... color, stiffness, and thickness, but does not improve itching, pain, or scars, in people who have had portions of skin removed surgically ... oregano is taken by mouth for intestinal parasites, allergies, sinus pain, arthritis, cold and flu, swine flu, earaches, and fatigue. ... as for insect and spider bites, gum disease, toothaches, muscle pain, and varicose veins. Oregano oil is also used topically ...