Traveling with vape pens on domestic flights requires understanding TSA regulations. Vape pens and e-cigarettes are allowed in carry-on luggage but prohibited in checked bags due to lithium battery risks. Ensure your device is powered off and stored securely to prevent accidental activation. Liquids, including e-juice, must follow the TSA’s 3-1-1 rule: containers of 3.4 ounces or less in a clear, quart-sized bag. Check airline policies, as some may have stricter rules. For THC vape pens, federal law prohibits cannabis products on flights, even in states where it’s legal. Always research your destination’s laws to avoid legal issues. Keeping your vape pen clean and labeled ensures a smoother security process.