When I spoke with my pdoc about benzos and alcohol, he told me that if you've taken a benzo within about 3 hours then you can expect the effect of the alcohol to be doubled. But, it varies person to person, just as the effects of benzos alone or alcohol alone vary by person.

I'd suggest talking with your pdoc about what a safe amount of alcohol is when taking benzos. My pdoc was very open to the discussion and appreciated me asking about it.

Personally, I'm very sensitive to alcohol, and dislike feeling buzzed, so I made the choice not to drink alcohol at all while on meds.