High Altitude / Acute Mountain Sickness

Acute Mountain Sickness

Acute Mountain Sickness (AMS) is common among travellers visiting destinations 2400 metres above sea level or higher. Around 50% of these travellers are affected by AMS.

Why? The higher the altitude, the less oxygen there is in the air.  The 'thinner' the air becomes, the harder it is for the human body to function normally. This is especially true if the ascent has been rapid. 

As a result, breathing can become deeper and more rapid, the pulse quickens, and ankles and hands may swell.

Mild Symptoms of AMS

Some, or all, of the range of AMS symptoms can appear within several hours of arrival, or up to three days later. These may include:

  • Shortness of breath during exertion
  • Headache
  • Loss of appetite
  • Dizziness
  • Nausea/vomiting (common in children)
  • Sleeping difficulties

For most people, these symptoms ease completely when they acclimatise by spending several days at the same altitude. If symptoms do not abate, descending to a lower altitude generally sees symptoms disappear.

It is important not to go higher if you have ANY symptoms of altitude sickness.

Severe Symptoms of AMS

While AMS is generally benign and short-lived, it can progress to one of two potentially fatal forms of altitude sickness. These severe forms of AMS include High Altitude Cerebral Oedema (HACE) and High Altitude Pulmonary Oedema (HAPE). These symptoms include:

  • Shortness of breath while resting
  • Frothy sputum
  • Vomiting
  • Confusion

High Altitude Cerebral Oedema (HACE) affects the brain. Confusion is an early sign and may lead to coma and death.

High Altitude Pulmonary Oedema (HAPE) affects the lungs. Difficulties with breathing lead to low oxygen levels in the body, followed by respiratory failure and death.


The key to preventing AMS is gradual acclimatisation. Ascend slowly, no more than 500 vertical metres a day, with a rest day included after every additional 1000m you ascend.

It is also advisable to:

  • Sleep at a lower altitude than the height reached during that day’s ascent.
  • Eat light, high-carb meals for extra energy.
  • Avoid alcohol. It increases urine output and causes dehydration.
  • Take medication as directed by your travel doctor.
  • Drink additional fluids. Mountain air is cold and dry and moisture is lost with every breath. Drink enough water and safe fluids to ensure a strong flow of clear urine. If signs of dehydration are present, take extra doses of oral rehydration solution or water.
  • Avoid sedatives.

Rapid ascent is the main contributing factor in AMS at altitudes of 2400m or above. If trekking or climbing above 4500m, the ascent should be well-planned. Climbers should have access to treatment medication for both HACE and HAPE.

Recreational Diving

Exploring coral reefs, sunken ships and the magnificent marine life of our oceans and seas is a wonderful way to relax on holiday.  For many this is the main reason for travel, while others will just like to have a brief dive while enjoying a new beach resort or holiday destination.

Generally, the preparations that a traveller should do for their holiday, is not affected by the activity of diving, but a couple of notable exceptions arise:

  1. Itineraries need to planned around allowing plenty of time after the last dive, to allow any nitrogen to escape from the body, before a diver flies in a pressurised airplane, which means most commercial flights. This is particularly important after deep diving. Remember the rule - don’t fly for 24hrs after diving.
  2. Some antimalarials can be a problem. The commonly prescribed medication, antimalarial, can predispose a small percentage of people to a photo-sensitivity reaction (an excessive sunburn). While this is avoided by covering-up, and wearing blockout, divers should be alert to this if traveling and diving in malarias regions and discuss your options with a travel doctor prior to departure.
  3. The ability to "equalise" the pressures of the middle-ears to allow safe diving is important, and travellers with colds or allergies may need specific advice and treatment for this.

Select Travel Doctor-TMVC clinics provide medical assessments for recreational diving and many of our doctors are registered as SPUMS members, qualified to perform these assessments for certification of student and re-certifying divers.

Commercial Diving

Travel Doctor-TMVC has select sites that can provide formal medical assessments for Commercial Diving certificates. This has required specialised training and is not offered in every clinic. Contact your closest clinic for specific details.

Coral Cuts

Coral cuts are common among surfers, divers, and snorkelers. It is important to treat marine wounds quickly as they can become severely infected if left untreated.

Symptoms: Initially the wound may look clean and feel minor and may even go unnoticed only to start stinging and become red within hours.