Medical Conditions (Australia)

Scroll down the page to find the information that pertains to your declared medical condition/s. 

Cardiac Causes

Fatalities from cardiac events while diving and snorkelling have become increasingly common as older people take up diving, and younger divers age. Diving (and snorkelling) can add substantial additional cardiac stressors in the form of exertion, immersion, sometimes heavy and restrictive equipment, increased breathing effort, salt water aspiration and anxiety, among others. This can be a recipe for causing a cardiac event in someone with pre-existing cardiovascular disease, whether diagnosed or not. It is important that any diver with a known cardiac problem discusses their personal situation with a doctor who is aware of the cardiac stressors involved with diving. DAN World recommends that all divers have regular health checks. For males aged 45 and females aged 55 this should include a cardiovascular assessment. 


The major concern with diving and diabetes is the potential for suffering severe hypoglycaemia (low blood sugar levels), causing a reduced level of consciousness or mobility in the water. Factors such as exercise, stress and a variety of others can lower blood sugar levels substantially and, unless the diver is well-controlled and well-monitored, an accident could result. In addition, the usual cues of hypoglycaemia may not be obvious in the underwater environment. It is recommended that all diabetic divers and their treating doctors familiarize themselves with the current Undersea and Hyperbaric Medical Society Guidelines. 


Hypertension (High Blood Pressure), whether treated with medication or not, may be associated with an increased risk of cardiac problems and stroke (cerebrovascular disease).  In addition, certain medications used in the management of hypertension may have undesirable consequences for the diver (such as beta-blockers limiting physical exertion or increasing the potential for pulmonary oedema, or diuretics leading to dehydration). This can sometimes lead to serious problems. Therefore we advise that you discuss the management of your hypertension and the choice of medication with your treating doctor.

Patent Foramen Ovale (PFO)

Divers with a PFO appear to be at a (sometimes) substantially greater risk of decompression illness (DCI) as venous bubbles can be shunted into the arterial circulation though the PFO. Diving conservatively to minimize bubbles should reduce the likelihood of a problem. Staying well away from dive computer and table limits, ascending slowly, doing safety stops, increasing surface interval times and minimizing the number of repetitive dives should reduce bubble formation.

Pre-Existing Injury

Certain injuries can reduce the mobility of a diver and may increase the potential for an accident while diving. In addition, pre-existing injury is often associated with scar tissue and reduced circulation and so may increase the likelihood of decompression illness. Divers with pre-existing injuries are advised to dive within their capabilities and to be more conservative in their diving profiles to reduce the likelihood of DCI.

Previous Decompression Illness (DCI)

If you have had a previous episode of decompression illness (DCI) or suspected DCI, it is possible in most cases to return to diving once cleared to do so by a diving physician. However, it is usually advisable to dive more conservatively as there may be an increased risk of a future DCI episode. 

DAN makes available to Members a valuable information booklet called Enfermedad disbárica*, authored by DAN World Founder, and dive safety author John Lippmann. The booklet provides useful recommendations to reduce the risk of DCI, and include:

  1. Restricting depths to less than about 30 metres.
  2. Avoiding mandatory decompression.
  3. Using conservative dive times (e.g. setting dive computer to a more conservative setting can help).
  4. Ascending slowly and doing a safety stop (or stops).
  5. Limiting the number of daily dives.
  6. Extending surface intervals (a minimum of 2 hours, where possible).
  7. Using nitrox (with an air setting on the dive computer).

You can find additional information in the booklet pertaining to signs & symptoms, risk factors for DCI, prevention of DCI, and diving with a Patent Foramen Ovale (PFO).