health care provider as soon as possible:

  • a new lump in your breast
  • a sudden very bad headache
  • achy soreness in the leg
  • aura — seeing bright, flashing zigzag lines, usually before a very bad headache
  • bad pain in your abdomen or chest
  • headaches that are different, worse, or happen more often than usual
  • no period after having a period every month
  • trouble breathing
  • yellowing of the skin or eyes