How to tell cold sores from other facial and oral skin conditions

A guide to how canker sores, rosacea, impetigo and other conditions are different from cold sores


What are cold sores?

Cold sores are virus infections in the mouth area, mostly on and around the lips. They are triggered by the herpes simplex virus (HSV) and they show up as blisters that initially ooze fluid and eventually are covered by a crust and scab. After they’ve healed, there aren’t any scars left. HSV is divided into two subcategories: HSV-1 and HSV-2. The former mostly is 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 vaginal herpes risk factor just like sexual intercourse.

Studies estimate that 70-80% of people are HSV carriers, but the vast majority are silent carriers. That means they don’t experience outbreaks because they have strong autoimmune systems. That said, about 30-40% of HSV carriers will experience an outbreak of cold sores at least once in their lifetime, typically at times when the immune system is weakened, such as due to sickness, stress or chemotherapy. Only very few people are troubled with frequently recurring cold sores, though. 

Oral cold sores rarely expand to other facial areas, but if that happens you’ll need to see a doctor immediately as it could be dangerous. For example, cold sores on the eyes can lead to blindness if left untreated.

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What are the conditions similar to cold sores and how to tell them apart?

If you know that you are a 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 and 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 203 days. But below is a brief overview the most common medical skin conditions of the mouth area, which will help giving you an idea whether you have cold sores or another condition. 

Canker sores

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 by biting your tongue or scratching your lips). So, they aren’t viral infections like cold sores.

Angular Cheilitis

This disease is an inflammation of both mouth corners, which is why it’s called angular. It can be quite itchy and painful and, if not treated, last for years. The location in the corners of the mouth can make it look similar to cold sores at first. The chief difference that helps you 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, irritations such as constant lip licking, and certain food and cosmetics allergies. Once you treat the underlying cause — for example, with an anti-bacterial cream — cheilitis quickly goes away. 


This is a bacterial infection which manifests itself in 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 it 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 breakout 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 on the cheeks and nose, not so much the mouth. So, it’s quite distinct from cold sores. 

Perioral dermatitis

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 doctoring it yourself, you may use the wrong medicine, like topical steroids, which only will 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 limps. Eczema are effectively treated with steroids and other medications to manage the symptoms but in most cases can’t be healed permanently. If you have a history of eczema, you’ll know how to differentiate it from cold sores. Moreover, the eczema most likely won’t just be limited to your mouth and lips. When in doubt though, you should get your condition checked by a doctor.   


“Can Cold Sores Be Prevented?” Nih.Gov, Institute for Quality and Efficiency in Health Care (IQWiG), 12 July 2018, Accessed 11 Feb. 2020.

?lebioda, Zuzanna, et al. “Etiopathogenesis of Recurrent Aphthous Stomatitis and the Role of Immunologic Aspects: Literature Review.” Archivum Immunologiae et Therapiae Experimentalis, vol. 62, no. 3, 12 Nov. 2013, pp. 205–215,, 10.1007/s00005-013-0261-y. Accessed 11 Feb. 2020.

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,, 10.23937/2378-3656/1410205. Accessed 11 Feb. 2020.

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