The Island appears to have healing properties that cures inhabitants of defects, disabilities and diseases. Most notably, Locke (paralysis) and Rose (cancer) both believe the Island can heal afflictions.
The Healed
- On Day 1, in the Pilot, Jack is wounded in the side. Kate sews up the wound. In later episodes, this wound never bothers Jack.
- In Walkabout, we learn that Locke was paralyzed and started to walk again after crashing on the Island.
- In Deus Ex Machina, the Island appears to take away Locke’s ability to walk. Locke believes the Island is punishing him and demanding him to complete a task. After he finds the plane filled with heroin and Boone is fatally wounded, he no longer has trouble walking.
- In The Whole Truth, we learn Jin is sterile and unable to have children. However, we also learn that Sun is pregnant. Sun claims to have slept with no other man than Jin. If this is true, then it would appear to indicate that Jin has been cured of his sterility by the Island.
- Day 44, Sawyer is shot on the boat (not on the Island). On Day 48, Jack begins treating the wound. Sawyer, at this point, is unconscious. Sawyer heals rapidly and the following day feels well enough to walk around with Kate. By Day 56, Sawyer acquires the guns in The Long Con. By Day 63, in Dave, Sawyer appears fully healed and capable of looting the Supply Drop and brawling with Hurley.
- Day 44, Charlie is wounded by a booby-trap set by Rousseau. The wound is cauterized by Sayid with gunpowder. In later episodes, we see no evidence of this wound.
- In All the Best Cowboys Have Daddy Issues Charlie is resuccitated by Jack after being hung by Ethan. This may be considered 'Normal Healing,' yet Charlie was brought back by CPR from a critical or perhaps dead state. The writers purpously gave the impression that Jack had entered into the realm of irrationality with his attempts to save Charlie.
- In S.O.S., we learn that Rose is dying of cancer and has very little time left to live. Since crashing on the Island, she’s noticed a difference in herself and believes she has been cured.
The UnHealed
While the above instances appear to indicate healing properties, there are other examples where people were NOT healed.
- The Pilot, presumably killed by The Security System.
- Edward Mars, the US Marshall escorting Kate back to the United States suffers a severe injury to and has a piece of fuselage sticking out of his abdomen. Shot by Sawyer and didn’t die. Killed by Jack as an act of mercy.
- Donald, a tailender died from infection of leg injury sustained from the plane crash on day 5.
- Three additional unnamed Tailenders died as a result of injuries received in the crash.
- Joanna, caught in a riptide and drowns in the ocean off the coast of the Island.
- Shannon had asthma.
- Ethan Rom, killed by Charlie.
- Nathan, killed by Goodwin.
- Goodwin, killed by Ana-Lucia.
- Boone suffers a fatal injury when the plane filled with heroin falls from its perch and crashes to the ground. Locke carries him to The Caves where he ultimately dies.
- Shannon, killed by Ana-Lucia.
Healed, but seemingly at a normal pace
- Henry Gale is wounded by Rousseau in the shoulder on Day 57. By Day 65, in S.O.S., Henry’s wound appears better, but not at the same incredible rate that Sawyer was healed from the gunshot.
- Locke's facial scar over his right eye.
- Aaron's (presumably) routine childhood rash.
Theories
- As proposed by Isaac of Uluru in S.O.S., there are certain places that have an abundance of Life Force Energy that can be used to heal injuries. Isaac told Rose that his location in Australia was not “her place” for healing. Presumably, The Island is “her place.”
- The Island is a shared hallucination, so the injury and healings are imagined. Sawyer was never shot. Locke is still paralyzed. Rose still has cancer.
- The Marshall would have lived through his injuries if not shot by Sawyer and then killed by Jack.
- There are no healing properties at all and the characters who believe so are misinterpreting events and/or feelings.