Whenever I catch a cold, I always get a runny nose.
Literal
Cold [object-を] catch-[if-と] I [topic-は] always runny-nose [subject-が] comes-out.
風邪を引くと marks a natural habitual consequence: 'whenever I catch a cold.' いつも鼻水が出る means 'a runny nose always comes out.' 鼻水 literally means 'nose water.'