Canker Sores vs. Cold Sores: What’s the Difference? Seattle, WA General & Family Dentist Explains
Updated: Dec 19, 2022
Cold and flu season is upon us, and unfortunately, mouth sores sometimes accompany these illnesses. Canker sores and cold sores can be quite unpleasant to live with, but the good news is that both typically heal well within a couple weeks. We’ll explain how to tell the difference between canker sores and cold sores, and how to treat them so that they heal quickly and with minimal discomfort and pain.
Symptoms and Characteristics
Cold sores and canker sores may seem similar, but they are unrelated issues with distinct and identifiable symptoms. Let’s take a look at the differences between the two:
Canker Sore (aphthous ulcer)
Cold Sore(aka fever blister, HSV-1 or oral herpes outbreak)
Inside the mouth – usually on the inside of cheeks or lips, or on the tongue.
Typically outside the mouth – on or around the lips.
Usually a small, shallow, round or oval wound. White or yellowish in color with a red border.
Initially a tingling, burning or swollen sensation on the lip; within about 24 hours a cluster of fluid-filled blisters appears on that spot. After the blisters break, they leak fluid and begin to dry out and crust over.
The exact cause of canker sores is unknown, but they may be triggered by:
Nutritional deficiencies (particularly in vitamin B-12, zinc, folic acid or iron)
Allergic or other immune reactions (to acidic foods or drinks, certain medications, mouthwash)
Dental appliances (like braces, dentures or retainers)
Injury inside the mouth
Unlike canker sores, we know what causes cold sores: a virus called herpes simplex type 1, also called HSV-1 or oral herpes (which is not the same as genital herpes, HSV-2). It is estimated that nearly 90% of Americans have HSV-1, though some people never exhibit any symptoms. Others experience periodic outbreaks, which can be triggered by:
Overexposure to sunlight or wind
Injury to areas where sores previously appeared
Surgery or dental procedures
Canker sores usually heal on their own within 1-2 weeks. Because they are essentially open wounds inside the mouth, canker sores can make talking and eating quite painful. Tips to aid healing and reduce pain:
Avoid acidic or spicy foods and abrasive foods (like chips, crackers, pretzels), which can cause further discomfort and irritation.
Get plenty of rest, eat a balanced diet and drink plenty of water.
Use a mouth rinse to help clean and dry out the wound. Home remedies include salt water, baking soda or hydrogen peroxide mouth rinses – 1 teaspoon salt or baking soda mixed with 1 cup warm water – or 1 part hydrogen peroxide mixed with 2 parts water. OTC options include mouth rinses containing hydrogen peroxide, dexamethasone, or chlorhexidine.
OTC topical anesthetics like benzocaine can help reduce pain.
OTC corticosteroid ointments like fluocinonide can provide a protective coating.
Notify your dentist or doctor if you have canker sores that are: frequently recurring, exceptionally painful, accompanied by high fever, or extend onto the lips. Your doctor can diagnose an underlying condition if any, or suggest additional treatment such as antibiotics.
Though there is no cure for HSV-1, cold sores usually heal on their own within 1-3 weeks. Tips for treating cold sores to reduce recovery time, appearance and discomfort:
At the very first warning sign – the tingling or burning sensation on the lip – dab a drying agent on the area a couple times daily to help dry up the blister. E.g.: a solution of 1 part hydrogen peroxide to 1 part water, 70% rubbing alcohol, zinc oxide, calamine lotion, or witch hazel.
Apply a topical ointment multiple times daily at first warning sign and until the sore heals completely. Popular OTC ointments containing ingredients like docosanol (Abreva), benzyl alcohol (Zilactin), zinc oxide, glycine or lysine can speed healing, reduce pain and soften scabs. Ointments containing ingredients like benzocaine, menthol, phenol and petroleum jelly can also help reduce itching, discomfort and redness.
Use a lip balm with SPF 30 or higher to prevent the cold sore from worsening.
Avoid touching or picking at the sore and scab - it can lead to further irritation, longer healing time, and scarring.
Avoid spreading the infection! Do not kiss others, and do not share cups, water bottles, eating utensils, towels, or anything else that may come in contact with your mouth or face. Wash your hands very thoroughly every time you touch your face or lips, do not touch your eyes or genitals after touching your lips, throw away any lip balms used during outbreak, and use a new toothbrush after the cold sore heals.
For severe cold sores, you may want to visit a doctor for a prescription antiviral medication. Common prescribed medications include: docosanol and penciclovir creams, acyclovir, famciclovir, and valacyclovir pills.
See a doctor if cold sores last longer than a few weeks, if you develop a high fever, or if you notice accompanying eye irritation.
The symptoms, causes and treatments for cold sores and canker sores are quite different, which makes sense since they are two entirely different conditions! But whether they are canker sores or cold sores, most people experience painful mouth sores at some point in their lives. They are usually no cause for alarm and heal well within a couple weeks. Follow our tips for reducing pain and recovery times, and visit your doctor if the sores are accompanied by high fever or other unusual developments.
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