As of right now I have been hodling few thousand worth bitcoin, I didnt cash it out. But because of price drop, I am in loss. How do I file this on tax return in US?
If you just bought and held BTC and have never sold it, no taxable event has occurred yet. Nothing is reportable on your taxes yet.
Tax liability usually doesn't come into play until you've
realized a capital gain or loss by selling. As mentioned above, a loan isn't reportable as income either.
It sounds like you won't need to report anything Bitcoin-related on your 2018 tax return. I'm not a lawyer and you should probably ask a tax advisor just to be sure, though.