Cold sores are the result of a viral infection, and occur mostly around the mouth or on the lips. They initially present as blisters that may ooze fluid and are eventually covered by a crust or scab. Eventually they heal without scarring. The culprit in the infection is herpes simplex virus (HSV). HSV is divided into two subcategories: HSV-1 and HSV-2. The former is mostly responsible for oral herpes, i.e., cold sores, while the latter type tends to be more common with genital herpes. But, in principle, both types can cause either oral or genital herpes. Hence, oral sex is a risk factor for contracting genital herpes, just like sexual intercourse.
Studies estimate that 70-80% of the adult population are HSV carriers, but the vast majority are silent carriers. That means they don’t experience outbreaks because they have an intact immune systems. That said, about 30-40% of HSV carriers will experience an outbreak of cold sores at least once in their lifetime. This typically occurs due to UV light exposure or at times when the immune system is weakened, such as during an illness, during times of heightened stress or when receiving chemotherapy. Very few people will experience frequently recurring cold sores, however.
Typical cold sores rarely involve other facial areas If this does happen you’ll need to seek immediate medical attention, as this can be a serious condition. For example, cold sores on the eyes can lead to blindness if left untreated.
If you know that you are an HSV carrier and if you already experienced a cold sore outbreak before, you most likely know what you are dealing with when there’s a new outbreak. However, if you never had cold sores in the past but notice some unusual skin problems around the mouth or on the lips, it could be cold sores but also a variety of other skin conditions. Only a doctor can give you an accurate diagnosis, which is why you should seek medical help if the skin problem persists for longer than 2-3 days.
Below is a brief overview the most common skin conditions involving the mouth area, which will help give you an idea as to whether you have cold sores or another condition.
Canker sores are relatively easy to tell apart from cold sores, because they are located inside the mouth (sometimes on the tongue and gums) and don’t appear on the outside or around the lips. Canker sores are yellowish in color and painful. They are believed to be caused by stress or physical damage (such as biting your tongue). They are not viral infections like cold sores.
This condition is an inflammation of both corners of the mouth, which is why it’s called angular. It can be quite itchy and painful and, if not treated, can last for years. The location at the corners of the mouth can make it look similar to cold sores at first. The chief difference that helps in telling them apart is that cold sores form groups of small blisters, whereas angular cheilitis appears as a patch of dry, irritated red skin. Causes of angular cheilitis can be bacterial (not viral) infections, irritation such as constant lip licking, and certain food and cosmetics sensitivities. Once you treat the underlying cause — for example, with an anti-bacterial cream — cheilitis quickly goes away.
This is a bacterial infection which manifests as itchy blisters which seep fluid when they break and then are covered by yellowish crusts. An impetigo outbreak can appear anywhere on the face, limbs, and (less commonly) other body parts, and requires antibiotics treatment. If you suffer from impetigo, the blisters most likely won’t just be limited to your mouth and lips, which makes it easy to tell apart from cold sores. One word of caution: in rare cases impetigo can occur on top of cold sores. Which is why it makes good sense to always have a cold sore outbreak checked by a physician.
Rosacea is a long-term condition where patches of facial skin turn reddish and develop small bumps, sometimes accompanied by fluid-filled blisters. These “flare ups” can last for days, weeks or months. There’s no permanent cure, but medication can control the flare ups. Rosacea mostly shows up on the cheeks and around the nose, not so much on the mouth. It is quite distinct from cold sores in this manner.
This skin condition is a red, bumpy facial rash that normally appears above and below your mouth but not on the lips. Sometimes it’s difficult to tell apart from acne, rosacea or eczema, which is why you’ll need a diagnosis from a dermatologist. This is also important because if you try treating it yourself, you may use the wrong medicine, like topical steroids, which can worsen the condition.
Eczema is a fairly common skin condition (~30% of Americans have some form of it), where patches of skin turn itchy, cracked and red. It can happen anywhere on the body, but most often is seen on the face, head and extremities. Eczema is effectively treated with steroids and other medications to manage symptoms but in most cases can’t be cured permanently. If you have a history of eczema, you’ll know how to differentiate it from cold sores. Moreover, eczema is not likely to be limited to your mouth and lips. When in doubt have your skin condition checked by a doctor in person.
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Lior, Zusmanovich, et al. “Current Microbiological, Clinical and Therapeutic Aspects of Impetigo.” Clinical Medical Reviews and Case Reports, vol. 5, no. 2, 30 Apr. 2018, clinmedjournals.org/articles/cmrcr/clinical-medical-reviews-and-case-reports-cmrcr-5-205.pdf, 10.23937/2378-3656/1410205. Accessed 11 Feb. 2020.