First, you want to determine if it is actually a pimple or a cold sore. A cold sore is caused by the herpes simplex virus type 1 (HSV-1), is contagious, and will generally go away without treatment in about 2-4 weeks. While a pimple may be tender and painful to the touch, a cold sore may itch, burn or tingle in addition to being painful. Applying ice or a cold compress can help with the discomfort of a pimple or cold sore. For a cold sore, you can use an OTC cream with lidocaine or benzocaine for pain relief. You may want to see a doctor, who may prescribe a prescription oral antiviral cream to speed up the healing process. In either case, avoid picking or squeezing the lesion. This is particularly important for a cold sore, since this can spread the virus.