GHB (gamma-hydroxybutyrate) is produced naturally in the human body in very small amounts. When taken as a recreational drug, and especially when taken in combination with alcohol or other drugs, GHB can be extremely dangerous. GHB is a central nervous system depressant.
International flights always allow carry-on luggage, but each airline has its own restrictions as to quantity, size and weight. Some international carry-on policies restrict bag weights to 11 lbs. or less, while domestic flights rarely have a weight limit.
There are no bag fees for international itineraries except Canada. United, Delta, Continental and US Airways recently announced $5 increases in checked-bag fees paid at the airport, to $20 for the first and $30 for the second. Those other carriers left the fees at $15 and $25 for people who pay the charges online, but American doesn't offer the online option.