Ultimate Everest - The #1 Guide Service to Everest Base Camp

Lake Louise Scoring System (LLSS)
for Acute Mountain Sickness (AMS)

The Lake Louise Scoring System (LLSS) was designed to evaluate adults for symptoms of acute mountain sickness (AMS). The system uses an assessment questionnaire and a scorecard to determine whether an individual has no AMS, mild AMS, or severe AMS. (Note that LLSS does not have a category for moderate AMS.)

While on your trip, our guides will ask you to perform an assessment twice per day. The guides will use LLSS, along with pulse oximeter readings and other criteria, to monitor your condition. LLSS is an objective measure that our staff can use to evaluate your health during your climb.

A diagnosis of AMS is based on the following conditions:

Self-Assessment Questionnaire


Gastrointestinal symptoms:

Fatigue and weakness:

Dizziness and lightheadedness:

Difficulty sleeping:

A total score of 3 to 5 indicates mild AMS. A score of 6 or more signfies severe AMS.

The presence of mild AMS is very common and does not necessarily mean that you will need to descend. On the other hand, an assessment of mild AMS does not preclude you from being turned around either. LLSS is one tool, out of many, that we use to make that determination. Although we would like everyone to complete the trip, our primary responsibility is keep you safe.

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