According to a paper which appeared in The Journal of Allergy and Clinical Immunology, the female sex hormone estrogen can worsen allergic reactions in women.
Estradiol, a type of estrogen, enhances the activity and levels of the chemical which drives life threatening allergic reactions in women. Anaphylaxis, an allergic reaction triggered by food, medication or insect stings and bites is one such condition.
Researchers conducted experiments on mice. They found that female mice experience more severe anaphylactic reactions than males. When female mice were given estrogen-blocking treatments, the severity of their allergic responses reduced to levels seen in males.