The purpose of this research study is to find out how different types of electronic cigarette/vape e-liquids with differing sweetness and forms of nicotine affect blood nicotine levels, use behavior (how people puff), and how people feel.

In this study, participants will be asked to do the following:

1. After an initial screening visit, visit the Center for the Study of Tobacco Products 4 more times for approximately 3-hour study visits.
2. Before each visit, abstain from all tobacco products (cigarettes, e-cigarettes/vapes, cigars, and hookah/waterpipe) for at least 12 hours.
3. Allow researcher to take blood pressure readings (with blood pressure cuff on their arm) monitor their heart rate (with a device that attaches to their finger), and allow a nurse to insert an IV catheter into their arm that will stay there for the entire session. This catheter will be used to draw blood periodically (less than 1 tablespoon per sample, 5 samples per visit).
4. During each session, participants will respond to several questionnaires to measure how they feel before and after they use an e-cigarette.
5. In each session, use an electronic cigarette provided by the study team at two separate times. After using the e-cigarette two times, participants will be offered the opportunity to use their own e-cigarette or cigarette.

Inclusion Criteria:

• healthy (determined by self-report)
• between the ages of 18-65
• willing to provide informed consent
• use cigarettes, e-cigarettes, or both
• able to attend the lab and abstain from tobacco/nicotine as required and must agree to use designated products according to study protocol

Exclusion Criteria:

• women if they are breast-feeding or test positive for pregnancy (by urinalysis) at screening
• existence of any condition contraindicated for this study protocol as determined by study leadership

Some study details about the eligibility criteria are purposely omitted at this time to preserve scientific integrity. Full details will be posted at the conclusion of the study.