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What is altitude illness?

mountain.jpgAltitude illness is a condition which occurs in many travelers making rapid ascents to high altitudes. It is commonly referred to as acute mountain sickness (AMS). It most often occurs at altitudes of 3,000 meters (approximately 10,000 feet) or more. In some individuals, it has been reported as low as 2,500 meters (8,000 feet).

We suspect that altitude illness is caused by the body's reaction to lower levels of oxygen found at high altitudes. The disease may occur several hours to days after ascending to high altitudes. Symptoms range from mild to severe.

Classic, high risk areas of the world for altitude illness include any mountain range over 10,000 feet, such as the Alps, Andes, or Himalayas. In addition, travelers to areas of North American, East Africa, and the polar regions are at risk.

Symptoms of altitude illness

Altitude illness can range from mild to severe.

Mild symptoms

  • Headache
  • Fatigue
  • Sleep disturbance
  • Appetite loss
  • Nausea
  • Difficulty breathing

Severe symptoms

  • Shortness of breath while resting
  • Rapid pulse at rest (>100-110 beats per minute or BPM)
  • Decreased urination
  • Visual changes
  • Severe headache
  • Loss of coordination
  • Mental confusion
  • Productive cough

The last group of symptoms may represent fluid accumulation in the brain (high altitude cerebral edema) or lungs (high altitude pulmonary edema). In these severe cases, the disease can be fatal if not treated rapidly and requires descent to lower altitudes. Luckily, in most travelers, altitude illness is mild and does not become severe.

Asthma does not increase the risk of altitude illness. In fact, people with asthma often do well at altitude since there is less pollution in the air.

Prevention of altitude illness

The best prevention is slow ascent. In general, ascent of altitudes of no more than 1,000 feet (300 meters) per day above 10,000 feet is recommended. Upon arrival at altitude, you should avoid strenuous activity until you fully acclimatize.

Maintain fluid intake to avoid dehydration and follow the maxim, "climb high and sleep low." Avoid alcohol, cigarettes and sedatives (including narcotics).

Use of coca tea or coca leaves

The active ingredient in coca leaves is a mild stimulant that may help you stay alert and hydrated. This may make you feel better at altitude. Unfortunately, it does not prevent altitude illness.

coca.jpgGingko biloba or Viagra™ (sildenafil)

It is unknown whether these two medications are effective in preventing altitude sickness, and therefore, their use is not recommended.

Fitness level

Physical conditioning does not protect against altitude illness. Susceptibility is based on your body's response to altitude and is not reflective of aerobic capacity.

Treating altitude illness

If slow ascent is not possible or if you have a history of recurrent altitude illness, preventive medications may be needed. An example is Mt. Kilimanjaro (19,340 feet), which is often climbed in less than seven days.

Acetazolamide (Diamox)

The drug of choice to prevent altitude illness is acetazolamide. Take this medication 24 hours before ascent above 10,000 feet through 24-48 hours after you reach peak altitude. Avoid this medication if you have a history of sulfa antibiotic allergy, liver or kidney disease, or severe lung disease. Acetazolamide may cause tingling of the lips, fingers and toes, frequent urination, and a metallic taste with carbonated beverages.


If you cannot take acetazolamide, dexamethasone can be used. If you've had adverse reactions to steroids or have diabetes, this drug may not be safe for you. Dexamethasone can cause headaches, nausea, dizziness, abdominal pain, and can suppress your immune function if used over a long period of time.

Treating severe altitude illness

If symptoms of acute mountain sickness develop, you should stop your ascent, rest and get adequate fluids and calories. If altitude illness symptoms worsen, rapid descent to lower altitudes should begin as soon as possible. You should also see a medical professional.

Oxygen, use of hyperbaric chambers and medications may be needed.

Additional resources


Authored by: Hall Health Center Travel Clinic staff

Reviewed by: Hall Health Center Travel Clinic staff (AT), May 2014

Traveler's diarrhea is the most common infectious disease experienced by international travelers. It can be caused by bacteria (most common), viruses or parasites that have been ingested through contaminated food or drink. Traveler's diarrhea can be mild to extreme in severity.

Preventing traveler's diarrhea

Remember: boil it, cook it, peel it, or forget it! In other words, if you don't boil, cook, or peel your food, you could get sick.

