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Introduction

Pain affects women differently than men. Researchers are working to discover why this is. By understanding how and why women react differently, studies can be designed to come up with better, more effective treatments and pain management.

What we do know is many chronic illnesses, including fibromyalgia, irritable bowel syndrome (IBS), migraines, and multiple sclerosis, affect women more than men. Women also experience chronic pain associated with the illnesses more often and for longer periods than men.

Unfortunately women with disorders that cause chronic pain are also at a higher risk of developing other disorders with pain, sort of a domino effect. So, not only are women at higher risk of developing a painful condition, they are at a higher risk of having multiple painful conditions.

What is pain?

Pain is your body’s way of telling you that something is wrong. Scientifically speaking, the International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage." In other words, the nerves around the injured or hurt areas send a message to your brain to tell you that something is wrong. It’s a defense mechanism that sounds an alarm. Simply put, if you put your hand on a hot iron, the pain will make you pull it away to prevent any further damage.

A rare condition called congenital analgesia, or congenital insensitivity to pain, shuts down this alarm system. People with this disorder can’t feel pain so they don’t realize they’ve hurt themselves, sometimes severely. Although this condition isn’t common, it’s very serious. Our body needs the ability to feel pain to protect itself.

What causes pain?

Unfortunately, what causes your pain isn’t always obvious or treatable. The cause of pain can be one of many things, or even a combination. Some of the more common reasons for pain are:

• inflammation (swelling), such as swelling in the joints from rheumatoid arthritis
• tumors, either malignant (cancerous) or benign (not cancerous) pressing on an organ, bone, or a nerve. This pain can actually radiate or move to a different part of the body.
• blockage, like in the colon (bowels)
• infections
• tears or injuries to muscles, ligaments, or skin
• break in a bone
• stiffness in joints, muscles, etc.

Doctors usually refer to pain as acute or chronic. Acute is the term used to describe pain that is sudden and pain that usually has a definable cause, such as a broken toe, a toothache, or the pain from an incision if you just underwent surgery. On the other hand, chronic pain refers to pain that lasts longer than three to six months (some doctors disagree at what month pain should be considered chronic). The pain may be caused by something obvious, as with painful joints from arthritis, or it may not have a cause that can be pinpointed. This could be continuous back pain long after the original injury, for example. Chronic pain can be much more difficult to manage for this reason.

Possible reasons for gender differences in pain

Since the early days of medicine, women were often thought to be weaker or even emotionally unstable because they seemed to feel pain more often or more intensely than men. Today, we know differently. Research has shown that women aren’t weaker and there are actual biological differences between men and women and their interpretations of pain.

The female hormone, estrogen, may play a role in how women feel pain, but some study findings contradict each other. In some studies, researchers injected male animals with estrogen and the animals’ pain threshold dropped, making them more vulnerable to pain. When researchers injected testosterone, the male hormone, into female animals, they had higher pain thresholds.

Other studies showed different findings. When some researchers looked at how the brain released so-called natural pain relieving chemicals, called endorphins, the higher the estrogen level in the body, the better women were able to tolerate pain. The study compared men with women who had just had a menstrual period, when their estrogen levels were the lowest. The women were less able to tolerate pain than the men. Researchers repeated the study with women who wore an estrogen patch for a week before the trial. These women were much better able to tolerate pain than were the women in the previous trial and, in this trial, the women were sometimes better at tolerating the pain than the men.

Regardless of those study outcomes, migraines are a good case in point of a hormone connection with pain. As women go through life, their hormones change depending on their stage of life and their sexual maturation. Using migraines as example, not only do more women have migraines than men, when women go through puberty, have children, and later go through menopause, the frequency, intensity, and quality of their migraines can change considerably – either worsening or lessening. But with men, the quality and frequency of migraines don’t appear to change at all with sexual maturation.

Some painful disorders do affect more men

Although women do have more pain more often than men, they don’t have a monopoly on painful disorders. More men than women suffer from:

• gout (a build up of uric acid that can cause very painful joints)
• cluster headaches (short-length, piercing headaches that occur clusters over a few hours at a time)
• coronary heart disease
• ankylosing spondylitis (inflammation of the spinal joints)
• duodenal ulcers (a raw area in the lining of the upper intestine, just below the stomach)
• diseases of the pancreas (the organ that produces insulin)

And, of course, only men can have pain in their reproductive system:

• prostatitis
• prostate cancer
• penile cancer
• testicular pain
• testicular cancer

Differences seen in the brain

In 2003, researchers in California published a study showing that different parts of the brain became stimulated when reacting to pain, depending on the subject’s sex. The study compared men and women who had irritable bowel syndrome (IBS). They used a test called positron emission tomography (PET). PET allows doctors to see three-dimensional images of the brain.

When the researchers examined how the brains responded to pain, they found some of the areas in the brain overlapped. The same sections responded in both men and women, but there were also areas in the brain that reacted differently depending on the subject’s sex. In fact, the women tended to react in the emotional areas of the brain while the men reacted in the analytical centers of the brain.

In another study in 2006, researchers used magnetic resonance imaging (MRI), an advanced type of x-ray, to examine brain reactions to pain on healthy volunteers. As with the 2003 study, the researchers saw common responses between the men and women, but also that there were more areas in the male brain that were activated with pain than in the female brain.

Are the stereotypes true then?

