I have been on Cymbalta for 8 days. Read many bad reviews. Will I have withdrawal after only 8 days?

Likely not after 8 days. I had a two month nightmare coming off that drug. I could not focus enough to have a conversation. Forgot where I was driving. Even cold sober caught myself peeing in my kitchen garbage can.

What dose were you on?

In theory you should not feel withdrawals, but everyone is different , there are people more sensitive than others to these type of medications (SSNRI) that affect your brain chemistry, so it is relative, knowing what dose you were on is important.