It is unlikely cat or animal dander or allergy
to the new detergent as this happens randomly.
is the diagnosis and underlying thyroid dysfunction
plays a role in aggravating the urticaria, although the exact mechanism remains uncertain.
Thyroid autoimmune disease
may reflect that the urticaria you are having is autoimmune for which a long period of antihistamines (avoid sedative ones) are required to control the urticaria.
Also you must get a TSH, fT3, fT4 checked if there has been a change in the thyroid medication dose (presuming you are on Eltroxin
) and also otherwise as underactive or overactive thyroid can aggravate the urticaria.