The Mystical Palm Technique (掌仙術, Shōsen Jutsu) is a medical ninjutsu technique that sends chakra from the hands into a wounded area to accelerate the body's natural healing abilities. Among healing jutsu, this technique is the most basic and the rest are derived from this one. This technique is normally used to treat external injuries, although it can also be used for internal injuries. Users must be careful to adapt the chakra to the level of the injury and only use as much as is needed. If too much chakra is sent into the body, this can disrupt the body's circulation, putting it into a comatose state[1][2]. For this reason, few medical-nin can use this technique because of the chakra control required to safely use it.
Aspiring medical-nin to learn how to control their chakra efficiently by practicing on inanimate objects or living beings. For example, when Sakura Haruno is learning how to use it, she practices on a fish and her natural talent with chakra control allowed her to grasp this technique in only three months, prompting Tsunade to say that this proficiency is exceptionally rare[3]. However, when Sarada Uchiha practiced on a fish, she sent too much chakra and caused it to eventually burn up[4]. When a ninja masters this technique, they're ready to act as field medic-nin. In the anime, it's stated that the different hidden villages have all developed their own applications for this technique that are unknown to other villages; in Kirigakure's case, its medic-nin can use it as a remedy for seasickness[5].
This technique can be enhanced to apply it to other fields or expand it's range. For example, Sakura Haruno is able to heal herself while fighting or being impaled, which is known as the "pinnacle of external injury treatment"[6] and Kabuto Yakushi has been shown using this jutsu from a short distance away, without directly touching the person he's healing[7]. Tsunade is the only person known to be able to heal the effects of a Tsukuyomi[8]