Pill box is fine. They don't check medicines or prescriptions for domestic flights.
TSA and all law enforcement agencies want all medicine in original containers. This is because they can tell what things are right away. However, if you had medication in a pill container and they really wanted to know what it is, they have ways of testing it if they are going to make a big deal about it. I've taken medicine and pills (ibprofin) through a tsa checkpoint in a different unlabeled container and they said nothing, so it can come down to what agents are working the gate. Hope that helps.
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