Fibromyalgia is an often-misunderstood form of rheumatoid disease.

It’s usually classified alongside other forms of rheumatic disorders, such as arthritis and lupus. However, the exact cause of fibromyalgia remains unknown.

To add to the confusion, fibromyalgia predominantly affects women. According to the Centers for Disease Control and Prevention (CDC), it’s twice as common in women as it is in men.

While anyone can get fibromyalgia, hormones are thought to be a possible explanation for this gender bias. Learn more about how this painful syndrome affects women, and what can be done about it.

The CDC estimates that about 4 million adults in the United States have fibromyalgia. It can technically develop in anyone at any age, but fibromyalgia typically develops in middle-aged adults.

Since the disorder primarily occurs in women, being female is a risk factor.

Other risk factors that increase your chances of developing fibromyalgia include:

Having a history of any of the above factors doesn’t necessarily mean you’ll develop fibromyalgia. You should still be aware of these risks and discuss them with your doctor if you’re concerned. Find out more about fibromyalgia causes and risk factors.

The most common symptoms of fibromyalgia tend to affect both men and women equally. But not all people with the disorder experience pain in the same spots. These points of pressure can even change day to day.

Fibromyalgia often feels like extreme muscle pain, usually accompanied by fatigue. Some of the most common symptoms include:

There’s no conclusive link between specific hormones and fibromyalgia, but researchers have noted some possible strong connections.

A 2015 study found that women with fibromyalgia are also more likely to have frequent symptoms of premenstrual syndrome (PMS) and primary dysmenorrhea, or painful menstrual periods. Women in the study group were found to experience extreme lower abdominal and lower back pain for two days before menstruation.

Other researchers point to another explanation for the prevalence of fibromyalgia in women.

A 2010 Danish study suggested that men might be underdiagnosed with fibromyalgia because of a lack of noticeable “tender points.” So while men might not have PMS symptoms, for example, they might have other forms of mild pressure points that are often ignored. Learn more about fibromyalgia tender points.

Fibromyalgia can be difficult to diagnose because the signs aren’t visible on an X-ray, blood test, or other exam. Women who experience painful menstrual cycles might also pass it off as a normal hormonal issue.

According to the Mayo Clinic, most people experience widespread pain for three months or longer before being diagnosed with fibromyalgia. A rheumatologist will also rule out any other possible causes of pain before diagnosing you.

If you’re diagnosed with fibromyalgia, your treatment options may include:

It’s important to note that there’s no cure for fibromyalgia. The goal of treatment is to alleviate pain and improve your quality of life. Discover seven natural remedies that may also help with fibromyalgia pain.

Fibromyalgia is considered a chronic condition that can last a lifetime. This is true in both men and women.

The good news is that it isn’t considered a progressive disease — it doesn’t cause any direct damage to the body. This is different from rheumatoid arthritis (RA), which can damage joints. Also, fibromyalgia isn’t fatal.

However, this doesn’t necessarily ease the pain that millions of women with fibromyalgia experience. The key is to keep up with your treatment plan, and to see your rheumatologist if it’s not working.

The more researchers learn about the disorder and its effects on adults with the condition, the more hope there is for preventive treatments in the future.