Evaluation of the Electronic Cigarette Withdrawal Syndrome

Inclusion criteria: 1. 21-55 years old 2. good general health as reviewed by study medical team 3. vital signs in normal range as reviewed by study medical team 4. negative urine test for illicit drug use (excluding THC) and negative breath alcohol test 5. daily use of a nicotine-containing e-cigarette for at least 6 months 6. no regular use of other tobacco products (e.g., smokeless products) for at least 6 months 7. urine cotinine \>100ng/mL (i.e., recommended cutoff for confirming current nicotine use) 8. exhaled breath carbon monoxide (CO) \<6ppm 9. Penn State E-cigarette Dependence (PSED) score \>=4, indicating mild dependence or greater 10. have an interest in reducing e-cigarette use Exclusion criteria: 1. psychoactive drug use (aside from cannabis, nicotine, alcohol, caffeine) in past month 2. current use of over-the-counter (OTC) or prescription medications that may impact safety 3. use cannabis \>2 times per week 4. history of or current significant medical condition that would impact participation or safety according to the study investigators and medical staff 5. current psychiatric condition or substance use disorder (aside from tobacco use disorder) that would impact participation or safety according to the study investigators and medical staff 6. enrollment in another trial 7. positive pregnancy test 8. currently using a nicotine/tobacco cessation product 9. seizure disorder or traumatic brain injury (TBI)