Estrogen causes histamine release, its the drop in progesterone leading up to menopause that causes allergies and histamine response to increase, progesterone in its role of dampening the immune system helps with allergies, I found my allergies worsened leading up menopause and afterwards and not helped by being on estrogen.
"Hormones - including stress hormones
Rising estrogen levels have been associated with elevated histamine, and women might notice increased sensitivity and symptoms of histamine intolerance at different times in their monthly cycle. Periods of high estrogen link to sinus sensitivity to histamine. Environmental estrogens such as pesticides, agricultural growth hormones, and PVC in plastics may also activate histamine release. Conversely, histamine appears to stimulate estrogen levels as well and exacerbate symptoms. Diamine oxidase levels are much higher in the luteal phase of the menstrual cycle, theoretically reducing the risk of excess histamine during that phase.
The "stress" hormone cortisol appears to increase histamine in stomach and intestines in lab studies. Reducing stress can lower the amount of stimulating hormones that activate mast cells which release histamine and other factors of inflammation"
from
http://www.rlcure.com/histamine.html After seeing Allergy Specialist (NHS) he spent quite a times explaining about my rise in mast cells and what can cause it.