Does this mean that the stereotypes about women and pain are true – that men act more rationally and analytically and women more emotionally? The studies suggest “yes and no.” The researchers compared their findings to the age-old flight or fight response to danger versus the nurturing responses that humans developed as they evolved. Men would have to react in one way because of their traditional role of providers (hunting and providing food) and protector of the family and homestead. Women would have to react differently in keeping with the role as family nurturer and caregiver. Neither response should be considered better than the other because the two responses could complement each other.

This way of thinking also brings up the more modern cultural influences of pain and pain reaction between the sexes. Boys were often taught to be strong and to not admit to pain or discomfort, while it was more acceptable for girls to do so. Boys were often told to “walk it off,” while girls might be cuddled and cared for.

Women-specific disorders

Many types of pain felt by women are caused by female-specific problems such as painful menstrual periods (dysmenorrhea). Other female-specific pain conditions include:

• back and pelvic pain during pregnancy
• labor pain
• chronic pelvic pain from disorders, such as endometriosis, tissue from the uterus migrates outside of the uterus
• pain in the vulva area, called vulvodynia, which has no known cause and no known cure

Many women are lucky in that they may not experience any of the women-specific disorders or, if they do they don’t feel them as intensely as others might, but research shows that many women do:

• between 40% and 90% of women experience painful periods
• 15% of women with painful periods describe them as excruciating
• 15% of women of reproductive age report chronic pelvic pain from any cause
• about 45% of pregnant women have lower back or pelvic pain
• 25% of pregnant women have lower back or pelvic pain severe enough to seek medical help
• over 95% of women who give birth experience labor pain
• it’s estimated that at least 18% of women experience vulvodynia, with burning, knife-like pain, pain on contact, or severe itching

Women-predominant disorders

Other illnesses and disorders, such as IBS, affect both men and women; but women are significantly over-represented in numbers. Statistics show that women with IBS outnumber men by two to one. Even illnesses such as arthritis are more common in women; according to the Arthritis Foundation, 24.3 million women are diagnosed with arthritis, compared with 17.1 million men.

We also can’t forget that women, on average, live longer than men. So when women get sick or have pain, they have the pain for longer periods, even if the women are diagnosed with fatal illnesses.

Why is it important to understand the gender differences in pain?

It’s one thing to acknowledge there’s a difference in pain between men and women, but what do we do with that information now that we have it? Why is it important to continue research?

Right now, more women are looking for help for their pain, using healthcare resources. Their pain is more severe and for longer periods, so society – as a whole – would benefit if these women could manage their pain more effectively. They would visit doctors less frequently, miss less work, and experience an overall better quality of life and be more productive in society.

As scientists continue to look for better, more effective analgesics (pain killers), they are learning they can’t depend on studies that have been done only on men or male animals; they have to test medications on women as often as they do on men. Even during the animal testing stages, more male animals are tested than females. In fact, a recent survey of studies showed that the majority of studies, 79%, used only male animals.

Using more female subjects in medication studies could make a big difference in the understanding of how medications work and what doses may be better for girls and women. For example, there’s a debate in the scientific community whether opioids (government-controlled analgesics because of their addictive quality) work better in males than females. But, research is also showing that perhaps different types of opioids work better on women than men.

Many women take anti-inflammatory drugs for chronic pain. These medications are often given for arthritis, fibromyalgia, and many of the disorders that are more common in women. However, some research shows that anti-inflammatories aren’t as effective in women as in men – although this isn’t definite and other researchers have found no difference between men and women. But the fact that there’s a even a question about the effectiveness means that this needs to be examined more closely.

Another issue that researchers need to investigate goes back to the female hormones. We know that estrogen plays some role in pain thresholds, but what role does it play on medications and their effectiveness? Could it be that certain types of medications would be most effective at certain times, depending on a woman’s estrogen level? These are questions that need to be answered.

Alternative medicine

Complementary and alternative medicine is becoming more popular in North America. Women seem to be more open to trying alternative approaches to help relieve their pain. Interestingly, the widest gap between men and women is with the use of prayer; more women use prayer (mind-body therapy) than men.
In the United States, the 10 most commonly used complementary therapies are:

1. prayer for one’s own health
2. prayer by others
3. use of natural products
4. deep breathing exercises
5. participation in prayer group
6. meditation
7. chiropractics
8. yoga
9. massage
10. diet

Most commonly, these therapies are used for:

• back pain/problems
• neck pain/problems
• joint stiffness
• joint pain
• anxiety
• depression

More to understand

There are so many aspects to how someone feels pain and copes with it that researchers need to find a way encompass the many issues. Aside from the medications, treatments, and alternative therapies discussed above, other issues that have an impact on pain range from anticipating pain, catastrophizing (imagining the worst), emotional reactions, and expectations of how treatments will work. In one study of men and women who had osteoarthritis of the knee, researchers found that women used more problem solving to cope with the pain, but had more pain later in the day then the men. On the other hand, men were able to cope with the pain more as the day went on.

In another study of men and women who had osteoarthritis or rheumatoid arthritis, researchers kept track of the subjects’ ability to cope with pain through self-diaries. Regardless of the type of arthritis they had, women reported more daily pain but also used more emotion-focused strategies than men to manage the pain. In both studies, men were more likely to be in a negative mood the day after a painful evening than were women.

With the knowledge that there are real, identifiable differences between men and women, we can hope that it won’t be long before treatments are individualized for each.