Can Catholics smoke and drink alcohol?

As long as it is done moderately, smoking is fine. If it is done so much as to harm a person’s health, then it is a problem.

“The virtue of temperance disposes us to avoid every kind of excess: the abuse of food, alcohol, tobacco, or medicine. Those incur grave guilt who, by drunkenness or a love of speed, endanger their own and others’ safety on the road, at sea, or in the air.”

The use of drugs inflicts very grave damage on human health and life. Their use, except on strictly therapeutic grounds, is a grave offense. Clandestine production of and trafficking in drugs are scandalous practices. They constitute direct co-operation in evil, since they encourage people to practices gravely contrary to the moral law. CCC 2290-2291

Drinking too is not bad in itself. The apostles drank alcohol and the wine used at mass is alcoholic. What matters, as with tobacco smoking is to ensure not to overdo anything. Overdoing these would become sinful mostly because it will harm the health we are supposed to protect.

“Even so, we have to take seriously the health danger of heavy tobacco consumption that modern medicine has established. What was moderate years ago may no longer be reasonably moderate, given what we know today. In any case, we should avoid the puritanical attitude toward smoking common in today’s society, where practically every form of real sin (and drug use) is promoted, and yet smoking is depicted as intrinsically evil.” – FR. HUGH BARBOUR, O. PRAEM