Other prevention tips include:

  • Wash your hands with soap and water or use alcohol-based hand sanitizers before eating.
  • If you're having coffee, tea, or other drinks that require water for preparation, use bottled or disinfected water.
  • Don't use tap water for drinking or brushing your teeth, and be sure to avoid ice. Drink bottled water with an intact seal or purify water yourself.bottled water.jpg
  • Avoid unpasteurized dairy products.
  • Avoid food of questionable preparation or origin (like buffets).
  • Avoid food from street vendors.
  • Steer clear of food that has been rewarmed (like quiche).
  • To clean vegetables, start with boiled water, and add bleach (2-4 drops per liter of water). You may also use enough iodine tablets to make the water the color of dark tea. Soak veggies in the water for several hours, and then drain produce and rinse again with clean water.

Treating traveler's diarrhea

Traveler's diarrhea can range from mild to severe. Treatment varies based on severity.

Mild diarrhea

Mild traveler's diarrhea is characterized by 3-4 unformed stools in 24 hours with mild cramping.

intestines.jpgRecommended treatment:

  • Drink plenty of clear fluids or consider the use of Oral Rehydration Solution (ORS) or Ceralyte. (Appropriate for adults and children.)
  • Loperamine (Imodium AD) will decrease diarrhea for about 4 hours, allowing you to travel or sleep. Follow the directions on the box of loperamine. Not to be used for children under 12 or if you have bloody diarrhea.
  • Try to eat as soon as possible. It's best to start with easily digested foods, like bananas, rice, applesauce and toast. Avoid milk products for 72 hours after last diarrhea.

Moderate diarrhea

Symptoms of moderate traveler's diarrhea include increased frequency of unformed bowel movements with one or more of the following: Fever up to 101° F, abdominal pain, nausea or vomiting.

Recommended treatment:

  • Drink plenty of clear fluids or consider the use of Oral Rehydration Solution (ORS) or Ceralyte. (Appropriate for adults and children.)
  • Loperamine (Imodium AD) will decrease diarrhea for about 4 hours, allowing you to travel or sleep. Follow the directions on the box of loperamine. Not to be used for children under 12 or if you have bloody diarrhea.
  • Prior to your trip, an antibiotic will be prescribed for you depending on your history and destination. It is important to discuss all your medications with your provider before taking antibiotics, as some drugs reduce the efficacy of antibiotics, or cause unpleasant side effects:
    • Ciprofloxacin (Cipro), which should be taken in conjunction with Loperamine (Imodium AD). Not to be used in pregnant or breastfeeding women, or in children under 18.
    • Azithromycin (Zithromax), the preferred medication for children under 18. It may be dispensed as a powder to allow a parent or guardian to administer it as a liquid. Azithromycin should be taken with food to avoid stomach upset.
    • Rifaximin (Xifaxan), which is used for individuals who are not able to tolerate other antibiotics.

Severe diarrhea

Severe traveler's diarrhea is moderate diarrhea with or without abdominal cramping/pain, fever, blood in stool, dehydration. You can take antibiotics if you have severe diarrhea, but if symptoms worsen seek medical care. These symptoms could indicate a more severe infection, such as giardia or amoebiasis.

Diarrhea in children

Young children (under age 5) are particularly susceptible to becoming dehydrated from diarrhea. Do not use loperamine (Imodium AD) in children.

If a breastfeeding infant has diarrhea, continue breastfeeding. An infant or toddler should have at least one wet diaper every 4-6 hours. If there is a longer period between wet diapers, the child needs more fluids and should be seen by a health care provider. Parents and guardians should have a low threshold for seeking medical help if a child in their care experiences vomiting and diarrhea.

Additional resources


Authored by: Hall Health Center Travel Clinic staff

Reviewed by: Hall Health Center Travel Clinic staff, May 2014

Medical Assistant (MA)

Schedule before you travel

Because several weeks may be required to complete a needed vaccine series, we recommend you come in for the initial appointment at least 4-6 weeks before your departure date. You should telephone for an appointment two weeks before that, if possible.

Before you travel or study abroad it’s important that you understand possible risks to your health and take appropriate precautions specific to your destination overseas. You can schedule a travel consultation at the UW Medicine Travel Clinic Hall Health Center prior to your study abroad program or any other world travel. Our travel health experts can inform you about:


During a typical pre-travel consultation, the following issues related to type of travel and destination are discussed.

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