What is a Rubefacient?
These are herbs that when applied to the skin, in some form, will cause a gentle and localized increase in surface blood flow (vasodilation). This usually shows as a reddening of the skin. They can vary in potency, and in older medical texts get sub-divided by this power. A vesicant produces actual blistering. They are used mostly today to ease the pain and swelling of arthritic joints.
How Rubefacients Work
Their value is based on bringing blood to the area involved. This has two broad benefits. First the increase in flow through will aid in the cleansing and nourishment of the affected part. This mimics the process of inflammation but is less painful as the biochemical basis is different. The other area of use, though less favoured today, is drawing blood from deeper parts of the body into the skin which may relieve visceral pain. By using rubefacients on different parts of the skin, different internal areas may be affected.