An individual cold sore will last 1–2 weeks before it heals. However, while the cold sore may disappear, the virus that causes cold sores will remain in the body.

Cold sores are small blisters caused by the herpes simplex virus (HSV). According to the World Health Organization (WHO), around 67% of the world’s population under 50 have HSV-1, which is the most common cause of cold sores. Not everyone who carries HSV knows they have it because only 20–40% of people with the virus develop cold sores.

Although HSV-1 is the most common cause of cold sores, HSV-2, which causes genital herpes, may also cause cold sores.

In this article, we look at what cold sores are, how long they last, the stages of a cold sore, treatments, and home remedies.

Cold sores, also known as oral herpes, are small, painful blisters that develop around the mouth.

A cold sore may feel:

  • tender
  • tingly
  • painful
  • swollen

Sometimes, people who develop cold sores will also develop a fever, which is why some people call cold sores “fever blisters.”

A cold sore is not the same as a canker sore. A canker sore is a small, painful bump that always occurs inside the mouth and is not contagious.

It takes 1–2 weeks for cold sores to heal completely. However, according to Harvard Health Publishing, the virus that causes cold sores remains in the person’s body throughout their life.

HSV may lie dormant for years and cause no symptoms. In some people, the virus will reactivate and cause cold sores. Between 5–10% who get cold sores get them as frequently as five times a year.

Many people contract HSV as children and carry the virus throughout their life.

Cold sores develop and heal in the following stages:

  • Stage 1: Itching, tingling, or burning sensations mark the prodrome, or formation stage. The affected area may swell.
  • Stage 2: Within around 2 days of the first symptoms, small, fluid-filled blisters form on the face, most often on one side of the lips. People getting cold sores for the first time, such as young children, may also develop a fever or a sore mouth.
  • Stage 3: At this stage, the blister bursts, and the area may be painful. This will last around 3 days and is when cold sores are most contagious.
  • Stage 4: This is the scabbing phase when scabs form but may crack, bleed, burn, and itch. This phase typically lasts for 2 or 3 days.
  • Stage 5: In the final phase, the cold sore heals completely, and the scab falls off.

Cold sores are contagious before they are visible through to when they have completely healed. Cold sores are most contagious in the third stage when the blisters break open and start releasing fluid.

There are no treatments that can cure cold sores outright. Instead, a person can try treatments that reduce symptoms, the frequency of cold sores, and speed healing.

The following over-the-counter (OTC) treatments may help with swelling, soreness, and discomfort:

  • topical cold sore creams
  • patches to protect the sore
  • numbing creams
  • OTC medication to reduce swelling, such as ibuprofen

For severe cases, a doctor may prescribe antiviral medication. A person should start using prescription treatments within 24 hours after symptoms appear.

Prescription medications used to treat cold sores include penciclovir, valacyclovir, famciclovir, and acyclovir.

If you are pregnant, antiviral medication may still be used if there is a high concern that the herpes virus could be transmitted to the baby.

In general, women with herpes can breastfeed unless they have an active lesion on their breast. Oral acyclovir is also considered safe for women who are breastfeeding.

Topical antivirals applied to the breast should only consist of creams or gels, as ointments can pose a risk to the infant due to mineral paraffin contents.

When children have problems with painful, recurring cold sores, pediatric dentists may use lasers to help stop the pain.

Although it is common for cold sores to reappear in the same spots over time, a 2011 report on the use of lasers indicated that cold sores do not reappear in laser-treated areas.

Home remedies and self-care can help people feel more comfortable as a cold sore heals. A person can try:

  • applying ice
  • staying hydrated
  • avoiding very salty or acidic foods and beverages
  • keeping the lips moist with creams or lip balm

HSV can reactivate when a person is stressed, anxious, tired, sunburned, or experiencing hormonal changes. As such, it may help a person with reoccurring cold sores to:

  • get adequate sleep
  • try relaxation techniques
  • seek treatment for anxiety, if needed
  • protect the skin and lips from the sun using SPF
  • avoid using tanning beds

Some people use complementary therapies to help cold sores heal, including:

  • cold teabag compresses
  • lemon mint salve
  • diluted tea tree, geranium, or lavender essential oil

While some essential oils do display some antiviral properties, researchers have not confirmed if they can speed up cold sore healing. Additionally, a person should be careful applying essential oils near the mouth, as some are toxic if ingested.

A person with an active cold sore should try to avoid touching it. The following practices can help prevent the spread of HSV:

  • avoiding kissing anyone
  • not sharing towels, dishes, or cutlery
  • washing the hands after touching a cold sore
  • applying ointments to the cold sore with a cotton swab
  • avoiding physical contact sports
  • disposing of products that have directly touched the sore
  • avoiding oral sex

Although research suggests essential oils may have some health benefits, it is important to remember that the Food and Drug Administration (FDA) does not monitor or regulate the purity or quality of these oils. A person should talk with a healthcare professional before using essential oils and research the quality of a particular brand’s products. It is also important to always do a patch test before trying a new essential oil.

Cold sores are a very common symptom caused by HSV. A cold sore will last 1–2 weeks and go through five distinct stages before healing.

Cold sores may return throughout an individual’s life, although they can become less severe over time. In most cases, home care and OTC remedies can relieve symptoms and speed healing. Prescription antiviral medications and laser treatment can also help.