Elixir Injection

An Elixir Injection (エリキシル 注射) is a powerful concentrated drug of yellow blood cells that induces proliferation to increase a parasite’s aptitude results.

Overview
The drug was designed as a last resort for children, who were still undergoing their parasite development in the Garden, and who failed to meet expectations. If their capacity and aptitude results failed to thrive or showed incompetence, they were at risk of being removed from the Garden and pruned (eliminated and thrown away). It was revealed in Episode 22 that Dr. FRANXX had stored these children in a cryogenic room, as he opposed APE’s method of disposing weak children.

While the drug would drastically increase one’s aptitude results, it had a success rate of 15% (1% in the manga). Because of this, many children were reluctant to receive the injection out of fear of succumbing to its effects. Mitsuru received the injection when he was 9-years-old when he was told he couldn’t stay in the Garden due to his low aptitude results. According to Ichigo, he was the only one to have received it and came back alive.

While the drug can increase a one's aptitude tremendously, it also causes the physical and mental health of the receiver to significantly weaken, making the individual grow increasingly sick and mentally unstable.

Trivia

 * Elixir is a clear, sweet-flavored liquid used for medical purposes, to be taken orally and intended to cure one's illness.
 * In addition, Elixir has several meanings.
 * (1): a substance held capable of changing base metals into gold
 * (2): a substance held capable of prolonging life indefinitely
 * (3): a medicinal concoction
 * (4): a sweetened liquid usually containing alcohol that is used in medication either for its medicinal ingredients or as a flavoring
 * Elixir is also the main mechanic of the game Clash Royale, and a currency in the game Clash of Clans