Dr. Richard Pfleger, a consultant for Barny's, a Czech company that imports a product called ActivAloe, notes that the most common problems — sunburn and dehydration — are easily preventable. "Wear sunscreen and a hat," he advises, "and remember to drink lots of water."

Professor Adolf Slabý, a faculty member of the 4th Medical Faculty at Charles University and a volunteer doctor at Health Centre Prague, agrees. "Wear sun lotion with a high UV [filter] and drink a lot of nonalcoholic beverages," he says.

Pfleger also has words of advice for the very young and the very old. "The elderly are more susceptible to dehydration, and children's skin is more sensitive," he says. "Parents need to make sure children wear sun lotion, and older people need to make sure they drink enough water."

Dr. Barbara Taušová, a pediatrician at Canadian Medical Care, reminds parents to make sure they cover all their children's sun-exposed skin. "Don't forget the ears," she says.

On hot, humid days, dehydration isn't the only thing that can spoil your fun. Slabý warns of heart problems associated with strenuous activity in the heat. "Avoid exercising on hot, humid days," he cautions, "even if you are fit and healthy."

Colds and the flu are typically wintertime troubles, but they can develop in stressful situations during warm weather, too. "On holiday, many people get tired from long bus rides and doing too much," Slabý says. "This decreases your immunity, and you get sick." His advice? "Avoid sick people and don't overstrain yourself."

Leg problems can also affect some people on long trips. "On days you're traveling a lot, don't forget about body stretching," says Milena Piraličová, product manager for Boehringer Ingelheim, an international pharmaceutical company. "People suffering from chronic vein insufficiencies may notice more problems in the summer heat."

There are some things you can do to prevent such problems, or at least alleviate your symptoms. "Wear comfortable clothes and shoes, and it may help to raise your legs," Piraličová recommends. "If you suffer from varicose veins or pain in your legs, the drug Antistax may relieve the symptoms."

Other all-too-frequent holiday illnesses — gastrointestinal disorders such as indigestion, abdominal pain, vomiting or diarrhea — are usually a result of eating or drinking something you shouldn't have. "You need to be careful with food and water while traveling," advises Taušová.

Food poisoning and traveler's diarrhea are quite common when visiting a foreign country, notes Slabý. "You can get these diseases from contaminated water or food, insects and unclean hands," he says. "Prevent it by carefully choosing food and drinks, washing your hands and protecting food from flies or rodents."

Bugs are truly unwelcome summer holiday guests. In the country, being outdoors brings the risk of contracting a tick-transmitted infection. Lyme disease, which you get by being bitten by an infected tick, is a problem in the Czech Republic, though not necessarily a reason to panic. "If the tick is removed within 12 hours, the risk of infection is practically zero," Slabý says. "Cover the tick with oil or cream, remove it and apply an antiseptic to the skin."

Taušová recommends wearing clothes that cover your arms and legs and tucking your pants into your socks. "Check the entire body for ticks after being in the woods," she adds. "Don't forget the scalp and behind the ears and knees."

Ticks aren't the only bugs waiting to take a bite out of you. Mosquitoes, bees and wasps are also out there. Insect repellent will do the job in most cases, according to Taušová. "But bee and wasp stings can be very dangerous for people who have an allergic reaction to them," she warns.

Taušová recommends wearing shoes outside in case you step on a bee, avoiding sweet foods and drinks that attract bees and wasps, and not waving your hands at them to make them go away. "It makes them angry," she says. "Just stand still and they should go away."