Merck Manual

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Specific Medical Conditions and Travel


Christopher Sanford

, MD, MPH, DTM&H, University of Washington;

Alexa Lindley

, MD, MPH, Department of Family Medicine, University of Washington

Last full review/revision Jul 2020| Content last modified Jul 2020
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NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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Topic Resources

People with certain medical conditions encounter special problems in transit.

Heart Disease and Travel

If people with angina, heart failure, or heart rhythm disturbances have symptoms during rest or with minimal exertion, they should not travel. If people recently have had a heart attack, they are advised to postpone travel for a variable period of time, depending on the severity of the heart attack. They should ask their doctor whether they need to wait and, if so, for how long. People with severe or worsening angina should avoid flying. Their symptoms may worsen because less oxygen is available in the cabin of airplanes traveling at high altitudes.

All travelers with heart disease should carry a copy of a recent electrocardiogram (ECG). People with pacemakers, implantable defibrillators, or coronary stents should carry a card or doctor’s letter documenting the presence, type, location, and electronic characteristics of the implanted device. An implanted metal device may trigger an alarm as the person passes through electronic security. Electronic security devices do not generally affect implantable defibrillators, but travelers are advised to avoid standing in walk-through metal detectors for more than 15 seconds. Hand-held metal detectors are also safe for people with defibrillators, but prolonged contact, such as holding the detector over the defibrillator for more than 5 seconds, should be avoided.

If given notice in advance, most major airlines can provide low-sodium, low-fat meals on flights with regular meal service. If notified in advance, many cruise lines can also provide these meals.

Did You Know...

  • At high altitudes, symptoms of certain heart and lung disorders and sickle cell anemia can worsen because less oxygen is available.

Lung Disease and Travel

Travelers with lung cysts, severe emphysema, a large collection of fluid around the lungs (pleural effusion), recent lung collapse (pneumothorax), or who have had recent chest surgery can develop complications caused by airplane pressure changes. They should not fly without approval from their doctor.

Other travelers with lung disease may need supplemental oxygen while they are aboard an airplane. A doctor determines a person’s need for in-flight oxygen by measuring the level of oxygen in the blood. A low level of oxygen in the blood is called hypoxemia. Most airlines will provide in-flight oxygen if they are given a doctor’s prescription and advance notice. Travelers are not allowed to carry oxygen in any form aboard an airplane. Travelers who need oxygen during airport layovers must make their own arrangements, although most oxygen vendors will assist their regular customers without charge if they have services in the destination city. Other respiratory equipment, such as continuous positive airway pressure devices, can be accommodated on an airplane provided the equipment does not exceed the size allowed for carry-on luggage. However, travelers who need this equipment should allow extra time for security checks.

Ground travel at high altitudes may present special problems because less oxygen is available than at sea level (see Altitude Illness). In general, people with mild or moderate lung problems do not have any difficulty at altitudes below 5,000 feet (1500 meters), but the higher the altitude, the greater the chance of problems. People with lung disease traveling in or through such areas should take the same precautions they would take if they were flying.

Bus, train, car, and ship travel is safe for people with lung disease but requires planning to ensure a supply of oxygen. Commercial services can coordinate oxygen deliveries for travelers anywhere in the world.

People with asthma, emphysema, or bronchitis may find that their symptoms worsen in cities where air pollution is significant. They may need additional treatment with their inhalers or additional drugs, such as corticosteroids, to control symptoms adequately. Smoking can make mild hypoxemia worse and should be avoided before flying. The effects of alcohol may be increased by hypoxia and fatigue, and therefore alcohol is best avoided while traveling.

Diabetes and Travel

Blood sugar levels are best managed in transit by frequent testing, with adjustments of food intake and drug doses as needed. Travelers with diabetes should pack sugar (glucose) supplements in their carry-on bags or carry juice, crackers, and fruit for when blood sugar levels are low. Generally, the timing of insulin doses should be based on how much time has elapsed during travel rather than on local time. Also, if travel plans incur time changes of more than a few hours, people with diabetes, especially those taking insulin, should consult with a doctor about how best to schedule their drugs. Insulin can be stored without refrigeration for many days but should be kept out of extreme heat.

If given 24 hours' notice, most major airlines provide special meals for people with diabetes. Measures to prevent dehydration while in flight are important.

Did You Know...

  • When people with diabetes are traveling, to avoid hypoglycemia, target blood sugar levels should be slightly higher than when not traveling.

