Blog Post Written by Mike Pelyhes PharmD Student at Cedarville University.
Caffeine is a common CNS stimulant used by up to 90%(1) of adults in the United States. It is currently the only CNS stimulant that is approved for nonprescription use by the FDA. Caffeine is generally considered safe and effective for the treatment of occasional drowsiness and fatigue, but it should never be used as a replacement for sleep. If you find yourself struggling with occasional drowsiness and fatigue, then evaluating sleep habits is a great place to begin. For starters getting 7-8 hours of sleep can do wonders(2). Additionally, going to bed and waking up at the same time everyday can help your body by allowing it to adjust to a normal sleep pattern. If caffeine is still desired; perfectly valid options include coffee, tea, diet soda, or caffeine pills. In general it is best not to ingest more than 200 mg on a regular basis. That includes being careful of a tall (12oz) Starbucks coffee that packs a whopping 260 mg of caffeine per cup(2). It is also wise to be aware that chronic caffeine use, particularly in high doses, can cause tremors, elevated blood pressure, headaches, and irritability. Additionally, if you have problems with uncontrolled high blood pressure or have had heart problems then caffeine may not be a good product for you to use.
In news articles published by the Huffington Post and NPR a new form of taking caffeine is being introduced. This caffeine form is a topical spray that is meant to be applied to the skin on the side of the neck where the carotid artery and jugular vein run. This spray is designed for the caffeine to be absorbed through the skin and directly into the bloodstream.Theoretically this results in a higher amount of caffeine actually reaching the bloodstream compared to if the caffeine was ingested orally(3) The product designer is Ben Yu, a Thiel Institute Fellow. Yu claims that because the caffeine is absorbed right into your bloodstream that it acts quicker (within 7-10 minutes)(4) than orally ingested caffeine, and that it avoids the “energy” bursts and crashing effects of normal caffeine ingestion. Additionally, Yu is hoping to get this product through to the public as a dietary supplement without the stringent FDA regulations that other caffeine products such as No Doz have gone through.
While the Huffington Post and NPR report this as exciting news for caffeine users, I would recommend caution with this new way to take caffeine. As per Yu’s own admission, rigorous studies on the safety and efficacy of this product have not been completed. Caffeine can have dangerous effects on blood pressure and there is limited data on the use of topical caffeine products, and little to no data regarding the actual enhanced absorption claims by Yu. However, a study on topical caffeine application for psoriasis treatment found the only clinically significant common side effect reported for topical caffeine use was a mild irritation(5) on the skin caused by the caffeine. Another study on the effect of hair follicles on the absorption of topical caffeine into the skin found hair follicles to have a clinically significant effect on increasing caffeine absorption into the skin(6). While this study did not measure absorption into the bloodstream, it did show that caffeine can be absorbed into the skin in as little time as 5 minutes. Therefore further study on topical caffeine absorption is likely needed.
Due to lack of data on topical caffeine use in a self care setting or even under the care of doctors, I would not recommend this product to my own patients. There is limited data on the effects of topical caffeine that is rapidly absorbed directly into the bloodstream. With a time of absorption up to 5 times quicker(2) than orally ingested caffeine. There is also evidence of skin irritation from topical caffeine use Additionally, since oral ingestion of caffeine is shown to have absorption rates as high as 99%(7), the claims of superior absorption of topical caffeine are perhaps misleading, wrong, or poorly explained. I would personally recommend oral caffeine intake as it has been well studied. Its benefits and side effects are well known, and it already comes in a wide variety of choices that can fit many tastes.
Here are some things to consider if you are interested in this product. Is the possibility of mild skin irritation worth it for a new way to get a caffeine fix? Is this product necessary with the wide variety of oral products already available? Is it something that you think you would find more convenient than already available alternatives? Are you concerned over the apparent lack of clinical research on the product?
 Frary CD, Johnson RK, Wang MQ. Food sources and intakes of caffeine in the diets of persons in the United States. J Am Diet Assoc. 2005;105:110-3
 Kirkwood, K., & Melton, S. (2012). Insomnia, drowsiness, and fatigue. In D. Krinsky (Ed.),
Handbook of Nonprescription Drugs: An Interactive Approach to Self-Care (17 ed., pp. 876-879). Washington, DC: American Pharmacists Association.
 Gates, S. (2013, August 21). ‘sprayable energ’y caffeine spray will perk you up without the aftertaste. Huffington Post. Retrieved from http://www.huffingtonpost.com/2013/08/21 /sprayable-energy-caffeine-spray_n_3790271.html
 Hu, E. (2013, September 11). Coming soon: A jolt of caffeine you can spray on your skin. NPR. Retrieved from http://www.npr.org/blogs/alltechconsidered/2013/09/11/221364843/coming -soon-a-jolt-of-caffeine-you-can-spray-on-your-skin?ft=1&f=1007
 Vali A, Asilian A, Khalesi E, Khoddami L, Shahtalebi M, Mohammady M. Evaluation of the efficacy of topical caffeine in the treatment of psoriasis vulgaris. The Journal Of Dermatological Treatment [serial online]. 2005;16(4):234-237. Available from: MEDLINE with Full Text, Ipswich, MA. Accessed September 24, 2013.
 Trauer S, Patzelt A, Otberg N, Knorr F, Rozycki C, Balizs G, Buttermeyer R, Linscheid M, Liebsch M, Lademann J. Permeation of topically applied caffeine through human skin – a comparison of in vivo and in vitro data. Br J Clin Pharmacol. 2009;68:181–6
 Anthony Liguori, John R. Hughes, Jacob A. Grass, Absorption and Subjective Effects of Caffeine from Coffee, Cola and Capsules, Pharmacology Biochemistry and Behavior, Volume 58, Issue 3, November 1997, Pages 721-726, ISSN 0091-3057, http://dx.doi.org/10.1016/S0091-3057(97)00003-8.
Keywords: Absorption; Caffeine; Coffee; Cola; Subjective effects