Does the second use of a teabag contain less caffeine?

Yes, the second use of a teabag typically contains less caffeine than the first infusion. Most of the caffeine is extracted during the initial steeping, so subsequent brews will yield diminishing amounts. However, the exact caffeine content can vary depending on factors such as the type of tea and steeping time. Generally, while the second brew may have reduced caffeine, it will still retain some flavor and beneficial compounds.