Olivia Munn is going through medically induced menopause after breast cancer treatment. Here's what that means.

Olivia Munn is in medically induced menopause as a result of treatment to keep her breast cancer from recurring, the actress told People in an exclusive new interview. Munn, who last month revealed she’d undergone a double mastectomy after being diagnosed with luminal B, told the magazine that treatment for the aggressive form of breast cancer included four surgeries in the span of just 10 months and, now, hormone-suppressing treatment that has triggered menopausal symptoms. “I’m constantly thinking it’s hot, my hair is thinning and I’m tired a lot,” she told People. So what does it mean to be in medically induced menopause? Here’s what to know.

What is medically induced menopause and what treatments cause it?

Menopause occurs when the ovaries’ production of two sex hormones — estrogen and progesterone — slows and eventually stops as a result of the normal aging process, typically beginning between ages 45 and 55, according to the National Institute on Aging. As these hormones decline, periods become irregular and eventually stop altogether, and a number of other physiological changes are prompted.

Some medical treatments can send people into menopause early. Medically induced menopause can be triggered by several different types of treatments for breast, ovarian or uterine cancer or, less commonly, for endometriosis. According to BreastCancer.org, these include:

• Surgical removal of the ovaries, uterus or both to treat or prevent cancer and, in some cases, endometriosis

• Radiation to treat cancer (including ovarian, uterine or colorectal cancer)

• Chemotherapy to treat cancer

• Hormone suppression therapy to treat or prevent recurrences of hormone-positive breast, ovarian or uterine cancer

In Munn’s case, hormone suppression treatment is being used to stop her ovaries from producing estrogen to help prevent her breast cancer from returning after she had surgery to remove the cancer and both breasts, she told People. According to Munn, whose type of cancer is fueled by hormones, she hasn’t needed chemotherapy or radiation, but hormone suppressing treatment to cut off this fuel source should reduce the chances that tumors can form again. “If somebody has an estrogen-sensitive tumor, doctors try to block their estrogen production, so they use these drugs that basically shut the ovaries down,” Dr. Mary Jane Minkin, co-director of the sexuality, intimacy and menopause for cancer survivors program at Yale University’s Smilow Cancer Center, tells Yahoo Life.

What are the symptoms of medically induced menopause?

Menopause, whether induced by age or medication, is the same, so the symptoms are identical. Common symptoms, according to the Mayo Clinic include:

• Irregular periods

• Vaginal dryness

• Hot flashes

• Chills

• Night sweats

• Sleep problems

• Mood changes

• Weight gain and slowed metabolism

• Thinning hair and dry skin

• Loss of breast fullness

For people going through medically induced menopause, the difference is that these changes are happening more suddenly. “It’ll act really quickly,” Minkin says. She notes that about 20% of women don’t get hot flashes when they go through menopause but, for people like Munn going through medically induced menopause, hot flashes are probably more common. “These people are going from a young person’s level of estrogen to menopause, so we do tell people that it can be sudden.”

While people on hormone suppressing therapies for breast cancer can’t take hormone replacement therapy, there are prescriptions and herbal treatments that can help ease symptoms, says Minkin, who discusses some of these options on her website, MadameOvary.com.

How long does medically induced menopause last?

That depends on what treatment has triggered menopause. For those who have surgery to remove the ovaries, uterus or both, menopause will be permanent and, if the ovaries were removed, it begins immediately. After chemotherapy, sometimes the ovaries begin producing estrogen and menopause ends. But sometimes they don’t, Minkin says.

For those taking hormone-suppressing medications, such as Munn, menopause will last as long as the course of treatment does. According to a National Institutes of Health study, breast cancer survivors are on these medications for an average of 4.04 years. Minkin says that anywhere from five to 10 years of treatment is common, depending on the type and stage of breast cancer someone was diagnosed with.

Once someone who was otherwise premenopausal stops taking these types of medications, the ovaries should resume producing estrogen and progesterone again and menstrual cycles will resume. One study published in the journal Fertility and Sterility in 2016 found that periods resumed within two years of treatment for 90% of women, meaning they were no longer in menopause.

Can a woman have children after going through medically induced menopause?

Yes — at least in theory. “If the woman is fairly young, she does the medication for five years and then stops it and her ovaries do come back” — meaning her body is actively producing estrogen and progesterone to release eggs — “then that’s OK as far as childbearing, and she may well be able to get pregnant,” Minkin says. BreastCancer.org also suggests that a woman’s fertility will return after treatment has ended.

It’s not guaranteed, however. Minkin says that if a woman has viable eggs, then she may still be able to conceive with IVF. But “if a woman stops therapies and the ovaries don’t wake up, then she’s gone through menopause.”