How to Safely Treat a Cold Sore While Pregnant 

Getting a cold sore while pregnant can feel especially stressful—particularly when you’re doing everything possible to protect your baby. For many pregnant people in Arizona, cold sores are a common concern, especially given factors such as intense sun exposure, seasonal illnesses, and pregnancy-related immune changes.

Dealing with a cold sore is never easy, and we know your priority is keeping your baby safe. We’re sharing details on HSV-1 during pregnancy, how it may affect your baby, and how you can combat cold sores while maintaining a safe pregnancy.

Why Do You Get Cold Sores?

Sometimes called fever blisters, they are a cluster of small blisters on the lip and around the mouth, usually red, inflamed, and filled with liquid or pus. They are caused by the herpes simplex virus (HSV-1), which is different from HSV-2, which causes genital herpes; a common virus that many people carry and transmit via contact, not always sexual. 

According to the Centers for Disease Control, 48% of the U.S. population between the ages of 15 and 49 carries HSV-1, and many are asymptomatic.

Common Cold Sore Triggers (Especially Relevant in Arizona)

You may get cold sores periodically, depending on your stress levels and hormones, such as:

• Stress or anxiety
• Fatigue or lack of sleep
• Sun exposure (a major trigger in Arizona)
• Illness (like a cold or fever)
• Hormonal changes, including pregnancy

Can Pregnancy Trigger Cold Sores?

Yes. Pregnancy can trigger cold sores, even if you’ve gone years without one. Pregnancy alters your immune system (making colds and the flu more severe). Combined with pregnancy fatigue, stress, and environmental factors common in Phoenix, Tucson, Prescott, and surrounding areas, outbreaks may become more frequent.

To minimize outbreaks, try to control your stress, get plenty of rest, and take action to shorten the length of a cold sore at the first sign (tingling, itchy, or burning sensation on the lips).

How Long Do Cold Sores Last When You’re Pregnant?

A cold sore while pregnant typically lasts 7–14 days, similar to non-pregnant outbreaks.

Your pregnancy won’t significantly impact the duration of the cold sore cycle. If your cold sore doesn’t go away by day 10 or you have frequent outbreaks (several outbreaks in a one to two-month span), you should contact your Genesis provider.

Will Cold Sores or HSV-1 Affect My Pregnancy or Baby?

In most cases, oral cold sores do not affect pregnancy or fetal development, especially if you had HSV-1 before becoming pregnant.

If you had HSV-1 prior to pregnancy, your body has already developed antibodies that help protect your baby, making transmission very unlikely.

However, there are certain situations that require closer monitoring.

Can I Pass the Virus to My Baby?

If you contract the virus later in your pregnancy, your immune system may not have enough time to build antibodies, and you can pass the virus to your newborn. The risk of vertical transmission (transmitting the virus to your baby) is higher if you have HSV-2, especially if there are genital sores/lesions. If you are pregnant and believe you have contracted HSV-1 or -2, speak with your healthcare provider ASAP.

Neonatal Herpes: Risks and Symptoms in Newborns

If you have passed the HSV-1 or -2 to your newborn or your newborn was exposed to the virus, that is called “neonatal herpes,” and while it is rare, it can pose serious risks and complications. Neonatal herpes can affect your baby’s central nervous and respiratory systems and can even cause organ failure or death. Symptoms include:

Symptoms may include:

• Fever
• Irritability
• Skin rash or blisters
• Difficulty feeding
• Breathing problems
• Seizures
  

While rare, neonatal herpes requires urgent medical attention. The risk is highest when the birthing parent has a new HSV infection, particularly HSV-2.

How to Treat a Cold Sore While Pregnant

When treating a cold sore during pregnancy, safety always comes first. Even over-the-counter treatments should be discussed with your healthcare provider.

OTC Treatments

The most common treatment for cold sores is docosanol (brand name Abreva). It’s usually available without a prescription. However, there isn’t enough research on whether it is safe to use during pregnancy.

Antiviral use during pregnancy

Your healthcare provider may prescribe an oral antiviral medication, such as Acyclovir (also available as a cream) or Valacyclovir.

There is some evidence that taking antiviral medications during pregnancy may cause harm to the growing fetus. Oral valacyclovir is generally considered to be safe during pregnancy.

Even if you have had a cold sore before, check with your Genesis provider if you get one while pregnant, as they can counsel you on the safest treatment option.

Managing Cold Sores During Pregnancy

Unfortunately, because the HSV-1 virus and breakouts are often tied to circumstances outside of our control, it’s challenging to manage cold sores while pregnant. If you feel a cold sore coming on, you should:

• Keep the infected area(s) clean and dry, and avoid touching and picking at the blisters
• If your healthcare provider approves the use of topical creams, apply them as needed
• Wash your hands frequently

When Should I See The Doctor?

If you get a cold sore while pregnant, consult your healthcare provider, even if you have dealt with them before. Additionally, seek medical attention if:

• You experience your first cold sore during pregnancy
• Symptoms are severe or worsening
• You’re close to your delivery date
• Cold sores are not healing as expected

Your provider will not judge you; they are there to support a healthy pregnancy for you and your baby.

Compassionate Pregnancy Care in Arizona

If you’re looking for a judgment-free pregnancy care provider in Arizona, our practice proudly serves patients in Phoenix, Tucson, Prescott, and surrounding communities. Our OB-GYNs, certified nurse-midwives, and nursing staff are here to help you navigate concerns like cold sores during pregnancy with clarity and care.

If you have questions or would like personalized guidance, contact us to request an appointment today. We’re here to support you every step of the way.

Cold Sores & Pregnancy FAQ

Can I Use Cold Sore Medicine While Pregnant?

Some treatments may be appropriate with provider approval.

Can You Use Abreva While Pregnant?

Abreva (docosanol) is an over-the-counter cream, but there’s limited research on its safety during pregnancy. Many Arizona providers recommend using it only after medical consultation.

Can You Take Valacyclovir (Valtrex) While Pregnant?

Valacyclovir is commonly prescribed and generally considered safe during pregnancy when medically indicated. Large studies have not shown an increased risk of birth defects, but medication decisions should always be individualized.