How Can I Tell If It’s a Cold Sore?

Reviewed on 5/11/2022
Young man pointing at a red cold sore (fever blister, oral herpes) on his mouth
Common cold sore symptoms include painful blisters on the lips, gums, mouth, tongue, throat, or nose; blisters open and form scabs, mouth and throat pain, neck swelling, body aches, fever, and feeling ill (malaise).

A cold sore (also called oral herpes or a fever blister) is a painful blister that forms on or near the lips and inside the mouth. 

6 Cold Sore Signs & Symptoms

Symptoms of a cold sore may include: 

  • Painful blisters on the lips, gums, mouth, tongue, throat, or nose
    • Blisters open and form scabs 
  • Mouth and throat pain
  • Neck swelling 
  • Body aches
  • Fever
  • Feeling ill (malaise)

Some people may feel pain, burning, tingling, or itching on the lips about a day before cold sores erupt. 

6 Conditions That Look Like Cold Sores

Other conditions that can resemble cold sores, but are not, include: 

  • Canker sores
    • Painful red or white sores that only develop inside the mouth
    • Do not usually blister or form scabs
  • Angular cheilitis 
    • Begins as a patch of dry, irritated or cracked skin at one or both corners of the mouth
    • If not treated promptly, it may progress into swollen, painful sores that may bleed when you open your mouth
  • Pimples
    • Caused by clogged pores or hair follicles blocked by oil and dead skin cells
    • Do not look like blisters 
    • Do not form inside the mouth
  • Cracked, chapped lips
    • Caused by exposure to sunlight, cold and dry weather, or hours or days of repeatedly licking the lips 
    • Symptoms include dryness, flaking, and cracks on the entire surface of the top and bottom lips
    • They don't ooze clear fluid unless severely infected
  • Gingivostomatitis 
    • A viral or bacterial mouth infection that causes blister-like sores to form on the gums and inside the lips
    • Symptoms include tender sores on the gums or on the inside of the cheeks, bad breath, fever, bleeding gums, and swollen lymph nodes
  • Folate deficiency
    • Can cause blistering sores to form around the mouth
    • Ulcers tend to occur around the gums, inner lining of the cheeks and back of the lips (buccal mucosa), and tongue
    • Symptoms also include fatigue and weakness 

What Causes a Cold Sore?

  • A cold sore is usually caused by the herpes simplex virus type 1 (HSV-1), transmitted from person to person through kissing, sharing eating utensils, or other types of close contact.
  • People who give oral sex to others who have genital herpes can also get cold sores on their mouth. 
  • The herpes virus spreads more easily when a cold sore is present, but the virus can also be transmitted when a person has no symptoms. 

How Can I Get Rid of or Prevent Cold Sores?

There is no cure for herpes, the virus that causes cold sores, but most symptoms usually occur during the first few years following infection. After that, the virus that causes cold sores causes mild to no symptoms. 

When the virus is active, medications are used to help reduce and prevent symptoms.

People usually need treatment the first time cold sore symptoms occur. Those who have previously had cold sores or people who have mild symptoms may not need treatment.

Treatment for a cold sore may include:

  • Antiviral medications
  • Antiviral topical ointments
    • Acyclovir (Zovirax ointment or cream)
    • Penciclovir (Denavir topical)
  • Pain-relieving pills and gels that go on the mouth, some of which may be available over-the-counter (OTC)
  • Home remedies 
    • Suck on ice or popsicles
    • Eat cool, soft foods
    • Wash hands with soap and water before and after applying cream and dab the cream on lightly – do not rub it into the sore
    • Avoid known cold sore triggers
    • Use lip balm with SPF 15 or above
    • Over-the-counter (OTC) pain relievers can ease pain and swelling
    • Ibuprofen (Advil, Motrin)
    • Acetaminophen (Tylenol)
    • Do not give aspirin to children under 18 due to the risk of a serious illness called Reye’s syndrome
  • When you have a cold sore, avoid: 
    • Kissing 
    • Oral sex
    • Touching the cold sore, aside from applying cream
    • Sharing eating utensils
    • Eating salty or acidic food if it aggravates the sore
Reviewed on 5/11/2022
Image Source: iStock Images