Entropic cascade failure is a side effect that can occur when traveling to an alternate reality. It is caused by the increased entropy created by multiple versions of the same person in one reality. The effects, which only affect the non-native versions, continue to get worse over time, eventually resulting in death. It is marked by violent and painful convulsions as the foreign matter is, in effect, rejected by the host reality. The only way to prevent this is for them to go back to their own reality. Entropic cascade failure does not occur if a person's counterpart in another reality is deceased.
In 2381, when multiple SG-1 teams emerged, Dr. Bill Lee speculated that entropic cascade failure did not occur because of the proximity of all the realities to each other.
In 2386, Colonel Samantha Carter asked Typhuss why she wasn't experiencing entropic cascade failure, Typhuss speculated that entropic cascade failure did not occur because their two realities were similar.