Some constructive possibilities that come to mind for my one-member (myself, only) and non-Christian and non-proselytizing Progressive Prohibitionist Religion, a public-service-minded "Honor Society" religion with very stringent membership-eligibility requirements:
---You could politely comment to him that you really enjoy associating with him as a human being, and you hope that he currently feels well liked and loved by many other persons during this particular period of his life.
--You could politely mention to him that you sense that he is not looking well that day, and you could then politely ask him if he has considered arranging for an appointment with a first-rate medical physician to examine himself as soon as possible, such as in the emergency room of a hospital?
--You could discreetly ask him in a polite manner if he has recently changed his brand of cologne or underarm deodorant that he is using.
This question, while it may come across to him as sly or excessively intrusive, will at least call his attention to your being aware that he may currently be victimized by consumption of a life-ruining and flagrantly illegal illicit drug on at least one recent occasion.
That possible victimization would be applicable regardless of whether it was inflicted on him by others against his wishes or through self-inflicted victimization for which he himself is primarily responsible for that choice he made, of at least one form of an often-fatal and always-medically-injurious illicit drug.
---You could politely mention to him that you have read very alarming factual accounts about individuals who died from having sustained an overdose of an illicit drug or from having consumed an illicit drug. Is he aware of that very tragic type of real-life outcome from consumption of an illicit drug?
--You could politely mention to him that individuals who have a reputation for NOT consuming any cocaine will find it much easier to make new friends with, or to go out on dates with, or to get married to, someone who is herself or himself a law-abiding and dependably civil and honest and kind lady or gentleman.
---You could volunteer to him that many people regard consumption of the illicit drug cocaine as a form of anti-social activity that invites shunning of that individual by honorable and law-abiding persons.
--You could volunteer to him that individuals who become illicit-drug addicts are probably 100 times more likely to get disinherited by one or more of their parents, and to receive nothing from that parent's last will and testament and accompanying estate, than are individuals who lead illicit-drug-addiction-free lives.
--You could politely volunteer to him (if true, as it definitely is in my own case) that a "cocaine-theme" party you yourself were once present at as an invited guest for a matter of seconds without your having been informed in advance that there would be any illicit drug of any type at that so-called "party", or that the so-called motif of that so-called party would be "cocaine", was one of the most traumatic and alienating experiences of your entire life so far.
You could add, if the apparently-cocaine-scented individual of today appears at all interested in that traumatic experience from your own life, that during your own prior days as a full-time professional copy editor at "The Patriot Ledger" daily newspaper in downtown Quincy, Massachusetts (if true, and it definitely is an accurate factual recollection from my own life), a seemingly friendly female intern for that daily newspaper who identified herself as being a petite Anglo female college student studying journalism at either Northeastern University in Boston or Boston University in Boston, on her own initiative invited you yourself to attend a "party" with her that was being hosted by a cited male friend of hers inside his home in north Quincy --- a male friend of hers whom she felt very sure you would yourself enjoy meeting in person, she stated.
You could add to your account you volunteer to the cocaine-scented individual that when you in late 1985 or early 1986 attended that north Quincy event accompanied by the college student coworker named Nancy (last name withheld for the sake of propriety), you were shocked to learn that the bald reportedly "gay" Anglo male host had made "cocaine" his motif for the event, and that this gay male host was handing out cocaine to any and all guests, with yourself having been so thoroughly alienated by that "party", albeit in a civil and law-abiding and polite manner on your part, that you politely informed your "Patriot Ledger" daily newspaper female coworker seconds later inside the host's home that you could not endure any more of that party and would have to leave immediately, with Nancy Welch having stated that she herself insisted on remaining at that party site, with the two of you saying good-bye to each other at that time.
---You could politely point out to him that anyone who purchases cocaine from a drug dealer anywhere in Central Texas is thereby identifying himself as being a financier of the organized crime underworld of Central Texas, and that it is always preferable to NEVER be a financier of or participant in organized crime or crime, in your opinion.
---You could politely volunteer to him that individuals who consume the illicit drug cocaine are much more likely to get fired by their employer than are individuals who don't consume cocaine, with yourself politely adding that you will have to pursue some factual research to obtain a statistical estimate on what the increased risk of getting fired by one's employer is for anyone consuming cocaine.
---You could politely mention to him that you hope he is aware that anyone who ever consumes cocaine on any occasion is at increased risk of getting arrested by his local police department, such as the Austin Police Department in the case of anyone residing inside the city limits of this capital city of Texas, with that crime suspect then being charged with a felony crime in a court of law.
--You could politely ask him if he would like to play a word-association game in which the featured words would be "coke," "cocaine," "free-basing", "crack," "bad drug trip", "suicide," "self-destructive", "drug dealer", "fatal", "accelerated aging process", "snort", "emergency room", "arrest", "prison", "prison rape", and "death".
---You could politely volunteer to them (only if true, as it is in my case) that in the early 1990s, you yourself once resided alone for a brief multi-week period as a rent-paying official tenant at an apartment complex in east Austin where many of your next-door neighbors were reportedly or allegedly consuming the illicit drug crack cocaine, and that you personally hated the awful stench of that particular very injurious illicit drug emanating from inside those individuals' rental apartment units when you walked outdoors around the property of that complex.
As you offer that account, you could discreetly study the facial expression of the apparently cocaine-scented individual you are speaking with, to see whether your factual account from your own life has possibly triggered a look of sorrow or regret or sadness by himself. If so, you could then ask follow-up questions aimed at helping him to avoid consuming cocaine ever again.
---You could ask him if he supports the current laws that outlaw cocaine trafficking and cocaine consumption. If he answers "yes" to that, you could mention a good anti-illicit-drug non-profit group he might want to consider attending a meeting of here in town.
--You could ask him if he has ever had a friend of his who was addicted to any illicit drug, and if so, how did he himself attempt to help his friend?
---If you are also a mutual-consent personal friend of that individual, you can urge him to enroll in an affordable illicit-drug-addiction-treatment program that will help him to protect his medical health and save his own life as soon as possible. You could even offer to contribute financially toward your friend's noble cause of seeking to get cured of his own apparent addiction to cocaine.
---You could politely ask him if any of his current friends or relatives whom he keeps up with are persons he regards as being very honest and law-abiding and might be willing to meet with him during this very crucial period for him?
----You could ask him if he feels sure that all of the persons he "hangs out with" during his leisuretime these days are honest and law-abiding and good persons for him to associate with?