Urticaria is a common skin disease that is characterized by itchy and edematous plaques that appear suddenly and disappear spontaneously within the same day. About half of all cases of urticaria in children are attributed to infections, and they usually do not require routine diagnostic tests. An eight-year-old girl who presented with acute urticaria had signs of respiratory tract infection, and urticaria did not respond to antihistamines. A subsequent test revealed a Mycoplasma pneumoniae infection, which was treated with azithromycin. In patients presenting with acute urticaria together with signs of respiratory tract infection, the possibility of Mycoplasma infection should be considered in the differential diagnosis, especially if urticaria does not respond to antihistamine therapy

Keywords: urticaria, Mycoplasma pneumoniae, antihistaminic, azithromycin