Both cold sores and pimples can be bothersome, because they often hurt and may be obvious to others. While both can be irritating, they usually look and feel different, so their similarities often stop there. To tell the difference between a cold sore and a pimple, you should consider the location of the lesion; cold sores usually only show up near the mouth, but pimples can appear anywhere. The two usually look quite different as well, because cold sores often form a yellow crust. Additionally, the symptoms of a cold sore often give away its identity, because they can be felt before it even appears.
Recognizing a cold sore often requires considering the location, because sores usually show up on or around the mouth. Pimples, on the other hand, can appear anywhere on the face — or body, for that matter — though not directly on the lips. If the lesion is on your forehead, upper cheeks or nose, it is likely a pimple; it is likely a cold sore if it is on your lips. It may be more difficult to tell the difference if the blemish is near your mouth, including on your chin or lower cheeks, because both can appear in such areas.
Examine the appearance of the blemish and how it changes over time. Cold sores often release fluid and then crust over on their own, resulting in a yellow, flaky layer over the blemish. Pimples may release fluid, such as pus or blood, but usually only when you squeeze or poke them. If you have poked and prodded your blemish, causing fluid to come out, you may need to use another method to tell whether it is a pimple or a cold sore.
Pay attention to the other symptoms that accompany the blemish. If you did not notice any symptoms before the lesion appeared, then you probably have a pimple, because the only symptom that typically accompanies acne is irritation after it becomes visible. An area that feels itchy or tingly before the lesion appears often indicates a cold sore. Other symptoms of a cold sore include burning in the area before the lesion shows up and pain during the outbreak. If you are still not sure of the differences between a cold sore and a pimple, you can see a dermatologist or other medical professional to get the blemish checked out.