Common Side Effects Season 2 Set For 2027, Creators Tease Bigger Story At Annecy WIP Session

Adult Swim has confirmed that Common Side Effects Season 2 will be released in 2027, during a Work in Progress session at the 2026 Annecy Animation Film Festival. Co-creators Joe Bennett and Steve Hely pulled back the curtain on their much-anticipated sophomore season alongside supervising director Benjy Brooke and director Camille Bozec.

The first season was a high-octane fugitive-on-the-run story that hit the ground running and never slowed down. It follows a mycologist named Marshall Cuso, who encounters a mushroom capable of curing all injuries and illnesses and finds himself on the run from the government and Big Pharma. The first season ended with the mushroom being declared highly illegal, and Marshall barely escaping a raid on a farm growing his mushroom before heading to California, which, according to Hely, allows Season 2 to slow down and tell a story about people in hiding.

“It seemed to us that there might be a story here about people hiding out, trying to establish a little space and staying off the grid,” Steve Hely told Cartoon Brew ahead of the Annecy presentation. “It allows us to have the characters come to terms with what they’ve been dealing with, which we thought might seem stagnant or not as exciting, but it actually has its own tension.”

“We can sit with these characters a little bit longer and not feel like we had to rush things,” added Joe Bennett. “People are now familiar with Marshall and Frances, so you can kind of just be with them and have slower scenes and moments of levity. But we are still pushing our resources, like the number of locations, new characters. Everything is bigger, even if it also feels smaller.”

Indeed, while Season 1 was more of a road-trip story with Marshall on the run, Season 2 heads to Oregon, with Bennett teasing that a big part of the story will focus on a specific town. Here, Marshall will start digging into the mysterious “portal” that appears to those who take the mushroom, while Frances does some Erin Brockovich-style work helping people.

This meant the animation team, especially the background artists, had to do a lot of research to ensure the show captured the reality of its setting. Even if Common Side Effects is full of fantastical elements, little white creatures that appear in mushroom-induced hallucinations, characters with very big heads, and more, the aim is to make it look like the real world. This is most evident in the backgrounds of the animated series, which take an almost hyper-realistic approach.

This was always a tenet of Common Side Effects: the idea that it would be a fantastical story taking place in the real world. The diners, the towns, and the little motels we visit are meant to be as real as possible. “We have this incredible team of background people who give it this moody atmosphere and are accurate to the real thing,” Hely said. For Season 2, the research focused more on making this Oregon town feel real, alive, and full of history and people living their own lives. Though the presentation was light on plot details, the creators teased some of what audiences can expect from the upcoming season, including a villain hunting Marshall for his poor treatment of the mushroom, which the villain considers an almost religious object.

One piece of footage shown was a montage featuring numerous layouts and objects being placed on a table. Supervising director Benjy Brooke said this was not cheap and took a lot of time for the artists to make. Still, as inconvenient as it was, Brooke vowed, “Green Street Pictures will never use AI,” to thunderous applause from the Annecy audience. “F*** AI! Boycott AI,” Brooke continued.

The mushroom will, unsurprisingly, play a crucial role in the show’s second season. For this season, the team did extensive research not just into DEA agents and mycologists, but also with lawyers specializing in what would happen if a new psychedelic were introduced, and even archaeologists. This is because Common Side Effects will dive deeper into the mushroom’s history.

“There’s more of a lore that’s attached to the mushroom, and that’s a really fun part of the season,” Bennett said. But before you get too excited, the show is not going to do a long flashback episode explaining every single detail about the pseudo-magical properties of the mushroom and its history.

According to Steve Hely, producers Greg Daniels and Mike Judge have a guiding principle for lore and worldbuilding, likening it to turning over cards in a deck. Every time you turn a card over, it should suggest there’s more to unravel with the next one, and the next one, giving audiences something to keep their attention, while still leaving room for more.

“I think people are smart,” Bennett continued. “It just seems silly to hold the audience’s hand with everything, and I like giving the audience credit. They want to figure stuff out. We certainly do have a kind of map of what the mushroom is and all of that, but it doesn’t make sense to spell it out. What’s the fun in that?”

Part of what makes Common Side Effects unique visually is how cinematic the show looks, with Bennett and Hely taking more inspiration from live-action cinema than animation to give the show a grounded, realistic style. For the upcoming season, the team looked at conspiracy thrillers like Michael Clayton, JFK, The Insider, movies about trials and hearings, and also Indiana Jones and National Treasure. Sure, conspiracy thrillers make sense, as they drive much of the narrative. The trial and hearing movies also make sense, considering the first season ended with Reutical Pharmaceuticals, Inc. getting its hands on the mushroom and presumably attempting to release it to the masses somehow. But what about Indiana Jones?

“That’s more for the idea of an adventure with a good balance of action and lighthearted dynamics,” Bennett explained. “We want a story where you start following something, but it ends up taking you to these strange places, and then you’re too far in to get out.”

With Season 2 set for release in 2027, what’s next? According to Steve Hely, this is but a small part of their larger plan.

“We think in terms of Season 10, not necessarily season by season,” Hely said. “This is the beginning of Copano and Harrington’s arc, which will take us down to some other channel, and we’ll then come back around and weave through the storylines. But we’re setting little points for the future all the time.”