1 Poison ivy, poison oak, and poison sumac are plants than can cause an itchy rash upon contact. 2  A substance called urushiol, found in these plants, causes the rash. 3  The rash is not contagious.  The rash usually disappears in one to three weeks.
Common factors that can cause clogged ears are wax buildup, air flow blockage to the Eustachian tubes, pressure differences in the middle ear, and cold and sinus problems. Clogged ears can affect people of all ages, but is most common among children, especially when they have colds.
It's common to have plugged ears for a while after you've had a severe cold and it can also be caused by allergies. Fluid in the ear is more likely to be the cause of plugged ears in children because their auditory tube is smaller and naturally more horizontal than adults.