How Do You Get a Cold Sore on Your Lip?

Medically Reviewed on 5/25/2022

What causes cold sores?

Cold sores, also called fever blisters or oral herpes, are a viral infection that leaves small blisters around your mouth. You get a cold sore on your lip due to viral infection from herpes simplex virus type 1 (HSV-1).
Cold sores, also called fever blisters or oral herpes, are a viral infection that leaves small blisters around your mouth. You get a cold sore on your lip due to viral infection from herpes simplex virus type 1 (HSV-1).

Do you feel a tingling, itching, or burning around your mouth? If that tingly feeling turns into small blisters, you probably have a cold sore. Cold sores, also called fever blisters or oral herpes, are a viral infection that leaves small blisters around your mouth. When the blisters break, they can leave a crusty scab. Cold sores can hurt, but they usually clear up in a few weeks. Read on to learn what you need to know about cold sores.

Cold sores are caused by a viral infection from herpes simplex virus type 1 (HSV-1). Most people with HSV-1 were infected in childhood by exposure to an infected person's saliva through kisses or close contact. Sharing items such as utensils, straws, or towels with an infected person can infect you with HSV-1.

HSV-1 is extremely common. Approximately 67% of the global population carries the virus. Not everyone infected is symptomatic, so you can have HSV-1 and not get cold sores. Different conditions can trigger a cold sore outbreak, such as:

  • Temperature extremes: working outdoors in the hot sun or being exposed to cold winter winds
  • Illness such as a cold or a fever
  • Hormone fluctuations: like those associated with menstruation or menopause
  • Another infection
  • Stress 

If you get cold sores, you can transmit HSV-1 to other people. You're most likely to transmit the virus when sores are present, so if you have an active cold sore, you should avoid skin contact with other people and refrain from sharing personal items. Try not to touch your face when you have a cold sore, and wash your hands frequently to limit the spread of the virus. 

What are the symptoms of cold sores?

Cold sore symptoms are generally mild, but some people can have flu-like symptoms such as fever and muscle aches the first time they experience an outbreak. Symptoms include:

  • tingling, burning, or itching around your mouth
  • pain and swelling around the mouth
  • blisters that scab over

Cold sores most frequently appear around the mouth, but they can also appear inside of the mouth, on the fingers, or rarely on the eyes. A cold sore outbreak in your eyes can cause more severe complications, and you should contact your doctor or another health professional as soon as possible.

How are cold sores treated?

Some over-the-counter medications can prevent a cold sore from forming if you use them before you develop blisters. If you already have an active outbreak, you may want to use home remedies like an ice pack or over-the-counter pain medication such as ibuprofen to relieve any discomfort. If you're in a lot of pain, your doctor may recommend topical pain relief, like lidocaine.   

If your cold sores don't clear up or your outbreak is severe, ask your doctor about prescription anti-viral creams or pills that may help. In extreme cases, your doctor may recommend an intravenous (IV) antiviral drug, which requires medical monitoring.

Are cold sores dangerous?

Cold sores aren't usually dangerous, but a few situations can lead to more severe complications.

Genital Herpes

While HSV-1 typically only causes cold sores, it can also cause genital herpes. If you have a cold sore, you should refrain from giving anyone oral sex until your outbreak is completely healed to prevent genital infection. Genital herpes outbreaks from HSV-1 are typically infrequent, but you should avoid having sex if you have an active outbreak in your genital area.

Neonatal Herpes

If a young infant is infected with HSV-1, it can be dangerous. Babies are most commonly infected through kisses by a person with a cold sore but can also be infected by a mother with an HSV-1 outbreak in the genital area during birth. You should tell your doctor right away if you have any symptoms of genital herpes during your pregnancy, especially if you've never had an outbreak before. Avoid kissing babies if you have a cold sore. Babies under one month old are most vulnerable to neonatal herpes. While the infection is generally treatable with IV antiviral drugs, it can be fatal.

Ocular Herpes

HSV-1 can spread to your eyes if you touch a cold sore and then touch or rub your eyes. Ocular herpes causes red eye, pain, swelling, sensitivity to light, and blurred vision. If you have any symptoms of ocular herpes during or after a cold sore outbreak, contact your doctor. Ocular herpes is treatable but can lead to severe complications like scarring, glaucoma, and vision loss if left untreated. 

While cold sores can be a nuisance, they're widespread and generally nothing to worry about. Most people adapt to life with cold sores just fine, and an outbreak that needs professional medical intervention isn't typical. You can avoid spreading the virus by avoiding close contact with others when you have an active outbreak, keeping your hands away from your face, and washing your hands frequently. Remember not to share food, drinks, or personal items while you have a cold sore. If your cold sore seems excessively painful, isn't clearing up on its own, your outbreak seems severe, or you have any other concerns, you should contact your doctor for advice.

Medically Reviewed on 5/25/2022

American Academy of Dermatology Association: "COLD SORES: DIAGNOSIS AND TREATMENT."

Centers for Disease Control: "Genital Herpes – CDC Fact Sheet."

Cleveland Clinic: "Cold Sores."

KidsHealth: "Cold Sores (HSV-1)."

Mayo Clinic: "Cold Sore."

National Health Services: "Herpes simplex eye infections.", "Neonatal herpes (herpes in a baby)."

Saint Luke's: "Understanding Cold Sores."

World Health Organization: "Herpes simplex virus."