Customize your care with Boiron single medicines for highly targeted relief. Natrum Sulphuricum 30C is a homeopathic dilution of Natrum Sulphuricum that relieves Bronchial Irritation Worsened By Humidity.The pellets melt in your mouth and can be taken on the go, no food or water needed. (BoironUSA.com) About Boiron: With more than 85 years of expertise, Boiron is a trusted brand that prides itself on quality manufacturing and responsible environmental practices. All products are made according to the highest standards of cGMP and formulated with HPUS ingredients for purity.