The most common types of illnesses are caused by contaminated food and water. Make sure food has been thoroughly cooked and is served to you fresh and hot; avoid vegetables and fruits that you haven't washed (in bottled or purified water) or peeled yourself. If you have problems, mild cases of traveler's diarrhea may respond to Imodium (known generically as loperamide) or Pepto-Bismol. Be sure to drink plenty of fluids; if you can't keep fluids down, seek medical help immediately.
Infectious diseases can be airborne or passed via mosquitoes and ticks and through direct or indirect physical contact with animals or people. Some, including Norwalk-like viruses that affect your digestive tract, can be passed along through contaminated food. Condoms can help prevent most sexually transmitted diseases, but they aren't absolutely reliable and their quality varies from country to country. Speak with your physician and check the CDC or World Health Organization websites for health alerts, particularly if you're pregnant, traveling with children, or have a chronic illness.
Specific Issues in Spain
Medical care is good in Spain, but nursing can be perfunctory, as relatives are expected to stop by and look after patients' needs. In some popular destinations, such as the Costa del Sol, there are volunteer English interpreters on hand at hospitals and clinics.
In the summer, sunburn and sunstroke are real risks in Spain. Even if you're not normally bothered by strong sun you should cover yourself up, slather on sunblock, drink plenty of fluids, and limit sun time for the first few days. If you require medical attention for any problem, ask your hotel's front desk for assistance, or go to the nearest public Centro de Salud (day hospital); in serious cases, you'll be referred to the regional hospital.
Over-the-counter remedies are available at any farmacia (pharmacy), recognizable by a large green cross outside. Some will look familiar, such as aspirina (aspirin), and other medications are sold under various brand names. If you get traveler's diarrhea, ask for an antidiarréico (antidiarrheal medicine); Fortasec is a well-known brand. Mild cases may respond to Imodium (known generically as loperamide) or Pepto-Bismol. To keep from getting dehydrated, drink plenty of purified water or herbal tea. In severe cases, rehydrate yourself with a salt-sugar solution—½ teaspoon salt (sal) and 4 tablespoons sugar (azúcar) per quart of water, or pick up a package of oral rehydration salts at any local farmacia.
If you regularly take a nonprescription medication, take a sample box or bottle with you, and the Spanish pharmacist will provide you with its local equivalent.