Allergies are common in the United States, where nearly one-third of adults have a seasonal allergy,
eczema, or a
food allergy.
And about 8 percent of adults have
asthma, which can be an allergic condition.
Take a closer look at those numbers, however, and one thing becomes clear: Allergies affect men and women differently.
"When children are young, boys get allergic conditions like asthma and hay fever more often than girls," says
Bradley Locke, DO, a board-certified allergist-immunologist with Prevea Allouez Allergy in Green Bay, Wisconsin, and a spokesperson for the American College of Allergy, Asthma, and Immunology. "After puberty, this changes. Adult women tend to have allergies more often and more severely than men."
Here’s what we know about why this happens.
There are marked differences in allergy rates among the sexes before and after the teenage years.
"Generally, men have fewer allergies than women, including less allergic rhinitis, asthma, and contact allergies after puberty," says
Corinna Bowser, MD, who is board-certified in allergy and immunology as well as pediatrics and leads the allergy division at Bryn Mawr Medical Specialists Association in Narberth, Pennsylvania. Data from adults supports this.
Asthma, for example, affects 7.3 percent of boys and 5.6 percent of girls, but the numbers flip-flop with age, to 6.2 percent of men and 9.7 percent of women.
Seasonal allergies (or allergic rhinitis, sometimes called hay fever) follow a similar trend. Boys are more likely to have seasonal allergies than girls (21.3 percent versus 19.8 percent, respectively).
But then in adulthood, the rate of seasonal allergies increases to nearly 30 percent for women, while staying nearly flat for men at about 21 percent.
Indeed, when it comes to any allergic condition there is data for, adult women have higher rates than adult men, Dr. Locke says. It isn't known for sure what causes these differences, he says. But because the shift in rates appears after puberty, hormones seem to play a significant role.
There are dozens of hormones in our bodies, but the sex hormones
estrogen and
testosterone seem to be the biggest players in allergies.
"In research, estrogen, which is typically higher in women, has demonstrated the ability to make the immune system respond more strongly to [allergens]," Locke says. "Whereas testosterone, which is typically higher in men, has the ability to calm some allergy cells." More research is needed to understand how each hormone may affect various allergic conditions.
This difference may potentially explain how males and females respond to allergens as they grow up, he says. And it could also at least partly explain why the hormone fluctuations that occur throughout a woman's life may affect allergy symptoms.
"When it comes to periods, some women notice their asthma gets worse a few days before and after their period starts," when estrogen and
progesterone levels are low, Locke says. "Their lungs become more sensitive and reactive during that time." Research has noted that across the menstrual cycle, there can be significant changes to asthma severity and lung function.
On the other hand, hormonal changes during the follicular and ovulation phases of the
menstrual cycle (when estrogen levels climb) can worsen allergic rhinitis (including seasonal allergies) and eczema.
About one-third of women with eczema or allergic rhinitis have worse symptoms during pregnancy, says
Maureen George, PhD, a professor of nursing at Columbia University School of Nursing in New York City and spokesperson for the Asthma and Allergy Foundation of America.
And some women with asthma experience worse symptoms during pregnancy, too.
But
menopause may offer some relief: Rates of allergic rhinitis tend to fall during this time, possibly due to declining estrogen levels.
And asthma rates drop, too, although using
hormone replacement therapy increases the risk for this condition.
On top of higher allergy rates, women tend to have more severe allergic reactions. The culprit is likely hormones again.
Research shows that female sex hormones may cause allergic reactions to be more common in women than men, says Payel Gupta, MD, a board-certified allergist-immunologist with Ease Allergy Clinic in Brooklyn and spokesperson for the American College of Allergy, Asthma, and Immunology.
Testosterone, on the other hand, helps protect against severe reactions, according to Dr. Gupta. "It does this by decreasing the amount of allergic-reaction-causing chemicals like histamine that are present in one type of allergy cell called a mast cell,” Gupta says. “Because these mast cells are less loaded up, the allergic reaction that follows is not as strong."
Research shows, for example, a connection between allergic diseases and low levels of testosterone and high levels of estrogen.
Whether certain
allergy treatments are more or less effective in men versus women is still under investigation, although there is some evidence that sex makes a difference.
"Men do appear to respond better to asthma therapy than women," for example, Dr. George says.
There aren't any studies showing that a certain medicine works better for one sex over the other, Gupta says. And treatment guidelines for asthma are the same for everyone, regardless of sex.
"However, because women tend to have more severe allergies on average, their symptoms can sometimes be harder to control," she says. "This might make it seem like the medicines aren't working as well for women, but it's really just that more severe disease is more difficult to treat in general, not that the medicine itself is less effective."
For this reason, programs such as the Oregon Clinic's Asthma in Women Program aim to provide specialized care to women with allergic conditions. Rather than following standard gender-neutral guidance, these programs take into account how factors like pregnancy and the fluctuating menstrual cycle impact allergies and asthma when providing care.
Research in this area has historically been lacking, but Gupta is hopeful that a clearer picture will emerge of how to better treat women's allergy symptoms in the future. "It is an important topic and has been ignored for a long time," she says.
