Years ago, when I was battling issues with depression and anxiety, I asked my therapist at the time if she thought it was a bad idea for me to drink alcohol.
This counselor was a psychologist, not a psychiatrist. So she wasn't a medical professional.
She said that I would have to ask my psychiatrist if it would interact with the psychiatric medications that I was on at the time.
But she went on to say that either way it would likely be a bad idea for me to drink because alcohol is a depressant and could increase the likelihood that I could become depressed again. She also said that alcohol consumption can make impulsive thinking worse as well. And making compulsive decisions were also a problem for me back then.
Hence, after hearing her response, I elected not to start drinking again ( I drank a little bit years before then when I was a teen).
So if you have mental illness and are on psychiatric medication(s), it may be a good idea to ask your shrink if it's a bad idea for you to drink if you're thinking about drinking in the future, especially since alcohol might interact with the pills you're on.