Rubefacients work by stimulating circulation in the skin and local tissues, creating a warming sensation that helps to alleviate discomfort from muscle aches, joint pain, or stiffness. They are often applied topically in the form of oils, creams, or liniments. Common examples include cayenne pepper (Capsicum annuum), ginger (Zingiber officinale), and mustard seed (Brassica nigra), which contain active compounds like capsaicin or volatile oils that promote increased blood flow. These substances are particularly useful in treating conditions such as arthritis, rheumatism, or muscle soreness.