According to http://apps.tsa.dhs.gov it says the following:
You may carry liquids, gels and aerosols in your carry-on bags only if they adhere to the 3-1-1 rule: containers must be 3.4 ounces or less; stored in a 1 quart/liter zip-top bag; 1 zip-top bag per person, placed in the screening bin. Larger amounts of non-medicinal liquids, gels, and aerosols must be placed in checked baggage.
Medically required liquids, such as baby formula and food, breast milk and medications are allowed in excess of 3.4 ounces in reasonable quantities for the flight. It is not necessary to place medically required liquids in a zip-top bag. However, you must tell the Transportation Security Officer that you have medically necessary liquids at the beginning of the screening checkpoint process. Medically required liquids will be subjected to additional screening that could include being asked to open the container. We recommend, but do not require, that medication be labeled to facilitate the security process. Many airports have designated lanes for families and individuals with items requiring additional assistance with screening.
The problem is, I've been able to do this once (domestic), however the second time I had it taken away (international).
The time that I had it taken away was when I actually told the dude I had it in my bag, they removed it, kept it, and told me it was not allowed.
Is this up to the discretion of the TSA officer, or is it due to the fact I was in the international terminal versus the domestic terminal? I don't really see the difference.