How much worse can hepatitis c be when there is existing liver damage from alcoholism and drug abuse?

Much worse: Typically hepc will damage the liver without any other factors. However, if there is alcohol or additional toxins the damage is more exponential than additive. In otherwords it will muliply the damage from one agent alone rather than just add to it.

3x worse : Alcohol is fuel on the fire of hepatitis c related liver disease. One of the most important interventions someone can do to improve their liver health, besides antiviral treatment, is stop drinking. It is never too late to stop and slow down the damage. It is important to discuss alcohol use with a doctor so they know there is an increased risk of cirrhosis (3x higher than those who do not drink).