The link between hormones and allergies haven't been well studied, but some small studies and anecdotal evidence suggest that your immune system can shift a bit in response to hormonal changes. Like nearly everything hormone-related, this affects people with menstrual cycles the most. "In women, the effect of hormones, such as estrogen, may lead to a worsening of their asthma during different times of the menstrual cycle," explains Bassett. Puberty, pregnancy, and menopause are also commonly times of allergic change—at least anecdotally, since few studies on the subject exist in the literature. Asthma symptoms definitely change during these shifts in hormonal balance, and female bodies experience more autoimmune diseases and immune responses generally, which seems to indicate that female sex hormones have a significant influence on the immune system.