Asthma Is Worse for Women. Doctors Are Finally Starting to Figure Out Why.

Before puberty, boys are more likely than girls to have asthma, and are also more likely to have severe symptoms than their female peers. But something happens during that transitional time of life so that afterwards, the situation flips.

Exactly what happens, experts aren’t yet sure. But about one in 10 adult women, almost twice as many compared to men, in the United States have asthma, and they’re more likely than men to have asthmatic attacks that bring them to the emergency room or keep them hospitalized. What’s more, certain types of asthma that are more common in women don’t respond to the typical treatment, says Patricia Silveyra, professor at Indiana University School of Public Health-Bloomington.

The plot thickens as women age. Symptoms sometimes improve—or grow worse—during certain phases of the menstrual cycle, pregnancy, and menopause, says Dawn DeMeo, a pulmonary and critical care physician at Mass General Brigham.

While sex differences in asthma have been recorded for decades, the field is only more recently beginning to understand the mechanisms behind them, Silveyra says. “This is not unique to asthma, but rather reflects a broader history in biomedical research where women have been underrepresented or not analyzed separately,” she says.

For instance, for decades, many trials for asthma treatments in the U.S. primarily tested drugs in men, says Ayobami T. Akenroye, assistant professor of allergy and immunology at Harvard Medical School. A major turning point was when NIH implemented the Sex as a Biological Variable (SABV) policy, which took effect in 2016. “That policy helped formalize the expectation that sex should be considered in the design, analysis, and reporting of studies, and since then, there has been much greater attention to sex differences in asthma," says Silveyra.

The good news is that progress is being made when it comes to treating asthma for both sexes, including the advent of new biologics as well as research on whether GLP-1s could one day be a part of treatment plans.

What Impacts Sex Differences in Asthma

Asthma isn’t one disease. It’s a broad term for multiple types of chronic lung disease that leads to narrowing airways, and researchers have found a few ways sex differences influence symptoms. Genetics, differences in lifestyle and environmental exposures, and sex hormones like estrogen and androgens, all play distinct roles.

When it comes to genetics, there are sex-specific genes, gene variants, and mircoRNAs (i.e. small nucleic acids that are structurally similar to DNA) that are directly linked to lung function, lung inflammation, and asthma in general, per a study co-authored by Silveyra. “Sex specific genetics does not mean women have entirely different asthma genes,” Silveyra explains. “It means the same gene or variant can behave differently in male and female bodies.”

But genetics don’t paint the full picture. There also may be differences in how the lungs develop in boys and girls.  Girls have a smaller ratio of the opening of their airway (i.e. larynx) to the total volume of their lungs compared to boys. As boys get older, the lungs get bigger which can alleviate childhood asthma, says Akenroye. But women’s lungs remain relatively smaller.

Environmental factors also contribute. Women are perhaps more likely to be exposed to certain irritants, such as cooking fumes and cleaning products, Akenroye says. Women who cleaned for work reported 13.7 percent doctor-diagnosed asthma compared to 12.3 percent of women who cleaned at home and 9.6 percent of women who did not clean, according to a large cohort study.

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Then there are the sex hormones. Female hormones like estradiol tend to be more pro-inflammatory while androgens, “male” hormones, tend to be more anti-inflammatory, says Silveyra. Estradiol and progesterone increase TH17 immune cells production of an inflammatory molecule (called IL-17A) that is associated with severe asthma, reports a study in The Journal of Allergy and Clinical Immunology. “Changes in estrogen and androgen levels that happen starting at puberty—but can also fluctuate for women during pregnancy or at menopause—are important in regulating airway inflammation that can drive asthma,” says Dawn Newcomb, associate professor of Medicine at Vanderbilt University, who led the study.

Sex hormones can also play a role in amping up another asthma risk factor: obesity. “Obesity is a big modifier of asthma, especially in women,” says Silveyra, in part because adipose tissue (i.e. fat) can impact estrogen signaling. Obesity increases the risk of asthma developing and “complicates its clinical course” by altering respiratory mechanics, immune responses, and treatment responsiveness, according to a 2025 narrative review in The Journal of International Medical Research.

How Hormonal Changes Affect Asthma Symptoms

Complicating matters, asthma symptoms in women can fluctuate over time, corresponding with changes in a woman’s menstrual cycle, pregnancy, and menopause.

