While JUUL heavily marketed its product as a safe alternative to traditional combustible cigarettes, despite lacking the data to support this statement, the often-overlooked ingredient, nicotine, should not be ignored. Particularly among users under the age of 26.
Because nicotine is not cancer causing in and of itself, its harmful effects are frequently unknown by the general public. The lack of awareness is also is due, in part, to the tobacco industry’s decades-long denial that nicotine is addictive. It was not until the Surgeon General issued a report on nicotine addiction in 1988 that there was a consensus that nicotine is highly addictive. Not only did the report conclude nicotine is highly addictive; it also concluded the physiological and behavioral processes that determine tobacco addiction are similar to those that determine heroin and cocaine addiction.
Nicotine poses particular harm to youth and young adult smokers. The human brain is not fully developed until age 25. Nicotine from e-cigarettes, like Juul, can lead to addiction, harm to brain development, and change the way the brain functions in users under the age of 26. It fosters addiction via the brain’s “reward” pathway. Nicotine, both a stimulant and a relaxant, affects the central nervous system; increases blood pressure, pulse, and metabolic rate; constricts blood vessels of the hair and skin; and causes muscle relaxation.
When nicotine is inhaled, it enters the bloodstream through membranes in the mouth and upper respiratory tract through the lungs. Once in the bloodstream, nicotine reaches the brain, binds to receptors, and triggers a series of physiologic effects in the user that are perceived as a “buzz” or “high” that can induce happiness, arousal, and reduction of stress and anxiety. These effects are caused by the release of dopamine, acetylcholine, epinephrine, norepinephrine, vasopressin, serotonin, and beta endorphin. With regular nicotine use, these feelings diminish over time and the user must consume increasingly larger amounts of nicotine to achieve the same pleasurable effect.
Once the brain is addicted to nicotine, the absence of it causes compulsive, drug-seeking behavior. It also causes withdrawal symptoms, which include but are not limited to suicidal ideation, anxiety, depression, irritability, mood swings, stress, difficulty concentrating, restlessness, headaches, insomnia, heart palpitations, and tremors. Nicotine affects neurological development in adolescents, and exposure to nicotine during adolescence produces an increased vulnerability to nicotine addiction.
Adolescent nicotine addiction causes “substantial neural remodeling,” including those parts of the brain governed by dopamine or acetylcholine, which play central roles in reward functioning and cognitive function. Adolescent smokers are found to have weakened neural responses including “diminished sensitivity to non-drug rewards.” Other brain changes from nicotine include increased sensitivity to other drugs and heightened impulsivity. “Brain imaging on adolescents suggest that those who begin smoking regularly at a young age…perform less well on tasks related to memory and attention compared to people who don’t smoke.”
Brain imaging studies of adolescents who began smoking at a young age also showed markedly reduced activity in the prefrontal cortex of the brain, an area critical for a person’s cognitive behavior and decision making, leading to increased sensitivity to other drugs and greater impulsivity. In short, nicotine use among youth and young adults can affect a child’s attention, memory, and cognition; and nicotine likely underlies the aforementioned impairments in attentional and cognitive function. Youth e-cigarette smokers report feelings of restlessness, irritability, heightened cravings, and anxiety. A 2016 Surgeon General’s report found youth use of nicotine in any form, including via Juul and other e-cigarettes, is unsafe, causes addiction, and can harm the developing adolescent brain.
Another reason Juul poses a unique threat to teens is its patented formula of nicotine. While other brands use a chemically modified form called “freebase nicotine,” Juul uses “nicotine salts” that more closely resemble the natural structure of nicotine found in tobacco leaves. This makes the nicotine more readily absorbed into the bloodstream and makes the vapor less harsh so that it is easier to inhale more nicotine for longer periods of time.
In addition to this patented formula, Juul pods contain a greater amount of benzoic acid, 44.8 mg/mL, compared to other e-cigarette brands, which are in the range of 0.2 to 2 mg/mL. According to the Center for Disease Control and Prevention (CDC), benzoic acid is known to cause coughs, sore throat, abdominal pain, nausea, and vomiting if exposure is constant, which is the case when using a Juul. This is due to how Juuls utilize the properties of benzoic acid to increase the potency of the nicotine salts in its e-liquid.
Whether the cognitive deficits associated with nicotine use are lifelong or can be reversed with discontinued use remains to be determined. What we do know is that the brain of adolescents reacts differently to nicotine exposure than that of adults. Given that a youth’s successes or failures during adolescence can forever change the trajectory of one’s life – engaging in criminal behavior, using or abusing other drugs in addition to nicotine, substantial decreases in academic performance, etc. – it is important that the public, including youth, their parents, and teachers, know the risks associated with Juul and the significant impacts it can have on one’s life and relationships.
 The Health Consequences of Smoking: Nicotine Addiction (USDHHS 1988).
 Neal L. Benowitz, Pharmacology of Nicotine: Addiction, Smoking-Induced Disease, and Therapeutics, 49 Annual Review of Pharmacology and Toxicology 57 (2009); Mariam Arain et al., Maturation of The Adolescent Brain, 9 Neuropsychiatric Disease and Treatment 449 (2013).
 Erin Brodwin, An E-Cigarette with Twice the Nicotine of Comparable Devices is Taking Over High Schools – and Scientists are Sounding the Alarm, Business Insider (April 30, 2018), https://www.businessinsider.com/juul-e-cig-vaping-health-effects-2018-3
 Musso F, Bettermann F, Vucurevic G, et al. (2007). Smoking impacts on prefrontal attentional network function in young adult brains. Psychopharmacology. 2007;191(1): 159-169. https://www.ncbi.nlm.nih.gov/pubmed/16937098
 E-Cigarette Use Among Youth and Young Adults (USDHHS 2016).
 Piasecki TM, Hedeker D, Dierker LC, Mermelstein RJ. Progression of nicotine dependence, mood level, and mood variability in adolescent smokers. Psychol Addict Behav. 2016.
 E-Cigarette Use Among Youth and Young Adults (USDHHS 2016).
 Centers for Disease Control and Prevention. Safety material data sheet: Benzoic acid. https://www.cdc.gov/niosh/ipcsneng/neng0103.html