Talk to your doctor. See if your doctor suggests anything to avoid or special precautions.
Do research. What triggers will you encounter when you're away? Remember that pollen seasons vary in different parts of the country and world. Check weather and pollen forecasts and plan your trip around them.
Choose the right place to go. If pollen is your problem, go to the beach -- pollen counts are low on the coast. Dust mites are rare in the mountains, since they don't like elevations above 2,500 feet. Low temperatures kill mold.
Be picky when booking a room. Ask for a non-smoking room and make sure that your hotel doesn't accept pets. See if you can get a room with bare floors, since carpet traps allergens. Make sure your room has AC, since it will filter out pollen and mold.
Get medical ID jewelry. If you have a life-threatening allergy, get a necklace or bracelet that says what you're allergic to.
Packing Your Bag
Medical kit. Always carry a bag with any allergy supplies you need -- antihistamines, decongestants, eye drops, skin creams, tissues, and cough drops. Make sure all your medicines are in their original bottles -- this will save you trouble at airport security. Keep the kit in your carry-on bag.
Epinephrine. If you have a serious food or insect allergy, pack two epinephrine injection kits for emergencies.
Pillow. Bring your own, preferably with a dust mite-proof pillowcase. You may want to bring your own mattress cover, too.
Information about your allergies. Have info about your allergies that you can hand out to restaurant or hotel staff. If you're in a foreign country, make sure it's in the local language.
Making the Journey
Traveling by Car. Keep your windows rolled up. Use your air conditioner to filter the air. Don't rent a car that anyone's smoked in. Travel in the early morning or late evening, when pollen counts are lower and there's less traffic.
Traveling by Air. Take an antihistamine before you board the plane. If you have food allergies, notify the airline before, or eat only safe snacks that you packed. Stay hydrated by drinking plenty of fluids and avoiding alcohol.