So a Catholic priest isn’t forbidden from consuming alcohol or other drugs, provided they were legal wherever he lives. However, he would get in trouble and perhaps defrocked if his behavior while imbibing did not reflect the morals and attitudes of the Catholic Church. I’ve seen in my childhood many a priest having a beer in the beer tent during the church festivals or enjoying wine or bourbon at a dinner with a church family. It’s expected of him to act responsibly at all times, so perfectly fine for him to do so if he can be a responsible adult about it.