Up to 40 percent of women with asthma say their menstrual cycle impacts their symptoms, per a review in the Journal of Allergy and Clinical Immunology. (Silveyra says that while this number is largely cited, it’s likely that it’s even higher.) In general, women tend to report that their asthma gets worse a few days before their period (called the luteal phase), or at the very beginning of their period, says Silveyra. This could be due estrogen and progesterone levels rising after ovulation before falling again just before menstruation. These hormonal fluctuations “may impact airway inflammation, bronchial hyperresponsiveness, or twitchiness in the airways,” says DeMeo.

Some experts hypothesize that hormonal fluctuations are also responsible for the roughly 40 percent of women who experience worsening asthma symptoms during pregnancy. “It's the second and the third trimester where most of the exacerbations in asthma occur,” says Silveyra, “and that correlates with higher hormone levels, higher cortisol levels, bigger belly, more weight.” But other factors could contribute: A 2025 study in the European Respiratory Journal explains some women stop asthma treatment when they become pregnant; so the worsening of some symptoms could be caused by this behavior change. Other factors linked with pregnancy could exacerbate asthma, DeMeo says, including immune system changes, gastroesophageal reflux, and even nasal congestion.

Still, 30 percent of women with asthma who become pregnant will not experience any changes and 30 percent will see an improvement, says Silveyra. (Doctors call this the "30 percent rule.") In general, those who have worse symptoms to begin with are more likely to get worse during pregnancy, but it’s still not entirely clear exactly why this happens.

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As women age into menopause and hormones continue to fluctuate, researchers generally note a decline in asthma. But factoring in obesity, which tends to increase during menopause, or hormone therapy use muddies the picture. Hormone therapy in particular is a “triple-edged sword,” says DeMeo, as some studies suggest these estrogen-containing therapies may increase asthma risk or exacerbate symptoms.

A 2025 Mayo Clinic study suggested there is no link at all between menopause and asthma, and that the previously reported links are confounded by age, obesity, and hormone therapy. "The literature is really confusing even to us as researchers and clinicians,” DeMeo says. Certainly, “there are some women who never had asthma and start having asthma later in life, and there are women that have asthma and then when they reach menopause, asthma goes away,” Silveyra says.

Why Women Don’t Respond to Treatments

Because women are more likely to have more severe asthma, they require more treatments compared to men, Newcomb adds. But that’s where a problem arises. “We know women may not respond as well to inhaled steroids,” DeMeo says. Steroid inhalers are a cornerstone of asthma treatment, used to reduce inflammation at the cellular level. Estrogen may worsen airway inflammation and alter how cells react to them.

As an alternative to steroids, there are currently seven biologics on the market. These disrupt inflammation-causing cells or molecules, but they target a type of asthma that is not more prevalent in women. “I'm excited about other biologics that are in the [research] pipeline now that are targeting the patients who might not respond well to the ones on the market,” Akenroye says. 

Unfortunately, to date the studies of biologics have not been designed to evaluate sex differences in efficacy. Still, scientists are hopeful about progress: "The awareness about sex-specific presentations has grown, and so maybe we're not too far away where trials will be powered to detect sex differences,” DeMeo says.

Another class of medications that is emerging as a possible treatment are GLP-1s, which are commonly used to treat diabetes and obesity. “If we have an opportunity to also treat obesity, which is a very common comorbidity in our asthma population, hopefully that could also benefit women,” says Akenroye. While GLP-1s aren’t FDA-approved for asthma therapy yet, DeMeo says doctors and researchers are paying close attention to new data.

For women without diagnosed asthma, experts say to take any respiratory symptoms seriously. Don’t write off any shortness of breath during menopause as anxiety, DeMeo says, but instead see a doctor. In terms of prevention, the experts say avoiding smoking and vaping as well as occupational exposures (like dust and fumes), and managing obesity are essential. Akenroye adds that mental health is also important because psychosocial stress can be an asthma trigger.

Experts also agree that symptom tracking can be a great way to help you—and your doctor—keep tabs on your own individual biology and how that may impact your personalized treatment plan, such as using an inhaler more often or being extra vigilant of certain triggers during the luteal phase of your cycle, or via oral contraceptives or hormone stabilizers.

Now that sex-specific research is happening in earnest, the experts hope that someday soon we’ll have more answers than questions when it comes to why women are more likely to have asthma—and how we can best treat them.