Common Side Effects episode 5 ending explained: Are Marshall and Frances able to regrow the mushroom?

Common Side Effects episode 5, titled Star-Tel-Lite, premiered on Adult Swim on February 23, 2025. Being the midpoint of the series, the episode focuses on Marshall and Frances as they navigate after the events that took place last episode. As they keep running out of mushrooms to grow, they finally do one Hail Mary, which might just change everything for them.

Warning: Spoilers for Common Side Effects episode 5 to follow. Reader's discretion is advised.

In Common Side Effects episode 5, Marshall and Frances are finally able to grow the mushrooms again. The way it comes about, however, leaves many moral questions, which does seem to confuse Marshall about how to go forward. It all culminates in a final few moments, which see Marshall get arrested by the police.

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How do the mushrooms regrow in Common Side Effects episode 5?

A still from Common Side Effects episode 5 (Image via Warner Bros. Entertainment)

In Common Side Effects episode 5, Marshall reveals to Frances that he has constantly tried to regrow the mushroom, but he has had no success in doing so. With Marshall only having one last strand of mushroom left with him, as he used the other to cure Jarvis' nephew Tommy of a lung disease that was threatening him, Frances recommended one last idea.

Seeing as Marshall found the blue mushroom just growing on the ground, Frances recommended he do the same rather than try and grow it in a lab. She then let Marshall's tortoise pick a perfect spot to drop the mushroom in, as he was there in Peru as well during the discovery.

After the tortoise picks a spot, Marshall and Frances drop the mushroom there and walk back to the cabin, and the tortoise then poops on it as well before leaving. The next morning, when Frances and Marshall wake up, they discover that there are multiple strains of the mushroom that have grown and are sprouting from the ground.

However, Marshall begins to have a panic attack about it as the morality of holding so much power begins to catch up to him. But Frances calms him down and recommends that they should try the mushrooms out just to celebrate.

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Cops get sent after Marshall

Rick talking to Frances (Image via Warner Bros. Entertainment)

Common Side Effects episode 5 then ends on a big dramatic note. When giving Tommy the mushroom, Frances decides to secretly record the event and sends it to Rick. As Rick sees that Tommy heals up miraculously, he begins to have a bit of hope as his job at Reutical is already at risk due to poor earnings reports. Rick then takes the video to Jonas in the hopes of saving his job.

However, Jonas tells Rick to stop believing in videos, as they can easily be faked nowadays, and that he needs solid, hard proof. He then stations Rick somewhere else, effectively changing his position at the company. However, Jonas does believe Rick and immediately calls up Cecily, asking her to take care of this situation at hand.

Since Marshall is in North Carolina, Cecily is able to send cops after Marshall.

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Marshall gets arrested

Common Side Effects episode 5 then ends with Marshall getting arrested by the cops. After trying out the mushroom, Marshall and Frances realize the nightmares they saw during their trip and get a little spooked by it. This leads to Frances finally being ready to admit why she sought out Marshall in the first place and exactly what her plan was to do with the mushrooms, but police arrive on the spot.

Marshall is then arrested by cops for committing arson in New York, and just as he is being taken to the cop car, he tells Frances to pack everything up and leave. However, Frances tells him that she has something to say to him, and Common Side Effects episode 5 ends with the two sharing a kiss.

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Copano and Harrington continue to suspect whats up

Copano and Harrington in the show (Image via Warner Bros. Entertainment)

Copano and Harrington then end up in North Carolina as well in Common Side Effects episode 5 after following Frances. There they find Marshall and her getting out of Jarvis' house, and they decide to further spy on them. Disguised as a satellite company called Star-Tel-Lite, they tell Jarvis' nephew Rusty that they have a special satellite deal for him.

However, Jarvis doesn't buy that excuse and tells them to walk away. He then warns Frances and Marshall of government people spying on them, and Marshall confronts them. He just tells them to wait one more day before doing anything, and the two agree.

They then finally believe that maybe Marshall and Frances might not be up to anything.

Common Side Effects episode 5 should be available for streaming on Max from tomorrow.

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