This page is move protected The subject of this article is involved with the Once Upon a Time The subject of this article is an item The subject of this article is involved with Victorian England The subject of this article is involved with the Land of Untold Stories The subject of this article is involved with the Land Without Magic The subject of this article is magical or capable of using magic The subject of this article is featured in Season Five of Once Upon a Time The subject of this article is featured in Season Six of Once Upon a Time

A serum I created, designed to separate the good from the evil in someone.

Dr. Jekyll src

Dr. Jekyll's Serums are liquids featured on ABC's Once Upon a Time. They first appear in the twenty-second episode of the fifth season.

Dr. Jekyll's Serums are based on the item of the same name from Strange Case of Dr Jekyll and Mr Hyde.


Before First Curse
In Victorian England, the serum is the dream project of Dr. Jekyll. By finishing the serum, he hopes to impress Dr. Lydgate and be accepted into the science academy. He explains to Dr. Lydgate about the properties of the serum, which will give a man control over his darker tendencies. Unfortunately, Lydgate turns him down, describing his work as dangerous. A disappointed Jekyll is later visited by Rumplestiltskin, who has heard of the serum and hopes to forget his love for his maid, Belle, by ingesting it. Rumplestiltskin uses Jekyll as a test subject by using magic to finish the serum and persuades him that the serum is the secret to getting what he wants: Mary, the daughter of Dr. Lydgate and Jekyll's close friend for whom Jekyll holds unreciprocated feelings. Convinced, Jekyll downs the serum and is transformed into a man who Rumplestiltskin dubs Mr. Hyde. Hyde is able to convince Lydgate to let Jekyll join the academy, and when the serum wears off, Jekyll awakens to find the pendant as proof of his acceptance. Rumplestiltskin points out that he still does not have Mary's affections and suggests he try again, so Jekyll drinks more of the serum. Hyde meets Mary in a street and tells her of the doctor's affections, but Mary instead falls for Hyde. This time, when the serum wears off, Jekyll awakens in Mary's bedchamber, after Mary and Hyde spent the night together. Angry and heartbroken at Hyde's betrayal and Mary's refusal to love him, Jekyll accidentally pushes Mary out her window. To avoid being caught for this crime, he drinks the serum once more to frame Mr. Hyde. Hyde flees to the laboratory, where he insists to Rumplestiltskin that he would never hurt Mary since he loved her. Rumplestiltskin becomes angry that the serum could not wipe out Hyde's capacity for love and forces Hyde, and therefore Jekyll, into a portal to the Land of Untold Stories. ("Strange Case")

After Third Curse

Still in the Land of Untold Stories, Mr. Hyde enlists an orderly, Poole, to keep watch on Dr. Jekyll to ensure he doesn’t try to flee. Plotting to be free of his other half, Jekyll begins growing a purple flower in the courtyard, which is the final ingredient in a red serum meant to separate himself and Hyde into separate bodies. When a group of heroes becomes imprisoned by Hyde, Jekyll agrees to fix their wand that they need for returning home if they take him with them. After Jekyll has repaired the wand, Poole catches him and makes him ingest the blue serum to wake up Hyde. ("Only You")

Once Hyde takes away the wand and becomes dormant, Jekyll frees the prisoners and leads them to his old house to complete the red serum. Before Jekyll can drink it, Poole bursts in, once again making him down the blue serum to force out Hyde. After the heroes flee, Hyde ingests the red serum to separate himself from Jekyll. He then tries to strangle Jekyll, who he deems pathetic and weak, but the heroes return to stop him and save Jekyll. Prior to escaping into the city, Jekyll grabs what is left of the red serum. When a portal opens up from the Land Without Magic, Jekyll and the heroes jump in to get away from Hyde. ("An Untold Story")

The night before returning to Storybrooke, Jekyll gives the red serum to the heroes, as thanks for saving him. Snow notices Regina’s continued struggle with her darker instincts, and urges her to take the serum and kill the Evil Queen inside her. After injecting herself with the serum, Regina’s evil personality splits into a separate body from hers. While the Queen taunts Regina for her inability to kill her because she needs her, Regina musters up the strength to rip out the Queen’s heart and crush it. ("An Untold Story")

After the discovery that the Evil Queen is still alive, Jekyll begins working on another serum that could kill both the Queen and Hyde. However, he lacks the necessary laboratory tools to accomplish this, so Regina and Snow bring him to Dr. Whale's garage, where the two mad scientists begin working together. ("The Other Shoe")

Jekyll is continuing work on this serum when he receives Mary's necklace, which he deduces was sent by Hyde, who the Queen broke out of the mental ward. Emma, David, Regina, Leroy, and Doc join him in his new laboratory to protect him from Hyde, but Jekyll realizes that he needs Mr. Gold's help to finish the serum. While Emma and David hunt for Hyde and the Evil Queen, Regina goes to Mr. Gold, who agrees to help. While Regina is gone, Hyde and the Queen show up and knock the dwarves unconscious before smashing the serum and laboratory. Although Jekyll believes he has safely kept a small portion of the serum in his coat, Hyde is aware of its presence and switches it out with a fake. When Regina asks Mr. Gold to use his magic on this serum so that they can use it on the Evil Queen and Hyde, Mr. Gold rips out Jekyll's heart and explains that he has made a deal with the Evil Queen, and thus, will not use the serum on her. To save Jekyll, Regina agrees to pour the serum on the Dark One Dagger for Mr. Gold to use on Hyde. However, when Mr. Gold stabs Hyde with the serum, it has no effect due to the switch. Hyde takes the dagger out of his chest and then pulls out the actual serum vial from his jacket, which he destroys by throwing it onto a rock. ("Strange Case")


  • The original version of the serum was used to turn someone into their evil self. The latter can take the appearance of the person it is applied to, or it can take an entirely different appearance, depending on how they see their inner darkness. When they transform neither side has memory of what the other does ("An Untold Story")
  • An improved version of the serum was developed by adding a purple flower extract to the original substance, and it separates the personification of inner darkness from their body instead of transforming them. ("An Untold Story")
  • The original and evil selves have the same memories up to the point that they were first split.
  • In both cases, the evil self receives a body with extraordinary physical abilities. ("Only You")
    • Mr. Hyde was much stronger than a normal human and appears to be invulnerable to most forms of magic. ("An Untold Story")
    • The serum appears to manifest the dark personality with physical abilities respective to the original person's possible views about their dark selves. ("An Untold Story")
    • The serum counterparts are still linked to their original selves, and can only be killed if their original selves die. As such, the Evil Queen is able to stay alive even after having her heart crushed. ("An Untold Story", "Strange Case")
  • Serum counterparts are able to regrow their heart after it has been crushed. ("An Untold Story", "Page 23")


Community content is available under CC-BY-SA unless otherwise noted.