Consider issues. U get pin worms by putting egg contaminated fingers in the mouth. The eggs travel through, hatch & begin to live in your large intestines. Living pw's crawl out your anus &lay eggs. If you get an allergic rxn to the glue like stuff the eggs are laid in, it will itch a lot. Mature worms are visible, white, thredlike & about an inch long. Rx is so simple & free of side effects many just treat on suspicion.