A lifelong comedy writer, Donick Cary knows full well that some entertainers radiate a sort of effortless interestingness. They’re good off the cuff, they have an unending backlog of amusing stories, and they share these anecdotes with colorful, spellbinding delivery. “My experience on Letterman was always that if we could find funny people and follow them around, we’d get something good,” Cary tells the Guardian by phone from his home quarantine. “Easier on the writers, too.”

That’s the presumption around which the new documentary Have a Good Trip: Adventures in Psychedelics has been built. The film compiles a selection of candid, revealing interviews recorded over the last 11 years with a jam-packed roster of talent, all of them getting real about their dalliances with mind-altering substances. Their recollections run the gamut from the transcendent to the euphoric to the silly to the nightmarish, forming a surprisingly sober-minded portrait of drugs as a subjective force neither good nor bad, depending only on how a person uses it.

“I’ve always loved documentaries, real stories about real people,” Cary says. “I was at the Nantucket film festival about 11 years ago, and Ben Stiller’s on the board. Fisher Stevens was also there to launch The Cove, and we all ended up in a conversation about psychedelics and people’s experiences, which turned out to be so entertaining. The Aristocrats had come out a few years before, and I realized how much I liked this vibe of an extended dinner party, with everyone sharing a story.”

So began an off-and-on project that would stretch out over the next decade, as Cary undertook the work of securing interview times with a lineup of subjects that he estimates as somewhere between 75 and 100. The array of familiar faces making the cut ranges from standup and sketch’s usual suspects (Nick Kroll, David Cross, Sarah Silverman) to musical luminaries (A$AP Rocky, Sting) and late legends with an unexpectedly poignant presence (Carrie Fisher and Anthony Bourdain appear posthumously). “We were at the mercy of 100 celebrities’ schedules,” Cary says. “Someone like Sting would be available, but he’s got a concert tour and he’s doing a stage show in London and all this other stuff. He was great, though. We just had to wait nine months.”

Restricting himself to an 89-minute run time meant that he had to ditch the lion’s share of footage on the cutting room floor, a pain that years of “killing your babies” in writers’ rooms had prepared him for. Nevertheless, that left him with some great tidbits of his own. He says he’s got enough material for three or four more features, which might afford him a place for the clips with Whitney Cummings, Patton Oswalt, Bootsy Collins and Ed Ruscha, a cursory sampling of his unused favorites. Some A-listers, like Dave Grohl and Paul McCartney, just weren’t gettable. In other cases, Cary got the goods, but had trouble clinching permissions.

“We did sit down with Ozzy [Osbourne], and ended up not using it,” Cary recalls. “He didn’t feel comfortable after he’d told his story. He was like, ‘I don’t think I want to be in a drug movie.’ Which was fine! We respect that from anyone, but man, he’s got some stories … I got on the phone with Susan Sarandon, and we talked for an hour-plus on two or three occasions. But we couldn’t get her to commit to doing it or not. She had such wonderful things to say – she knew Timothy Leary, you know. But I guess I couldn’t get her to feel fully comfortable about the project. Still, these are people we were ridiculously lucky to have a little time with.”

Once he’d amassed a satisfactory library of interviews to select from, Cary had to turn himself into a proper film-maker, deciding what he wanted his work to say and look like. An afternoon spent watching the Coen brothers’ The Ballad of Buster Scruggs inspired him to adopt an episodic structure, taking the yarns one by one instead of cross-cutting between them. He decided to liven things up by accompanying some segments with animated illustrations of the hijinks being related, and others with low-budget live-action re-enactments. To break up the action, he inserted a recurring faux after-school special in which four “teens” played by actors visibly in their 30s bug out after getting dosed. Cary plays it all like a joke, but he buried a real message about intelligent, responsible usage in his shtick.

“The takeaway should not be that we’re advocating this for everyone, or that absolutely everyone should do drugs,” he says. “No one should get peer-pressured into taking it, because if you start with fear and trepidation, you’re much more likely to have a bad time.”

In his own soundbites as well as the ones he selected and arranged for the film, Cary urges care and preparation. Hunter S Thompson, William Burroughs, Michael Pollan, and Carlos Castaneda fill out his recommended reading list for squares curious about the ins and outs of consciousness expansion. He wants to demystify psychotropics, which could stand to benefit more people than previously assumed. “What’s been great in the last two or three years has been seeing a destigmatization and a more rational conversation about using psychedelics for therapy, or in therapeutic settings instead of party settings,” he says. “One of the big things we’re up against as humans is empathizing, being able to think from another person’s point of view. Psychedelics can help a person get out of their own box, and think their way into someone else’s.”

He’s more grounded than most of acid’s tie-dyed advocates, yet not without an optimism about all it can do. “These remind you that we’re supposed to love each other,” he says, the closest he comes to an impression of a hippy. But he’s dubious of microdosing, which he believes can work but overall finds “a bit faddish”. Altogether, he comes off as a man who knows his stuff, which raises the obvious question: what hands-on field research has he conducted to become an authority on the matter? He lets out the sheepish chuckle of someone who’s seen it all, or at least seen plenty, and knows better than to give away his best stuff.

“I don’t mean to be a politician about it – I’ve certainly had some experiences – but I’m careful because I’m raising kids,” Cary says. “One nice thing about this all taking 11 years has been that my kids have aged through a lot of different times in their lives, and that makes me think about what I want them to see in this movie and take away from it. I want it to be balanced and rational for that kind of viewer.

“Psychedelics are taken in a lot of recreational situations, but it’s not a recreational drug, it’s pretty powerful. It can be used for incredible things, but do the work and exercise caution.”

• Have a Good Trip: Adventures in Psychedelics is now available on Netflix