Pennyroyal, a plant with smooth oval leaves, has been used since ancient times as a cough remedy and digestive aid, as well as a flea repellent. The strong aroma of its infusion acts as a decongestant and possibly as an expectorant, helping to remove excess mucus from the lungs; it is therefore useful for coughs. While the dried herb is safe in recommended doses, the oil of the pennyroyal plant should not be ingested, since even small amounts of it are toxic.
Over the counter:
Pennyroyal is available as tinctures and as dried leaves and flowers.
Tea: 1 to 2 tsp. dried leaves steeped in 1 cup boiling water for 10 to 15 minutes, or 1 tbsp. dried herb mixed with 1 cup warm water.