often a suspected feather allergy is actually an allergy to dust mites, whose proliferation is encouraged on and around feathers. (Dust mite allergy is actually the most common allergy, while feather allergy is not very common.)
The most common kind of allergic reaction to feathers that you might experience is hay fever, known in the medical community as allergic rhinitis. Symptoms of hay fever include puffy, itchy, watery eyes, runny nose, nasal congestion, sneezing, cough, post-nasal drip, sinus pressure, facial pain, allergic shiners (swollen, blue skin under the eyes), itchy mouth, nose or throat and decreased sense of taste or smell.
https://www.mayoclinic.org/diseases-conditions/dust-mites/symptoms-causes/syc-20352173
