There are no particular health concerns associated with travel to Turkey. For information and updates on any epi- or pandemics (such as avian influenza or the H1N1 swine flu), visit the websites of the World Health Organization (www.who.int), the European Centre for Disease Prevention and Control (http://ecdc.europa.eu), or the United States Centers for Disease Control (www.cdc.gov).
General Availability of Health Care -- Any veteran traveler never leaves home without a basic health kit tailored to his or her particular needs. Generally, these should include anti-diarrheal medicine such as Imodium, aspirin, ibuprofen sunscreen, insect repellant, and sanitary products. While it is imperative to pack prescriptions that you need (insulin, cholesterol-lowering meds, et al), many are widely available in pharmacies (called eczane) in Turkey, sold by the brand name at prices often lower than at home. If you suffer from a chronic illness, consult your doctor before your departure. Pack prescription medications in your carry-on luggage, and carry them in their original containers, with pharmacy labels -- otherwise they won't make it through airport security.
What to Do If You Get Sick Away form Home -- Any local consulate can provide a list of area doctors who speak English. If you do get sick, you may want to ask the concierge at your hotel to recommend a local doctor, even his or her own. This will probably yield a better recommendation than any information number would. In fact, ask anybody on the street and he/she will likely accompany you to the doctor. Also, local doctors advertise their services through discreet signs near their offices, and most speak English.
Dietary Red Flags -- Food poisoning and diarrhea are probably the most prevalent illnesses associated with travel to Turkey. Although water from the tap is chlorinated and generally safe to drink, even the locals drink bottled water. Avoid nonpasteurized dairy products and shellfish during the hot summer months, and maintain a healthy suspicion of street vendors. In the event that you become ill, drink plenty of (bottled) water and remember that diarrhea usually dissipates on its own. Pepto Bismol (bismuth subsalicylate) can often prevent symptoms, but if the problem becomes truly inconvenient, pharmacists are generally sympathetic and bilingual, and will be able to provide an effective remedy. (Ercefuryl works wonders.)
Bugs, Bites & Other Wildlife Concerns -- Rabies is endemic in parts of Turkey, and joggers have been known to be bitten by infected strays. But this is extremely rare. Best to stay away from animals altogether -- advice that, given the sweet temperaments of the street dogs and cats, I myself am incapable of following. If you're concerned, consult your doctor for pre-exposure immunization.
Tropical Illnesses -- Although the persistence and tenaciousness of Turkish mosquitoes might cause you to suffer, it is unlikely that malaria will. Keep in mind that you're more likely to catch deadly mosquito-borne diseases in your own backyard than abroad. If you are experiencing symptoms, seek prompt medical attention while traveling as well as for up to 3 years after your return. Don't forget to pack a proven insect repellent (especially for those nights lounging outdoors in a tea garden or spent waterside along the coast).
Newbie Western travelers to Turkey are often plagued by worries over safety: It is a Muslim country, after all, and there is a war going on nearby, right? Well, no actually. While Turkey's population is mostly Muslim, I'm sure I don't need to remind you that all Muslims aren't terrorists, do I? Tsk tsk, if I do. Indeed, I guarantee that one of the first impressions that will overwhelm you upon arriving in Turkey is its complete and utter "normalcy."
Second, there's a war going on, right? Sure, but it's 1,600km (994 miles) away as the crow flies. And as we've all so regrettably learned, distance doesn't contain conflict, and the violence in Iraq menaces us all just as much in London, Toronto, and New York as it does in Istanbul.
Okay, but what about the PKK? Sigh. Radicals committed to violence (in this case, right-wing Kurdish nationalists) are attacking Turkish soldiers in the southeast of the country. Infrequently, the violence erupts beyond these borders. In my opinion, such an attack targeting foreign tourists would be a strategic mistake; still, it might be a good idea to check in with your appropriate travel advisories. In the U.S., log onto http://travel.state.gov/travel; in the U.K.: www.fco.gov.uk; in Canada: www.voyage.gc.ca; in Australia: www.smartraveller.gov.au; in New Zealand: www.safetravel.govt.nz.