In io tests can lead to an anaphylactic reaction, and therefore should be only administered by a trained allergist in the presence of resuscitation equipment.
And there's a theory that being too clean and bacteria-free – now we have soap, antibiotics and better sanitation – has lead to an increase in allergies.
14. Allergen Transfer: Even if individuals are not allergic to pets, they may carry allergens on their fur or paws, potentially causing discomfort to others who are allergic.