Cayenne is a hot pepper which has had a long history of use in herbology. Its active ingredient is capsaicin. When taken internally it can warm the body, raise metabolism, improve weak digestion and increase circulation.
When used topically in prepared products standardized for capsaicin activity (0.025-0.075%), it temporarily depletes substance P, required for pain signal transmission. The cream is typically applied to the painful area(s) tid - qid. Besides causing a mild burning for the first few applications (or severe burning if accidentally placed in sensitive areas, such as the eyes), there are no side effects from use of the capsaicin cream. As with anything applied to the skin, some people may have an allergic reaction to the cream, so the first application should be to a very small area of skin. When using cayenne, wash your hands before touching your eyes. Use cayenne only on unbroken skin; if irritation occurs, discontinue use.
It sometimes takes more than a day or two for the benefit to kick in, which is when the burning sensation stops. So spending a little more time building up a tolerance to the burning sensation might be one way to make the discomfort a bit more bearable. It takes something with true detergent action to get this material off your skin -- a mild baby shampoo or dish liquid is your best bet -- and a wipe-down with rubbing alcohol won't hurt either. If you can tolerate it on your skin for at least 15 minutes you will get some benefit even if you have to wash it off later.
Very high intake of cayenne internally may inflame ulcers instead of treating them, but this amount is difficult to achieve with sensible intake. People with ulcers, heartburn, or gastritis should use any cayenne-containing product cautiously as it may worsen their condition. It is interesting to note that ulcers have been treated with cayenne.
Cayenne often contains 40,000 heat units per capsule of 450mg. A typical dose is 1-2 capsules (tincture 5-15 drops) 2 or 3 times daily before meals.