Do Women Have More Severe Allergic Reactions Because of Estrogen?

Allergic reactions that are caused by factors such as medications, insect bites or foods are referred to as anaphylaxis. Such allergies can be very severe, and even life-threatening. For a long time, scientists and doctors have known that females suffer worse allergic reactions than males do, and are more prone to such reactions. The reason why, however, has been elusive up until now. A new study, however, points to a surprising possibility: estrogen.


Anaphylaxis is an immune response triggered when the body senses the introduction of a foreign substance, generally from food, stings or bites, medicine, or the like. The immune cells, especially mast cells, cause tissues to swell, which creates the allergic reaction.

Allergies and Estrogen

Estrogen refers to a group of hormones that help to regulate sexual development and reproduction. These hormones are far more prevalent in women than in men and are directly associated with puberty and the menstrual cycle. The recent study indicates that estrogen is directly involved with immune-response to allergens.

Of Mice and Men

The study, funded by researchers from the National Institute of Allergy and Infectious Diseases, which is a section of the National Institutes of Health, shows that certain immune cells release chemical enzymes which can cause rashness and reddening skin. These can also cause respiratory issues and even heart attack.

By inducing anaphylaxis in mice, the study authors were able to check for differences in reaction between the sexes. By introducing histamine and immunoglobulin compounds, the team could trigger allergic reactions and monitor vital signs such as body temperature, lung weight and mast cell mediators.


The study indicated that females had measurably more severe and longer anaphylactic reactions. These reactions seemed to be due to a form of estrogen called estradiol. This chemical influences blood vessels and creates heightened levels of activity in the enzyme that creates anaphylactic reactions. This enzyme is called endothelial nitric oxide synthase.

Blocking eNOS

When the team blocked the activity from eNOS, however, they discovered that the gender differentiation became nonexistent. Further, female mice showed far reduced symptoms, leveling off to the same severity as males.

The Importance of the Findings

The study is still a preliminary finding, researchers say. More research needs to be conducted to establish whether humans will show the same reactions as mice. If the findings hold up, however, they could create new avenues for treating allergies both in a preventative form and as they occur.

At very least the initial study as it stands sheds a lot of light on how important it is to account for gender when conducting medical experiments.

Do you suffer from food allergies or reactions to insect stings? If so, what are your thoughts on the study? How do you treat your allergies? If you have any thoughts on this story and whether it represents a breakthrough, we are eager to hear your thoughts. Leave us a comment below, and let us know! We look forward to it!

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