Common Side Effects

Common Side Effects is an American adult animated television series created by Joseph Bennett and Steve Hely for Cartoon Network's Adult Swim block with availability on Max.

The pilot episode premiered privately at the Annecy International Animation Film Festival in June 2024, and publicly a month later at Adult Swim's San Diego Comic-Con panel in July 2024. The series premiered on Adult Swim on February 2, 2025, to critical acclaim. The series has an encore broadcast on the network's Toonami programming block that began on March 2, 2025. On March 28, 2025, it was announced the series was renewed for a second season.

Two high school friends, Marshall and Frances, reconnect after Marshall discovers the Blue Angel Mushroom, a mushroom with healing effects that appears to cure all illnesses. In the process, they also uncover a conspiracy involving Reutical Pharmaceuticals, Inc., one of the largest pharmaceutical companies, and the government, to suppress all knowledge of said mushroom.

• Marshall Cuso (voiced by Dave King) is the knowledgeable, cautious protagonist of the series and was friends with Frances in high school. He is an accomplished expert in fungi who has done charity work in foreign countries and is sly in run-ins with the DEA.
• Frances Applewhite (voiced by Emily Pendergast) is Rick's executive assistant and Marshall's high school lab mate and friend. Though initially hesitant about the effects of the Blue Angel, she eventually sees the monetary value in the mushrooms and is motivated to try and get them to Rick to take care of her mother, who was recently diagnosed with dementia.
• Agents Copano (voiced by Joseph Lee Anderson) and Harrington (voiced by Martha Kelly) are nonchalant best friends who work for the Drug Enforcement Administration. Kelly describes Harrington as "goofy but is very pragmatic about [her] job.", while Anderson describes Copano as someone who is "big on conspiracy theories" and who likes to "connect dots when they probably should not be connected."
• Rick Kruger (voiced by Mike Judge) is the incompetent chief executive officer of Reutical, who constantly bothers Frances to do mundane tasks for him, such as booking reservations and changing the TV channel. He also enjoys farming simulator video games, often playing in improper settings such as work and formal events.

• Nick (voiced by Ben Feldman) is Frances' lackadaisical, often oblivious boyfriend who loves VR gaming. Feldman also provides additional voices.
• Jonas Backstein (voiced by Danny Huston) is a powerful Swiss financier and board member of Reutical with heavy insider ties to the federal government who is focused on destroying Marshall and the mushrooms.
• Cecily (voiced by Sydney Poitier) is a Deputy National Security Director with influence over the DEA who secretly conspires with Jonas and Reutical.
• Hildy (voiced by Sue Rose) is Marshall's idiosyncratic, mycologist mentor who seeks to possess the Blue Angel for her own ends.
• Sonia Applewhite (voiced by Lin Shaye) is Frances' mother who has been diagnosed with dementia, and is Frances' main motivation for acquiring the Blue Angel mushroom.
• Amelia (voiced by Shannon Woodward) is the laid-back mycologist hired by the DEA to gather information on the Blue Angel, also acting as a single mother and caretaker to her ill son, Wyatt. Woodward also provides additional voices.
• Kiki (voiced by Christine Ko) is a researcher at Reutical. Young and knowledgeable on medicine and the pharmaceutical system, she acts as the devil's advocate for the company, disputing the arguments brought up by people such as Marshall.
• Zane (voiced by Alan Resnick) is Marshall's veterinarian half-brother specializing in marine animals. He enjoys taking psychedelic drugs and illegally imports rare tropical animals.
• Kenji is Copano and Harrington's boss at the DEA.
• Jimmer Jarvis (voiced by Mike Judge) is the Sheriff of Averesboro, North Carolina who becomes Marshall's next-door neighbor and ally.
• Rusty is Jimmer’s redneck nephew who spends most of his time shooting guns or riding his BMX bike.

• Shalita Grant as Female DEA Agent / Susan / Kelly
• Bob Stephenson as Connor / Samurai
• Timothy Simons as DEA Dispatcher / Lawyer / Test Subject 3
• Andy Daly as Mysterious Passenger / Christopher
• Nicolas Cantu as Tommy

Common Side Effects co-creators Joseph Bennett and Steve Hely were brought together and began development of the series in 2019 under production studio Bandera Entertainment founded by Mike Judge and Greg Daniels. Bennett and Hely sought to combine the crime thriller genre with comedy, inspired by the films of the Coen brothers, such as Burn After Reading. Inspiration for the story came from the co-creators' interest in medicine and the work of mycologist Paul Stamets, ethnobotanists Richard Evan Schultes, Terence McKenna and Wade Davis, and the chemist Albert Hofmann. The character Marshall was in part inspired by Stamets and "The Orchid Thief" John Laroche as he was portrayed in the film Adaptation. Another inspiration was the story of R. Gordon Wasson publishing an article about Psilocybin mushroooms and María Sabina in Life magazine and the dramatic consequences for the life of Maria Sabina once the article was published.

Animation for the series was produced by Green Street Pictures employing an international team of artists, including some working remotely from France, Portugal, Spain, and Mexico. Many of these artists worked on Scavengers Reign, a 2023 series also produced by Green Street and co-created by Bennett. Animation was produced in conjunction with Le Cube, a partner studio in Argentina.

The series was first announced in June 2023, at the Annecy International Animation Film Festival. The pilot episode premiered privately at the festival event the following year.

The review aggregator website Rotten Tomatoes reported a 100% approval rating with an average rating of 8.7/10, based on 25 critic reviews. The website's critics consensus reads, "An addictive mix of expressive animation, heady concepts, and an offbeat sense of humor, Common Side Effects is a must-have prescription." Metacritic, which uses a weighted average, assigned a score of 80 out of 100 based on 6 critics, indicating "Generally Favorable" reviews.

• Official website
• Common Side Effects at IMDb 
• Common Side Effects at Metacritic
• Common Side Effects at Rotten Tomatoes