Caffeine is of course a major component of every day drinks such as tea and coffee and is also included in Estrin-D. It is claimed that over 70% of the American population take more than 300 milligrams daily. As well as in familiar drinks it is used in energy drinks such as Red Bull as well as in many over the counter analgesics and other medication. Medically it is a as trimethylxanthine, useful as a heart stimulant and it also works as a mild diuretic. It works in the same way as certain drugs, the amphetamines, cocaine, and heroin, all of which work on the action of the brain although in a milder way, and like them it is addictive.

Ginger Root- Ginger is a spice which originated in Asia, where it is grown primarily in India and the Southeast of Asia. Currently it is used all over the world for culinary purposes. Several other uses, besides that of a spice, have been encountered, like in Ginger Ale, ginger tea, but also ginger beer. Gingerbread is perhaps the most popular example of ginger use, but historically it has been labeled as a stimulant and a carminative. Indonesia traditionally uses herbal preparations with ginger, which is supposed to reduce fatigue and help control all kind of digestive problems. Ginger is also known to help with morning sickness and is an ingredient in motion sickness remedies. Nausea in many forms, including chemotherapy, is treated with ginger as well.

Green Tea Extract increases energy expenditure and affects fat oxidation, which therefore promotes weight loss by increasing the body's metabolism.

Guarana is a climbing plant of the Sapindaceae family native to the Amazon basin. Guarana is best known for its fruit and seeds. Guarana extracts contain naturally high amounts of caffeine which the plant uses in defense against pathogens. Its extracts are a natural and abundant source of caffeine in most parts of the world. It is added to soft drinks, herbal tea, energy shots and used in capsules. The extracts have a positive effect on cognition and they also increase memory retention and physical endurance. A 2007 study on human pilots showed its positive effects on memory, alertness and mood. It is also reported to have antioxidant and antibacterial effects.

Kola Nut, bitter brown seed that contains caffeine. Once used to make cola soft drinks, Kola Nut has been replaced by artificial flavourings in most beverages.

Some Unknown Ingredients, which is a common practice for many supplement manufacturers. They use ineffective common ingredients and trademark their name for them to disguse the actual low quality ingredient contained.

Yerba Matte- The plant of the yerba maté, as yerba matte is actually called, is a small tree or a shrub which can grow up to a size of fifteen meters. The leaves and twigs have traditionally been used to brew a tea like concoction, which is still a very popular social beverage in South America. Yerba maté contains alcaloids that are very similar to caffeine, commonly referred to as xanthines, but also elements like manganese, magnesium and potassium. The main difference between yerba maté and coffee, for instance, is the effect it has on muscle tissue, where it appears to relax smooth muscle tissue, but stimulate heart tissue and that is why it is used in Estrin-D. In other studies, yerba maté was found to work as a monoamine oxidase inhibitor, thereby professing antidepressant qualities.