Cold Sore

1 What is Cold Sore?

Cold sores or fever blisters are group of small blisters filled with fluid which usually develop on and around your lips.

Once the blisters burst, the sore is covered with crust. Cold sores usually disappear within two to four weeks and leave no scar. Cold sores transmit through close contact, such as kissing.


They are caused by herpes simplex virus (HSV-1 and HSV-2). Both viruses affect your mouth and genitals. These viruses can spread by oral sex. Cold sores are communicable even if no sores are seen.

HSV infection can’t be cured and the blisters may recur. Antiviral agents help in quick healing and reduce the frequency of recurrence.  

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2 Symptoms

Cold sores show a number of symptoms. Most patients feel a tingling sensation before the sore is visible.

Cold sores develop in the following sequences:

Tingling and itching

Many people experience itching and burning around the lips few days before the appearance of group of small, painful blisters.


Those blisters filled with fluid rupture after few days. Cold sores can appear around the nose or on the cheeks.

Oozing and crusting

The group of small blisters may combine and then break out. Then a crust is developed over the sores. Signs and symptoms depends on whether this is the first outburst or reappearance.

Blisters usually heal within few weeks. Recurrences are less severe and appear almost at the same spot. Symptoms last for several days. 

If it's your first outbreak, you may also experience:

Children younger than 5 years may develop cold sores inside their mouths which can be confused with canker sores. Canker sores affect the mucous membrane only and aren't caused by the herpes simplex virus.

When to see a doctor?

Cold sores do not require treatment for healing. Visit your doctor if:

  • You have weakened immune system
  • The cold sores don't clear up within two weeks
  • There are severe symptoms
  • Cold sores reappear regularly
  • Your eyes are irritated

3 Causes

Cold sores are caused by herpes simplex virus (HSV), especially HSV-1. HSV-2 causes genital herpes. But, both can cause sores in the face or on the genitals.

Most people infected with HSV-1 may not experience signs and symptoms. Cold sores are mostly transmitted when fluids seep out from the blisters.

However, the virus can spread even if blisters are not present. HSV-1 can be transmitted by sharing utensils, razors and towels, as well as kissing.

Transmission of HSV-1 to genitals and HSV-2 to lips can occur due to oral sex. Once you're infected with herpes, the virus may become dormant and lie in nerve cells in your skin.

It may recur at the same spot. Reappearance of cold sore can be elicited by

  • Viral infection or fever
  • Hormonal changes, for example during menstrual period
  • Stress
  • Exhaustion
  • Exposure to sunlight and wind
  • Weakening immunity

4 Making a Diagnosis

Diagnosis of cold sores can be done simply by looking at them. However, confirmation requires taking a sample from the blister for laboratory analysis.

Cold sores disappear within two to four weeks without any treatments.

Visit your doctor if your cold sores:

  • Don’t heal within few weeks or are severe
  • Recur regularly
  • Cause eye irritation

How to prepare yourself for the visit?

Getting prepared for the visit can optimize the therapy and help make the visit more fruitful. List out all the symptoms.

Write down your key medical information. Write down the names of all your medications, vitamins or supplements. Ask a friend or a family member to accompany you during the visit.

Make a list of the questions to ask your doctor

Some typical questions can be:

  • Are these cold sores?
  • What are my treatment options?
  • Are there any self-care approaches that can help me?
  • Is my condition contagious? For how long?
  • What can I do to reduce the risk of spreading this condition?
  • When will my symptoms will improve?
  • Can my condition cause some complications?
  • How can I prevent a recurrence?

What your doctor wants to know

A clear talk with your doctor can optimize the therapy and improve the outcomes. Prepare yourself to answer some essential questions from your doctor.

Your doctor might ask you typical questions like:

  • Have you experienced such symptoms earlier?
  • Do you have a history of skin problems?
  • Did you experience any other symptoms before the sore became visible?
  • Are your eyes irritated?
  • Does anything trigger your symptoms?
  • Do you have a history of cold sores? If so, what were the treatments and which was most effective?
  • Have you been going through some rough times?
  • Are you pregnant?
  • Have you come into contact with infants or with people who have major illness?

5 Treatment

Cold sores usually heal within few weeks and do not need any specific treatment.

Several prescription antiviral medicines can be used for quick healing.

Antiviral agents used are

  • acyclovir,
  • valacyclovir,
  • famciclovir,
  • penciclovir.

They are available as tablets or creams.

Tablets are found to be more effective than creams.

In severe cases, antiviral agents can be injected. 

6 Prevention

To prevent cold sores, avoid contact with those who show symptoms. If you've already had cold sores, speak with your doctor about medication if they occur frequently.

You may have to take antiviral drugs regularly if your cold sores appear frequently or you are likely to have complications.

If sunlight elicits the reappearance of cold sores, use sunscreen on the spot where they develop.

To help avoid transmitting cold sores to others or any other parts of your body, you should:

  • Avoid close contact with others when you have blisters. The virus transmits mostly from the secretion of blisters
  • Avoid sharing items, such as utensils, towels, lip balm and other items, while the blisters are still present.
  • Wash your hands regularly. If you have a cold sore, make sure you wash your hands before you touch yourself or others, particularly babies.

7 Alternative and Homeopathic Remedies

Even though the results from different studies are not conclusive, following alternative remedies have been used for cold sores:


It is an amino acid and can be taken orally or applied as a cream. 


Also known as synthetic beeswax, it is available as ointment. Early and frequent application can cut down the length of outburst.

Rhubarb and sage

A cream containing rhubarb and sage can be equally effective as acyclovir.

Stress reduction

Stress triggered cold sores can be reduced by different relaxation methods, such as

8 Lifestyle and Coping

Following measures may be helpful in coping with cold sores:

Apply a cold sore ointment

Docosanol, a non-prescription cream, can be applied regularly. It may shorten the eruption by few hours or a day.

Consider using other cold sore remedies

Other over-the-counter preparations containing a drying agent, such as alcohol, can quicken the healing process.

Use lip balms and cream

Zinc oxide or lip balm with sunblock can protect your lips from the sun Applying moisturizing cream to your dried lips can be helpful.

Apply a cool compress

A cool compress can be helpful in removing crust as well as speed up healing.

Apply pain-relieving creams

Over-the-counter creams containing lidocaine or benzocaine can be used to relieve pain.

9 Risks and Complications

There are several risks and complications associated with cold sores.


Nearly 90% of adults in the world test positive with cold sore causing virus despite experiencing no symptoms of an infection.

People with compromised immune system are likely to experience complications from the virus. Following conditions are associated with higher risk of complications:

  • HIV infection
  • Severe burns
  • Other skin conditions such as eczema
  • Cancer chemotherapy
  • Immune suppressing drugs for organ transplants


In some people, cold sore can develop in other parts of bodies including:


Both HSV-1 and HSV-2 can be transmitted to the fingers. Infection in fingertips is known as herpes whitlow. If children frequently suck their thumbs, the infection may spread to the thumbs.


The virus can spread to eye and cause eye infection. Recurrent infections can cause scarring and injury to eyes, which can cause vision problems or blindness.

Widespread areas of skin

People with eczema are likely to transmit cold sores all across their bodies. This condition requires emergency medical care.

Other organs

The virus can spread to organs such as, the spinal cord and brain in people with weakened immune system.