Make sure you check the storage minimum & maximum for your brand of syringes. They are designed to pull the medication into a vacum and expansion/contraction as can occur in checked luggage sitting out on the tarmac or unpressurized at 40,000 feet can damage them.

I would put them in your carry-on and have a copy of the prescription for them handy, presuming you're in a state where a prescription is required. If you aren't, ask your MD for a prescription anyway. You'll not likely be asked for it, but it's handy.