Sulfur was often burned or boiled and the fumes were inhaled or applied to the skin to disinfect the body. The belief was that sulfur would help kill the bacteria and viruses that were causing the disease. Sulfur was also sometimes ingested and it was believed to help improve the body’s overall health and immunity. It could also be applied topically as an ointment or poultice. Sulfur can be highly toxic in large doses, and prolonged exposure to sulfur fumes can cause respiratory problems and other health issues. It is still used in some medical treatments, such as the treatment of acne and skin conditions, but it is not used as a treatment for the plague or other infectious diseases.