By Maggie Fox

Researchers have now found that the hot flashes which make menopause so miserable, can last an average of seven years, and persist for an average of 10 years among African-American women.

The study is one of only a very few to look at how the symptoms of menopause affect women in real life, and what it reveals is not promising.

"This study suggests that very short-term treatment may not control women's hot flashes and night sweats for their total duration," said Dr. JoAnn Manson of Brigham and Women's Hospital in Boston.

The study of more than 1,400 women found that hot flashes and night sweats last on average nearly seven and a half years. But some women suffer hot flashes and night sweats for 14 years.

And women who start having these symptoms earlier usually suffer them for longer than the average, Nancy Avis of Wake Forest University's school of medicine and colleagues found.

They looked at a detailed study of women from various U.S. ethnic groups who were interviewed between 1996 and 2013. They focused on 1,449 of them who had frequent vasomotor symptoms, better known as hot flashes.

According to the study, these women suffered their symptoms on at least six days over the previous two weeks.

The women who were still having their periods when the hot flashes started, ended up having symptoms for the longest time— nearly 12 years on average. Women who didn't have the symptoms until after their final menstrual period only had to tough it out for a little over three years.

"Compared with women of other racial/ethnic groups, African American women reported the longest total vasomotor symptom duration," the researchers wrote.

Women of Japanese and Chinese descent reported symptoms lasting five years. Hispanic women reported nearly nine years of the misery.

"These findings can help health care professionals counsel patients about expectations regarding vasomotor symptoms and assist women in making treatment decisions based on the probability of their (symptoms) persisting," the researchers wrote.

Manson said this doesn't necessarily mean that women should consider taking hormone replacement therapy for 14 years. Manson is a former president of the North American Menopause Society who also led the Women's Health Initiative study that examined the safety of hormone therapy.

The usual advice for hormone therapy is for a woman to take the lowest possible dose for the shortest possible period of time, because hormone therapy can raise the risk of heart disease and certain cancers, such as breast and ovarian cancers.

However these findings demonstrate that women may need multiple treatments to control their symptoms.

That could include a short course of HRT, which is safer for younger women first entering menopause who don't have a high risk of heart disease. Then, women might consider non-hormone treatments, which can include paroxetine and other antidepressants.

"We recommend starting with lifestyle," Manson said. That includes identifying the triggers for hot flashes, which can include hot drinks or spicy foods for some women, alcohol and smoking for others. "There are many triggers that women have to personalize," she said.

"Women really need to think about all the pros and cons of hormone therapy and decide where their own thoughts and feelings lie," said Dr. Margery Gass, executive director for The North American Menopause Society.

Manson and Gass said women should feel free to describe their symptoms to their physicians and need to know now that menopause might not be something that will only last a few months or years.

"If you feel that your symptoms are being dismissed and you are not being given an opportunity to discuss symptoms and treatments options available to you, then you really need to seek another health care provider," Manson said.

Gass also points out that the study is far from being the last word on menopause. For one thing, it excluded women who had turned to hormone therapies. Those may be the women who are bothered most by their symptoms, she said.