Lahore abounds with excellent street food, but unless you've been on the road for some time and developed an iron stomach, it's always wise to exercise some caution. Look for busier street stalls, especially those in Gowal Mandi food street, and stick to food that's hot and has just been cooked. Salads can also cause problems - if you must, one of the fancier restaurants in Gulberg is probably a safer bet than eating a salad at a dhaba or street stall.
Bottled water is highly recommended. Some budget places offer free filtered water, but even that is suspect in Lahore.
Medical care is excellent for those who can afford it and, if you can, avoid public hospitals. The Fatima Memorial Hospital is usually a fair bet, with decent rates, good hygiene, and good care.
Doctors hospital on Canal and National Hospital in Defence Housing Authority offers excellent services but at a higher cost.
talk
The most common languages are Punjabi and Urdu. For the use of English there is a big diversity between different areas of Lahore. Education is generally high in Lahore and a great many of residents understand and speak a form of English. You will not have any problem communicating in English in Lahore, especially if you are visiting the old city, The Fort, The Food Street or any surrounding area including The Mall Road.
To learn Urdu or Punjabi see the entry in the Learn section below.