(MONEY Magazine) – You're headed for Shanghai to tour some factories or to Tanzania for a weeklong safari. Or perhaps your son or daughter is spending a semester in Madras or spring break in Belize. You check with your general practitioner or the Centers for Disease Control and Prevention (CDC) to find out the recommended vaccinations, and you're set, right? Not necessarily. If you really want to avoid getting sick on your next trip abroad, you should visit the right pro before you leave.

Travel doctors, though relative newcomers to the medical scene, are busy people these days. Americans are winging their way around the world like never before in pursuit of business, pleasure and adventure in ever more remote destinations. They are traveling in increasing numbers to places where medical care is substandard, food and water is highly contaminated, blood isn't screened, and biting insects carry deadly diseases. And they're bringing home more mementos than just postcards and knickknacks. Consider the souvenir illnesses that Dr. Mary Wilson, director of the Travel Resource Center at Mount Auburn Hospital in Cambridge, Mass. sees: Traveler's diarrhea, respiratory infections and influenza are the most common. Among more serious illnesses, malaria, typhoid and dengue fever show up the most. Amoebic dysentery, hepatitis and schistosomiasis, a parasitic disease, are more unusual. Leishmaniasis, a potentially disfiguring skin ailment transmitted by the bite of a sandfly, is still more unusual but is on the rise.

Here's why it pays to see a specialist before you set off for an exotic locale, plus advice on how to find the right expert, a look at what you'll spend and suggestions for basic medical supplies to take with you.

The value of advice

Before you depart, you can research your destination at the CDC website (www.cdc.gov), where you'll find comprehensive information on medical threats and recommended vaccinations, listed by region. For country-specific vaccination requirements, go to the World Health Organization (WHO) site (www.who.int/ith/english/country.htm). But navigating the thicket of CDC and WHO advisories and applying them to your itinerary is best done by a specialist. If you look up Peru, for example, at the CDC site, you'll read that hepatitis A and B, rabies, typhoid, yellow fever, malaria and dengue fever are all risks. But a businesswoman staying in Lima for a week is more likely to come down with dengue than malaria, notes Dr. David Shlim, director of Jackson Hole Travel and Tropical Medicine and a pioneer in the travel-medicine field. And a trekker on Peru's Inca Trail faces a very different set of concerns than an ecotourist in the Peruvian Amazon.

There's no single guide to exactly what you need for each destination, says Shlim, which makes it easy for a nonspecialist to overtreat. That can be costly and can involve unnecessary discomfort. "I've seen a number of trips ruined by adverse reactions to malaria medication that people didn't even need," says Shlim.

A good travel physician (or trained nurse) will discuss your medical history and itinerary with you at length before taking up any needles and will help you weigh the benefits of each vaccination and medication against its cost and possible side effects. For example, Lariam, a controversial antimalaria drug, can cause depression, psychosis and anxiety in a small number of patients.

For older or disabled travelers, consulting with a travel physician can put challenging trips within reach. One regular patient of Dr. Bradley Connor, director of New York's Travel Health Services clinic, is a 65-year-old man with end-stage kidney failure who travels frequently to Tibet and Nepal to pursue Buddhist studies. He stops en route in Singapore for dialysis.

How to find a specialist

Finding a qualified travel physician--one who devotes a substantial portion of his or her practice to travel medicine--can be a challenge. The discipline is still so young that there's no medical school specializing in it and no examination to certify practitioners. To distinguish between a genuine specialist and a dabbler, stick with a doctor (or clinic) who belongs to the International Society of Travel Medicine (ISTM). First search the ISTM's website (www.istm.org) for someone in your area. Most people are within driving distance of one of the hundreds of good clinics now open, says Connor. Then follow up with questions.

Ideally, you want a specialist who has seen other patients headed for the same region--or has even been there. Many of these specialists are avid travelers and have firsthand experience of some of the most challenging of far-flung places. If you're going to Lhasa, Tibet, for example, you're better off seeing someone who knows the altitude.

What it will cost

A pre-travel consultation is suprisingly affordable: $35 to $90 for up to 90 minutes. Some managed-care plans now cover such appointments, along with some vaccinations. Many insurance plans will pay for shots only if they're administered by your primary-care physician. In that case, Connor suggests, discuss what you need with a travel specialist, then get the shots from your family doctor. Bear in mind that some of the priciest vaccinations--the one for Japanese encephalitis, for instance, can cost as much as $300 per course--are rarely necessary. The more routine injections for typhoid, hepatitis A and yellow fever seldom cost more than $90 each, and malaria prophylaxis runs from $5 to $10 a week (for every week that you are traveling in an area with malaria and up to four weeks afterward), depending on what drug is required. Even if your total vaccination bill seems like a lot, it's a small price to pay for health and peace of mind.

What to pack

You will likely leave the doctor's office armed with a shopping list of over-the-counter remedies, plus prescriptions for stronger stuff for an emergency. In the box on page 177, we've put together a $31 first-aid kit that should be your foundation. More often than not, says Connor, the ailment that ruins a trip isn't exotic or life-threatening, but all too familiar, like constipation, sinusitis or allergies.

To prevent most maladies, all you need are clean food and water and insect repellent. In fact, contaminated food and water can lead to one of the most common on-the-road complaints: traveler's diarrhea, which is typically characterized by abrupt onset and violent, unrelenting distress. If Imodium isn't enough, it's easily cured by the antibiotic norfloxacin or ciprofloxacin, which cost $5 to $15. It makes little sense to set off without some.

Depending on your destination, a travel doctor might suggest supplementing a first-aid kit with anything from sterile hypodermic needles and syringes--if you're heading to a country where they're typically reused--to chlorine tablets for water purification. (If you need sterile syringes, check out www.magellans.com, which sells, among other travel supplies, a $19.85 kit.)

If you're packing prescriptions, keep the medication in the original container with your doctor's name clearly visible. You'll avoid potential hassles at border crossings, where an unlabeled bottle can be a red flag, says Judy Kelly, head nurse at the UW Health-Physicians Plus Travel Medicine Clinic. Bring two doses of every prescription--one for your carry-on and one for your luggage--and store them in sealed plastic bags.

Finally, consider a medical evacuation insurance policy. (For more, see "A Painful Education," December 1999.) For just a few hundred dollars, you'll get financial and logistical help returning home if, despite all your preparations, you have a health emergency abroad.

Laura Stanley, a former editor at Travel Holiday, writes widely on travel and health.