If you have allergies or asthma, you know they're always with you, even when you travel. To ensure that your next trip is relaxing and enjoyable, plan ahead for the changes in your environment that may affect your allergies or asthma.

Traveling ...By auto, bus or train When traveling by auto, bus or train, potential irritants or allergens can include dust mites, indoor molds, pollens and other substances.

Common allergens such as mites and molds can lurk in the carpeting, upholstery and ventilation systems of vehicles. Before beginning a lengthy auto trip, try turning on the air conditioner or heater and open the windows for at least 10 minutes prior to entering the car. This will help remove dust mites and/or molds that may be in the system.

Outdoor allergens, such as pollens and molds, are also potential hazards, especially when traveling with open windows. If you have been diagnosed with pollen or mold allergies, close your windows and turn on the air conditioning instead.

Cigarette smoke or outdoor air pollution can worsen allergy and asthma symptoms. To avoid excess air pollution when traveling by automobile, travel in early morning or late evening, when the air quality is better and you can avoid heavy traffic. If you use a nebulizer for your asthma, get a portable nebulizer that plugs into your car's cigarette lighter or uses a portable battery pack.

...By airplane Air quality on planes can greatly affect the allergic or asthmatic patient. While all domestic flights are now smoke free, many international flights are not. If traveling abroad, make sure you are seated as far as possible from the smoking section when getting a seat assignment.

If you have severe asthma and occasionally require supplemental oxygen, you may feel the need for additional oxygen at normal cruising altitudes of approximately 35,000 feet. If you think you may need supplemental oxygen, you must arrange for this with the airline well before the flight. No one can be refused travel for needing supplemental oxygen; however, this has to be arranged in advance.

If you have food allergies, be extremely cautious when eating airline food. Since the food comes from a vendor, no one on board may be able to tell you the specific ingredients of the foods. Make sure to carry your portable, injectable epinephrine in case you have a severe reaction while in flight.

If you have sinusitis, or a sinus or ear infection, air travel could cause significant pain. Try to delay your travel until your symptoms improve. If you usually experience severe ear or sinus pain while flying, take a short-acting oral decongestant or use a nasal spray decongestant about one hour before takeoff. In flight, sipping liquids, swallowing often and chewing gum may help decrease any pain. The air in planes is very dry. Use saline nasal spray once every hour to keep your nasal membranes moist. This will help you to be more comfortable during and after your flight.

...By ship When making cruise reservations, if you have severe asthma and/or allergies, ask about the qualifications of medical personnel and the availability of adequate medical care while on board the ship. Again, if you have food allergies, make sure to bring your injectable epinephrine for any possible severe allergic reactions.

If you have the skin condition eczema, be forewarned that increased exposure to water and sun can aggravate it. You may get some protection by liberally lubricating the skin with medicated ointment or over-the-counter lotion.

Keep in mind that when traveling, the climate and the season of your destination will also dictate your specific allergen and irritant exposure. In tropical, damp climates, you may have increased exposure to allergens such as mites, airborne molds and specific pollens. In cold, damp climates, you may be exposed to more house dust mites and indoor molds. Cold air in frigid, dry environments can also be an irritant for people with asthma.

Allergen sources Many travelers stay at hotels. Hotel rooms, however, often contain large concentrations of dust mites and molds in carpeting, mattresses and upholstered furniture that can worsen your allergy and asthma symptoms. Irritant fumes from cleaning products may also cause problems.

When making hotel reservations, ask if there are allergy-proof rooms available. If you are sensitive to molds, request a sunny, dry room away from areas near indoor pools. Also, if you have allergies to any animals, inquire about the hotel's pet policy, and request a room that has been pet-free. People who are allergic to dust mites may want to bring their own dust-proof, zippered covers for pillows and mattresses, or personal bedding.

If staying in a cottage or cabin in a forest or near a beach, make sure to have it thoroughly cleaned and aired-out before you arrive. This can reduce dust mite and mold concentrations.

Visiting family and friends Indoor environmentsespecially during the holidayscan be significant sources of potentially allergic hazards. Dust mites on Christmas ornaments and decorations; molds on Christmas trees, wet leaves and logs for wood-burning stoves; and strongly-scented potpourri, candles and air fresheners may all trigger allergy or asthma symptoms. Heating vents may also blow accumulated dust mites and molds.

Animal allergens, found in pets' dander, saliva or urine, can sometimes be a problem, even if the pet has been put outside or removed from the room. It takes months before the allergic residue of an indoor pet may no longer cause symptoms, so it's best to avoid staying in the homes of family or friends whose pets trigger your allergy symptoms.

People with food allergies should be careful about eating holiday treats, any of which may contain hidden, significant food allergens such as peanuts, tree nuts, eggs, milk, wheat or shellfish.