Pennyroyal. safety? uses: colds, pneumonia, breathing problems, stomach pains, gas, intestinal disorders, liver, gallbladder. womens issues used to control muscle spasms, cause sweating, and increase urine production. used as stimulant and to counteract weakness. applied to the skin to kill germs, keep insects away, treat skin diseases, topically for gout, venomous bites, and mouth sores; and as a flea-killing bath. oil used flea repellent; fragrance detergents, perfumes, and soaps.