Originally Posted by MSY-MSP

Well my experience with this is mixed. The case by case means that the allowance of any non-prescription medication is purely at the discretion of the screeners. What they are supposed to do is determine if the non-prescription medication is "essential" for the trip. The term "essential" is vauge to say the least and requires the agents to act as a Dr. In theory all the agent is supposed to ask is "What is this for?" If it deals with any part of you, and it is likely you would need the item during the flight, they should allow it. However, as we all know not all TSA agents follow this approach.

One of the problems, and particularly so with saline solution/lens cleaner is that the agents know that sizes smaller than 4oz are available. I think this is why many try to deny them through the checkpoint. In the end it is allowed, but is a hassle. The way I have combatted this is by having my OD/MD prescribe the cleaner and get a prescription label on the solution from the pharmacy. If it has a prescription label on it, TSA cannot question the purpose of the item, and can only screen the item.