I am a very occasional drinker and i drank 375 ml of whiskey the other day all neat with no water. is there any immediate liver harm in doing that?

Not from 1 time: Doing this once is highly unlikely to cause any damage to your liver. Your liver is a robust organ that has substantial physiologic reserve. You drank the equivalent of 8.5 standard drinks in a day, which is technically a heavy drinking day. If you drank that much on a regular basis, you would put yourself at risk for liver damage and developing alcoholism. http://rethinkingdrinking.niaaa.nih.gov