Caffeine is a central nervous system stimulant that temporarily wards off drowsiness and boosts alertness and energy.

Camellia Sisensis .

Capsaicin is used in several skin preparations and is used to relieve pain. It is available in the market in various forms such as ointments, creams, gels, liquids, lotions, sticks and pads under marketing names such as Capsagel, Zostrix, Arthricare for Women and Icy Hot Arthritis Treatment. A very astonishing fact is that capsaicin happens to be the active part of chili peppers. Though it is an irritant producing burning sensation on any tissue that comes in contact with it, it depletes substance P. Substance P transmits impulses of pan to the brain. It relieves pain due to diseases such as osteoarthritis, diabetes neuropathy and rheumatic arthritis. Capsaicin has not had any drug interactions till date. But this does not means that it can never have any interaction with any other drug. It is always best to confirm with your doctor if you really need to use capsaicin. Also, it is best to use this drug only in specified quantities.

Polyphenols.

Yohimbe is a tree that grows in different parts of Western Africa. Active compounds called alkolids are present in its bark with Yohimbine being the principal alkaloid. Yohimbe bark extracts are available in health food outlets. You can also buy it online. These extracts are promoted as a product that increases sex drive and for the treatment of erectile dysfunction. However, there is proof of their effectiveness. Most studies are concerned with the drug Yohimbine and not herbal extract Yohimbe. The side effects of Yohimbe include anxiety and dangerous increase in blood pressure.