daynejule, take a look at this:
http://blog.tsa.gov/2011/08/traveling-with-medication.htmlThere should be no issues from a TSA perspective. Contrary to popular belief, TSA screeners are not malicious idiots and perverts with a single-minded mission to make travelers' lives miserable, nor are the screening rules and regulations deliberately difficult to navigate.
If you need the meds on the flight, you will be able to take them on the flight. If you have more than is allowable in terms of liquid volume, or if you don't actually need it on the flight with you, just pack your meds in a suitcase and check them instead of carrying them onboard.
And as Cindy stated, check with the country you're going to for their regulations on what documentation you need, although it's unlikely to be an issue if you are carrying the medication legally and it's in its original container with your name on it. But carrying a copy of your prescription and your doctor's contact info along with your passport would be advisable.
But yes, needles on a plane are not a problem if they are medically necessary.