Precooked ham, whether half, whole or canned, can be safely eaten from the package without further cooking, but if reheating a cooked ham is desired, it can be reheated in a 325 F oven to an internal temperature of 140 F, according to the United States Department Agriculture. Depending on personal preference, the temperature and cooking method can vary as long as the internal temperature is reached. Make certain the ham is specifically labeled as cooked or fully cooked, both are synonymous with a ham that is safe to eat without any further cooking time.
A spiral ham is always precooked and spirally cut. Since the ham is already sliced, it is best served cold as reheating will dry out the meat. If reheating a spiral ham is desired, cover the ham with heavy duty aluminum foil and heat to an internal temperature of 140 F in a conventional oven, about 10 minutes per pound. Individual slices can be heated in a skillet or microwave.
Fully cooked ham, sometimes referred to as a city-style ham, is a good option for sandwiches and salads or can be added to recipes, slow cooker dishes, grilled or reheated in the oven. In order to reheat, place in a preheated oven at no less that 325 F until it reaches an internal temperature of 140 F.
All other cook-before-eating hams like fresh or country ham should be cooked thoroughly according to package or recipe instructions in order to reach an internal temperature of 165 F.