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Cold Sore: Symptoms and Treatments

How to know if the blister on your lip is a cold sore.
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Medically reviewed by
Clinical Instructor , Mount Sinai Hospital, Department of Dermatology
Last updated January 5, 2021

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What is a cold sore?

Cold sores, also known as fever blisters or oral herpes, are small blisters that occur in or around your lips, or on your chin or nose. They are typically filled with clear fluid. Usually, a cold sore is made up of a few little blisters that are very close together and appear more like one big blister.

They are caused by the virus, herpes simplex virus type 1 (HSV-1), that is extremely common and very contagious. It is different from genital herpes, a sexually transmitted disease (STD) that is mostly caused by herpes simplex virus type 2 (HSV-2).

You can get a cold sore at any age, but they’re most common in children and young adults. Also, having one cold sore means you have the virus for life. It can be triggered at any time, meaning that the cold sore can come back again and again.

Cold sores usually go away on their own in about 2 to 4 weeks. But medications can help them heal faster or make your symptoms easier to deal with.

Most common symptoms

Pro Tip

Cold sores are recurrent, meaning that once you have one there is a good chance that another one will occur during stressful situations or a viral illness. They often occur in the exact same location. —Dr. Lauren Levy

Usually you feel a cold sore coming on before you can actually see it. The skin around your mouth will itch, burn, or tingle. Then, usually a day or so later, a blister will come up in that spot.

The skin around the blister will become red, swollen, and painful. After a few days, the blister will burst. Fluid—usually clear or yellow—will ooze or spill out. After the blister bursts, there will be an open wound, which will scab over in a few days.

Usually, cold sores only hurt for a few days.

Most people get cold sores more than once, and they tend to arise when you are sick with a cold, have a fever, are under stress, or exposed to sunlight. Often, a cold sore will come back in the same place but the symptoms are not usually as bad as they were the first time.

Main symptoms

  • Tingling, itching, or burning before a blister comes out.
  • Small fluid-filled, painful blisters with surrounding redness on or around your lips, nose, or chin.

Other symptoms you may have

  • Fever
  • Sore throat
  • Muscle aches
  • Swollen lymph nodes (glands in your neck or under your chin)
  • Pain in your tongue
  • Pain in your gums or inside your mouth
  • Trouble swallowing
  • Headaches

What can trigger a cold sore?

Dr. Rx

If you have eczema or dermatitis, you may be prone to more cold sores or herpes outbreaks because of the open skin from your eczema. Make sure you are treating your eczema to keep the skin integrity—this can help prevent cold sores that occur on the skin around the mouth. —Dr. Levy

The herpes HSV-1 virus spreads through contact with people who are already infected with the virus. You can get the virus if you share drinks, food, utensils, or makeup with someone who has it.

You can also get it from kissing someone who has the virus. A person may have the virus without having apparent blisters on their face, but cold sores are contagious even if you cannot see them.

Various triggers can cause a repeat cold sore, including:

  • Having a cold or flu
  • Conditions or events that can weaken your immune system (cancer, chemotherapy, or certain medications that suppress your immune system)
  • Exposure to sunlight
  • Extreme heat or cold
  • Emotional or physical stress
  • Hormonal fluctuations in women during their period or pregnancy

How do you get rid of a cold sore fast?

You can use over-the-counter (OTC) creams and ointments applied directly to the sores to help decrease the discomfort and stop the virus from spreading. The most popular OTC treatment, Abreva, prevents the virus from entering the cells in your body and causing infection. Some OTC medicines contain numbing agents like menthol that reduce the pain of the cold sore.

Also, putting a cold compress on the blister can help with the pain. You can also take OTC pain relievers like ibuprofen (Advil, Motrin), acetaminophen (Tylenol), or naproxen (Aleve) to relieve pain. You should also apply a bland greasy ointment to the cold sore when it becomes dry and cracked to help with healing—Vaseline or Aquaphor work well.

If you get frequent or long-lasting cold sores, your doctor may prescribe an antiviral medication to speed up the healing process. Options include acyclovir (Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir). Rarely, a doctor will recommend an antiviral medicine given intravenously (IV), through a needle.

Preventative tips

Pro Tip

Cold sores can come out with heavy sun exposure (UV light). Wearing sun protective clothing (like a hat) and SPF on the lips can help reduce frequency of cold sores when in the sun. —Dr. Levy

Avoid sharing food, drinks, and personal items such as makeup and hygiene products with other individuals as they may have the contagious virus. Wash your hands frequently before you touch your lips or your mouth.

If you have had cold sores in the past, reduce the risk factors that make it more likely to return. For example, avoid extreme weather conditions, try to reduce the stressors in your life, get enough sleep, and ensure that you rest if you are sick with another illness.

If you have very frequent cold sores, your doctor may prescribe an antiviral medication (valacyclovir) to take daily to prevent cold sores from coming out. The vitamin, Lysine, can also be taken to reduce the frequency of cold sores.

Share your story

Dr. Dasani is a resident physician at Penn and Brigham and Women's Hospitals. She graduated from Columbia University in 2013 with a BA in Neuroscience and Behavior. Upon graduation, she served as a Fulbright scholar on the island, Bangka, Indonesia. After her Fulbright, she pursued a MD/MBA at Penn during which she worked on various health care consulting projects solving problems across multiple sectors of the health care system. She is currently a medicine resident physician at Penn and is planning to continue her anesthesia training at Harvard starting in July 2020. She is primarily interested in increasing the efficiency of health systems delivery with attention to patient safety, specifically within the perioperative realm.

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