We have no luck with syringes at all - but the spoon works well. And the post-medicine chocolate bribe too.
If it is gluggy medicine then adding a little water may help too.

A lot of this is about control - your little one probably resents being forced to do something, especially something yucky. Try putting the medicine on a very big spoon on the table, and putting the treat next to it and telling him that when he has swallowed all the medicine he can have the treat. And agree with him that its yucky - we call DS's antibiotics "horribus medicine" because that's what he christened it.

I had a similar problem with my DS and teeth cleaning. I used to have to swaddle him in a blanket and sit on him to clean his teeth. But now he is big enough to "do it himself" he does it, and then I just do a quick clean afterwards - no major fights any more.