1. Symptoms do not reliably distinguish decompression disorders

Pressure changes and breathing-gas exposure during diving can lead to decompression sickness (DCS) or arterial gas embolism (AGE), among other problems. Rapid ascents, dives outside the plan, and repetitive dives can affect risk, but a controlled ascent does not rule out illness. Rash, joint or muscle pain, tingling, weakness, changes in balance, vision or speech, breathlessness, chest pain, or altered consciousness after diving warrant assessment.

Symptoms can begin after surfacing, be delayed, or improve and then return. Do not diagnose DCS versus AGE or grade severity from symptoms alone. Record depth, time, ascent profile, breathing gas, and symptom onset to help a diving-medicine professional evaluate the event.

2. Get emergency care and provide oxygen first aid when appropriate

Stop diving and bring the diver safely out of the water. Contact emergency medical services and DAN or a diving-medicine specialist promptly. If trained and equipped to do so safely, provide high-concentration oxygen as first aid. Improvement with oxygen does not cancel the need for evaluation or evacuation; DAN advises assessment even if symptoms resolve temporarily.

Monitor breathing and responsiveness, and use CPR or an AED within your training if needed. Do not force fluids on someone who is not alert and able to swallow. Do not self-treat with pain medicine or another dive. Do not attempt in-water recompression as a traveler’s first-aid measure; drowning, hypothermia, and other hazards make this inappropriate. Follow emergency services and diving-medicine experts on stabilization and transport.

3. Recompression is determined by specialists after assessment

Recompression in a chamber is used for many cases of decompression illness, but the same chamber pressure, oxygen schedule, and treatment duration do not automatically apply to every post-dive symptom. Emergency evaluation and stabilization might be needed first, and transport to a chamber should be coordinated with local clinicians and diving-medicine advice. Whether oxygen or a particular treatment table is appropriate is a clinical decision.

Travelers should not apply a U.S. Navy treatment table, a fixed pressure, or an oxygen percentage on their own, or delay care while watching symptoms. Share dive profiles, breathing gas, equipment, symptom changes, and first aid already given with the rescue team. Before a remote dive trip, identify emergency contacts and the nearest emergency and diving-medicine facilities.

4. Post-dive flight intervals are minimum guidance, not a guarantee

DAN’s recreational flying-after-diving guidance applies to divers without DCS symptoms after dives within no-decompression limits. It recommends a minimum surface interval of 12 hours after a single no-decompression dive and 18 hours after multiple dives in one day or dives on multiple days. For dives requiring decompression stops, evidence is limited; DAN says a surface interval substantially longer than 18 hours appears prudent. These intervals are intended to reduce risk and do not guarantee that DCS will be avoided.

Do not apply this simplified guidance automatically to technical diving, decompression dives, a diver with symptoms, or flights with different cabin altitudes. Follow dive-computer or training-agency guidance and consult a diving-medicine professional. If symptoms suggest DCS, do not fly; seek urgent medical advice.

Sources and references: Divers Alert Network: Decompression Illness / DAN: Flying After Diving