Blood sugar levels should be monitored frequently on arrival because activities and diet often differ from those at home. Because controlling blood sugar levels precisely is more difficult while traveling, levels tend to vary more than usual. Trying to keep levels very close to normal thus increases the risk that levels may sometimes become too low. For this reason, target blood sugar levels should be somewhat higher than ideal while traveling. Diabetic travelers should adhere to established diets despite temptations to try new foods and to eat more frequently or off schedule. They should wear comfortable socks and shoes, check their feet daily, and avoid walking barefoot to prevent minor injuries that may become infected or be slow to heal.

Pregnancy and Travel

Pregnancy is generally not affected by flying on a jet. However, pregnant women who are close to their due date (over 36 weeks gestation) and those at risk of miscarriage, premature delivery, or placental abruption should avoid flying and traveling long distances. Most airlines have policies regarding travel for pregnant women, and these policies should be checked before tickets are purchased. For instance, an airline may require that a woman in her 9th month of pregnancy who wants to fly must have a doctor's written approval letter dated within 72 hours of departure that states her expected delivery date. Pregnant women traveling long distances should take precautions to reduce the risk of blood clots (such as getting up often when traveling by airplane and stopping to take short walks when traveling by car) and dehydration. Seat belts should be fastened below the abdomen and across the hips to prevent injury to the fetus.

Pregnant women should avoid live vaccines, including yellow fever, measles-mumps-rubella, varicella (chickenpox), and typhoid fever by mouth (see table Vaccines for International Travel).

Pregnant women should avoid prolonged use of water purification tablets that contain iodine because iodine can affect development of the thyroid gland in the fetus.

Pregnant women who cannot postpone travel to regions of the world where malaria is common must weigh the risks of taking protective drugs whose effects on pregnancy are not well known against those of traveling without adequate protection. Pregnant women should consider delaying travel to areas where malaria is common because malaria is more likely to be serious and life threatening among pregnant women than among women who are not pregnant, even when preventive drugs are used. Mefloquine for malaria prevention is approved for use during all 3 trimesters of pregnancy.

Pregnant women are also at risk of contracting hepatitis E infection, a viral liver infection rare in the United States but common in Asia, the Middle East, North Africa, and Mexico. Miscarriage, liver failure, or death may result. There is no treatment, so postponing travel to regions where hepatitis E is common should be considered. Women who cannot postpone travel should be vigilant about hand washing and following safe food guidelines (see Gastroenteritis : Prevention).

Pregnant women should not travel to areas with risk of Zika infection.

Other Conditions

Travel and transit also affect other medical conditions such as

  • Sickle cell disease

  • Human immunodeficiency virus (HIV) infection

  • Colostomy

  • The wearing of contact lenses

  • Mental health disorders

  • Physical disabilities

  • Jaw problems

Some travelers with sickle cell disease are at risk of having pain (sickle cell crisis) when exposed to the low humidity and low oxygen levels in airplane cabins. This risk can be minimized with adequate hydration and oxygen.

Drugs used to treat human immunodeficiency virus (HIV) infection or AIDS may interact with drugs frequently taken by international travelers to prevent malaria and traveler’s diarrhea. Therefore, affected travelers should discuss the risk of such interactions with their doctors and pharmacist.

People with a colostomy should wear a large bag or bring extra supplies because fecal output may increase with expansion of intestinal gas during flight. Because gas expands in flight, water should be substituted for air in devices secured by air-filled cuffs or balloons, such as feeding tubes and urinary catheters.

People who wear contact lenses may want to wear eyeglasses en route or wet their lenses frequently with artificial tears to compensate for low humidity in the airplane. Artificial tears may also be helpful for people with dry eyes. In general, bringing an extra set of eyeglasses or lenses or a prescription in case replacements are necessary is a good idea. Extra batteries for hearing aids may also be useful.

Travelers with serious mental health disorders, such as poorly controlled schizophrenia, may pose a risk to themselves or others and should be accompanied by a responsible attendant. Sedating drugs may be recommended also.

Most airlines provide disabled travelers with wheelchairs and stretchers on commercial flights. Some airlines accommodate travelers who need special equipment, such as intravenous lines or ventilators, as long as trained personnel accompany them and arrangements have been made in advance. If travelers cannot be accommodated on a commercial flight because of severe illness, air ambulance service is necessary.

People whose jaw is wired shut (as occurs after surgery on the jaw) should not fly unless they have a way to quickly open the jaw. If they vomit while the jaw is wired shut, they could choke or inhale vomit.

General advice about traveling with various medical conditions can be obtained from

  • The medical departments of major airlines

  • The Federal Aviation Administration (

  • Online travel information sources

  • Local travel clinics

More Information

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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