I think my friend is becoming a drug addict?

me and him have started hanging out with some new partying friends. it started with ciggarettes, first he was just a social smoker but now he smokes like a chimney, and he constantly craves cannabis. i was okay with him just smoking weed but now he has suggested ding thinks like shrooms, lsd and ecstacy. he said in the past he would never smoke, then he said he would never do drugs that werent weed but he changed his mind there, he has said he will never inject heroin or snort cocaine but he may do, when he wants an even better high, or when lsd stops doing it for him. i worry for him, he also has an unhealthy obsession with the movie trainspotting