Almost all cases of decompression illness require treatment in a recompression chamber, during which the diver is put back under pressure to help the body absorb bubbles in the tissues. This treatment usually takes several hours, requires the use of pure oxygen, and often drug therapies. Don't allow a diver suspected of having decompression illness to go back underwater. Attempts to treat a diver underwater typically end with worsened symptom and disastrous results, and only delay getting to proper treatment.

Although decompression sickness is a serious condition, both painful and potentially life threatening, it is avoided by properly following the established safe time and depth limits of dive tables and dive computers. Lung over expansion injuries are also serious, painful and potentially life-threatening, but avoided by breathing continuously and never holding your breath. Additionally important in preventing decompression illness (both DCS and lung over expansion injuries) is a slow, safe ascent rate with a stop for safety at 5 metres/15 feet. You'll learn more about this stop in Section Five.