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Cold sores in pregnancy

8-minute read

Key facts

  • Cold sores are caused by herpes simplex virus (HSV).
  • HSV is very common and is spread from one person to another by contact of the skin, saliva, or genitals.
  • There are 2 types of HSV, type 1 causes mostly cold sores on the face, and type 2 causes mostly genital herpes.
  • Genital herpes can be passed to your baby during childbirth.
  • HSV in babies can cause eye or throat infections, damage to the central nervous system, and rarely, even death.

What are cold sores?

Cold sores are small blisters on the skin, often around the mouth. They are caused by herpes simplex virus (HSV).

What is HSV?

The herpes simplex virus (HSV) 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, so once you have the virus, it will stay in your body for life.

What are the symptoms of HSV?

HSV does not always cause symptoms, so you can carry it without knowing it.

There are two main types of HSV:

  • HSV-1 (type 1) commonly causes cold sores on the face and lips, and sometimes on the genitals. Around 4 in every 5 Australian adults have this type.
  • HSV-2 (type 2) causes mostly genital herpes — sores around the genitals or anus, and usually spreads during sexual contact. Around 1 in 8 sexually active Australians has genital herpes.

Will cold sores or genital herpes affect my pregnancy?

If you have had cold sores before, it is quite common to have an outbreak during pregnancy, even if you haven't had one for a long time. If you are infected with HSV for the first time early in your pregnancy, it may lead to miscarriage.

Cold sores do not usually affect your unborn baby, but they are uncomfortable and infectious. While you're pregnant, or if have a health condition that affects how your immune system works, HSV can cause severe illness.

If you have genital herpes, the virus may transfer to your baby during a vaginal birth. If it is your first outbreak, your baby may be more at risk. This is because your body hasn't had time to develop immune protection against the virus, which also helps protect your baby.

If you have a genital herpes blister when you give birth, or if your first infection occurs within the last 6 weeks of pregnancy, your doctor may recommend a caesarean. This can help prevent the herpes virus passing from you to your baby during a vaginal birth.

When should I see my doctor?

If you have HSV and you become pregnant, or if you develop cold sores or genital herpes during pregnancy, it's important to speak with your doctor or midwife, and discuss your treatment options. Together, you can plan how to manage your symptoms during pregnancy.

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How are cold sores treated during pregnancy or breastfeeding?

You can treat cold sores with aciclovir cream — an antiviral cream that you can buy from a pharmacist without a prescription. You apply this to cold sores directly. Ask your pharmacist for advice on how to apply this cream.

If your symptoms are painful, your doctor can prescribe aciclovir or valaciclovir tablets. These antiviral medicines are thought to be safe during pregnancy and breastfeeding. Famciclovir tablets are not recommended during pregnancy.

Always speak to your doctor before taking any medication when you are pregnant.

How do I protect my baby from herpes?

A newborn baby can be infected with HSV from a kiss or a touch from someone with cold sores, or during vaginal birth (if you have a genital sore at the time your baby is born).

The risk of you spreading genital herpes to your baby during pregnancy is low, and most babies born to mothers who carry the virus are not affected. Sometimes, HSV can cause serious problems for a baby, such as infections to the eyes and throat, damage to the nerves, and in rare cases, death. Talk to your doctor or midwife about the best course of action for your situation.

If you or your partner has a cold sore or genital herpes, ask your doctor how you can best manage it during the pregnancy and after the birth. This will lower the risk of passing the virus to your baby.

It's important to maintain strict hygiene habits when caring for a new baby. If you, or anyone in close contact with the baby has cold sores, help prevent spreading the virus by:

  • covering cold sores when you are around your baby
  • avoiding kissing your baby until the sores have completely healed
  • avoiding touching the cold sores with your hands
  • washing your hands thoroughly before touching your baby
  • asking any relatives with cold sores to avoid touching or kissing your baby

What if I have a cold sore while breastfeeding?

If you have cold sores, it is safe to breastfeed your baby as long as the sores are not on the breast or nipple. If they are, you should temporarily stop breastfeeding from the affected breast until the sores have cleared up.

You should express and dispose of breastmilk from the affected breast. Breastmilk can be contaminated if it comes in contact with the skin lesions. Talk to your doctor or midwife as soon as you notice a cold sore on your breast or nipple.

Complications of HSV and what happens if my baby gets a cold sore?

If you think your baby is developing a cold sore, show your doctor or midwife as soon as you can. Signs of HSV infection include:

  • blisters on the skin
  • fever
  • seizures
  • tiredness
  • poor feeding

These signs also happen in many other health conditions, but if you think your baby might have HSV, don't 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 genital herpes.

Resources and support

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

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: June 2023


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Need more information?

Genital Herpes (HSV) | Body Talk

Genital herpes is a common STI caused by the Herpes Simplex Virus (HSV). Find out all the facts about Genital Herpes here.

Read more on Body Talk website

Cold sores - Better Health Channel

Cold sores are blisters around the mouth and nose, caused by the herpes simplex virus.

Read more on Better Health Channel website

Cold sores | SA Health

Herpes simplex virus type 1 (HSV1) causes cold sores on the face or lips - it is spread by skin or mucous membrane contact with infected saliva

Read more on SA Health website

Cold sores: children & teens | Raising Children Network

Cold sores are quite common in older children and teenagers. Cold sores usually clear up by themselves, but see your GP if you’re concerned.

Read more on raisingchildren.net.au website

Herpes (HSV)

Genital herpes is a sexually transmitted infection (STI) which shows as blisters or sores on the genitals. This is caused by the herpes simplex virus (HSV).

Read more on WA Health website

Genital Herpes | Family Planning NSW

Genital herpes is a common sexually transmitted infection (STI) caused by the herpes simplex virus (HSV). There are two types of herpes simplex virus.

Read more on Family Planning Australia website

Genital herpes and pregnancy | Health and wellbeing | Queensland Government

If you are pregnant and you get genital herpes, it is important to tell your midwife or obstetrician.

Read more on Queensland Health website

Genital Herpes - Symptoms, treatment & advice - Sexual Health Victoria

Genital herpes is one of the most common sexually transmissible infections. Very effective treatment is available from your doctor or sexual health clinic.

Read more on Sexual Health Victoria website

Herpes simplex mouth infection in children | Raising Children Network

A child with a herpes simplex mouth infection might have a sore mouth, mouth ulcers and trouble eating and drinking. It’s a good idea to see a GP.

Read more on raisingchildren.net.au website

Roseola infantum: babies and children | Raising Children Network

Roseola infantum is a viral infection in babies and children. Symptoms include fever and rash. It mostly clears by itself, but see a GP if you’re worried.

Read more on raisingchildren.net.au website

Call us and speak to a Maternal Child Health Nurse for personal advice and guidance.

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