What are cold sores?

Cold sores are small blisters on your skin, often around your lips and mouth. They are caused by a type of herpes simplex virus (HSV).

What is HSV?

HSV (herpes simplex virus) is a very common virus that is spread through direct contact with the skin, saliva or genitals of an infected person.

There is no cure for HSV. If you have HSV, it will always remain in your body, though you will not always have symptoms. From time to time your infection may be reactivated and cause symptoms such as cold sores or genital herpes sores.

There are 2 main types of herpes simplex virus (HSV): HSV-1 and HSV-2. Both types can infect any part of the body, but symptoms tend to appear in different areas.

• HSV-1 (type 1) — commonly causes cold sores on the face and lips, and occasionally on the genitals.
• HSV-2 (type 2) — commonly causes genital herpes, sores around the genitals or anus, and usually spreads during sexual contact.

What are the symptoms of HSV-1?

Most people do not have any symptoms when they first catch HSV-1 (primary infection). This means you can carry the virus without knowing you have it. Primary infection with HSV-1 can cause:

• throat infection
• dehydration
• a tingling or burning sensation in or around your mouth
• mouth ulcers
• high fever for a few days
• irritability
• muscle pain

If your infection is reactivated, you may first feel tingling and burning on or around your lips. You may then develop a cold sore at that spot. Most people do not have a fever when the infection is reactivated.

It can take up to 10 days for cold sores to heal.

What causes cold sores?

Cold sores are caused by a reactivation of the HSV-1 virus. HSV-1 can spread through:

• kissing
• oral sex
• sharing personal items, such as food or utensils

You can spread HSV-1 even if you do not have or have never had any visible sores or symptoms.

HSV-1 may be reactivated by:

• a weak immune system
• fever
• emotional or physical stress
• exposure to a lot of sunlight or wind

How is the cause of cold sores diagnosed?

Cold sores can be diagnosed by a doctor during a physical examination. They may ask you about your symptoms, medical history and examine you.

Your doctor can confirm the diagnosis by sending a swab from the cold sore to a laboratory to check for HSV-1.

When should I see my doctor?

You should see your doctor if you develop cold sores during pregnancy or if you are breastfeeding. Together you can discuss your treatment options and plan how to manage your symptoms while breastfeeding.

You should also see your doctor if you have cold sores that are not getting better despite treatment.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How are cold sores treated?

Self-care at home

If you have cold sores, you can manage your symptoms by:

• taking pain-relief medicines, such as paracetamol
• using ice cubes over the sores to help relieve pain, burning, tingling and itch
• gently dabbing a soothing cream, such as aloe vera, over your cold sore

Medicines for cold sores

If you develop cold sores during pregnancy, your doctor may prescribe an antiviral medicine such as aciclovir or valaciclovir. Depending on your symptoms and the formulation recommended by your doctor, you may take it as a cream, tablets or an intravenous infusion (IV drip).

These medicines are safe to take when you are pregnant and breastfeeding.

The antiviral medicine famciclovir is not recommended during pregnancy or breastfeeding, as there is not enough research to determine whether it is safe during this time.

Always speak to your doctor or pharmacist before taking any medicine when you are pregnant or breastfeeding.

Living with cold sores

If you have cold sores, you can safely breastfeed your baby as long as you do not have sores on your breast or nipple. If you do develop sores on your breast or nipple, you should stop breastfeeding from the affected breast until the sores have cleared up.

While you are treating the infection, you should express milk from the affected breast and throw the breast milk away.

Talk to your doctor or maternal child health nurse as soon as you notice a cold sore on your breast or nipple.

Read more about:

• how to hand express breast milk
• expressing and storing breast milk
• breast pumps

What are the complications of cold sores?

Most people do not develop complications from cold sores.

In rare cases, complications include:

• oesophagitis — swelling and irritation of the oesophagus. This is more common in people who have a lowered immune system.
• erythema multiforme — a skin reaction with red and round spots on your skin. You may develop this a few days after you get cold sores.
• encephalitis or meningitis
• eye infections
• hepatitis
• cold sores on your fingers or toes

How can cold sores affect my pregnancy?

During pregnancy, your immune system is lowered. This increases the chance of developing complications from cold sores.

If you have had cold sores before, it is common to experience a reactivation of the infection during pregnancy.

Primary infection with HSV during pregnancy may lead to miscarriage or other pregnancy complications.

How can cold sores affect my baby?

Sometimes, HSV can cause severe problems for children. They can develop infections of the eyes, throat and brain. These can be serious.

Signs that your baby may have HSV include:

• blisters on their skin
• fever
• seizures

If you think your baby might have HSV, do not wait to see if they get better — seek medical help. Let the medical staff know if you or your partner have ever been diagnosed with HSV, have a cold sore or have genital herpes.

Can cold sores be prevented?

HSV infection is common because it is so easy to spread. While nothing can completely prevent the spread of the infection, here's how you can reduce the chance of spreading it:

• Don't share utensils or towels with someone who has cold sores.
• Avoid sexual contact, especially kissing or oral sex, with someone who has a cold sore.
• Always wash your hands after touching a cold sore.

You can reduce the chance of reactivating the infection by looking after yourself:

• Try to get enough sleep.
• Reduce your stress levels — relaxation techniques can help relieve stress.
• Avoid excessive sunlight exposure.
• Apply sunscreen on your lips when you are in the sun.
• Maintain a healthy and balanced diet.
• Limit your alcohol consumption.

How can I protect my baby from HSV infection?

Here's how you can reduce the chance of your baby catching HSV:

• If you have a cold sore, cover it when you are around your baby.
• Avoid kissing your baby until your sores have completely healed.
• Always wash your hands after touching a cold sore and before touching your baby.
• Ask any relatives with cold sores to avoid touching or kissing your baby.

Resources and support

If you are worried about your baby, see a doctor or midwife, or take them to your nearest local hospital.

• Read the Royal Hospital for Women fact sheet on Cold Sores in Pregnancy and Breastfeeding.
• Learn more about herpes (HSV) on the HealthyWA website.
• Call Family Planning NSW Talkline on 1300 658 886 or visit your nearest Family Planning NSW clinic.

Languages other than English

The SA Health informative webpage about cold sores can be translated into many community languages.

Information for Aboriginal and/or Torres Strait Islander peoples

The Australian Nurse-Family Partnership Program (ANFPP) is a nurse-led home visiting program that supports Aboriginal and/or Torres Strait Islander people who are pregnant.