How long does it take for swollen glands in neck to go down after having a cold? what is considered normal?

Depends..: Many infections can linger even after sore throat has resolved. In general most reactive lymph nodes diminish in size after a couple weeks once the agent is gone. Mono, for example can take months....also sometimes lymph nodes get larger but dont go back to the original size. I suggest you see someone if it hasnt gone down 2-3 weeks after improvement in case you need to be examined or tested