Injuries, tumors or infections can cause a blocked tear duct in adults, according to Mayo Clinic. Partial or total obstruction in the tear drainage system causes blocked tear ducts. The condition is more common in newborns in whom the tear duct may not be fully developed at birth, states MedlinePlus.
Symptoms include excessive tearing, redness, and dried or crusty tears on the face, states MedlinePlus. Adults frequently need medical attention to clear up a blocked tear duct, while in newborns the condition normally resolves itself within the first year of life. If there is damage from the blockage, a doctor may perform minor surgery to place a tiny stent to re-open the duct passage.