Aciclovir tablets can be prescribed during pregnancy when clinically appropriate, including for some first episodes or severe or frequent outbreaks. For a straightforward cold sore, aciclovir cream may be preferred because very little of the medicine is absorbed into the bloodstream.
Most pages on this subject answer the tablet question and stop there. That leaves out two things people often want to know: whether the cold sore cream in the bathroom cupboard is suitable during pregnancy, and whether any of this matters once the baby is here and feeding.
Cold sores are common, and some people may have more frequent outbreaks during pregnancy. If you are pregnant or breastfeeding, it is understandable to want clear advice about treating a cold sore while keeping your baby protected.
This page looks at aciclovir cream and tablets separately, explains why aciclovir may be preferred over valaciclovir in some situations, covers what is known about breastfeeding, and looks at ways to manage a painful cold sore during pregnancy. It also covers pain relief, precautions around newborns and when to seek medical advice.
Key Things to Know
- Topical treatment involves very little absorption into the bloodstream, which is one reason it may be preferred for a straightforward cold sore
- The small packs of cold sore cream sold from pharmacies are pharmacy medicines, so a pharmacist can advise you before you buy one
- Aciclovir is generally considered compatible with breastfeeding and is commonly used when antiviral treatment is needed
- Paracetamol is generally considered the first choice for pain relief during pregnancy. Anti inflammatory painkillers such as ibuprofen are generally avoided unless a healthcare professional advises otherwise
- Anything that could be a first genital herpes episode during pregnancy needs assessment by your maternity team rather than relying on a website alone
Can Pregnant Women Use Cold Sore Cream?
In many cases, yes. Aciclovir cream may be suitable during pregnancy and is often considered for a straightforward cold sore on the lip.
If you are pregnant, it is still sensible to check with a pharmacist or healthcare professional before using a medicine, particularly if you are unsure which product to choose.
Why Cream Is Often the First Choice
Aciclovir cream is applied to the surface of the lip and only small amounts are absorbed into the bloodstream. This means that exposure to the pregnancy is expected to be low compared with taking the medicine as a tablet.
This does not mean that tablets are unsafe. The available human pregnancy data on oral aciclovir are generally reassuring. If a topical treatment is appropriate for the cold sore, there may simply be no need for oral treatment.
What the Pack Itself Tells You
The small tubes of aciclovir cold sore cream sold from a pharmacy are pharmacy medicines rather than general sale medicines. This means a pharmacist can ask about your symptoms and circumstances before selling the product.
The packaging and patient information leaflet may advise people who are pregnant or breastfeeding to speak to a healthcare professional before use. This does not automatically mean that the medicine is considered harmful. It is a reason to check that the particular product is suitable for you.
If you are unsure, a pharmacist can usually help you decide whether the cream is appropriate and how to use it.
Where Cream Is Not the Answer
There are a few situations where cold sore cream may not be the right option.
Cold sore cream is designed for use on the skin around the lips. Follow the instructions for your specific product and do not apply it inside the nose or mouth or near the eyes unless the product information specifically says it is suitable there.
Antiviral treatment may be more helpful when started early, such as when you first notice tingling or other early symptoms. Once a cold sore has fully developed or crusted, the benefit may be more limited.
Cream is also not the right treatment for every type of herpes infection. A severe or widespread outbreak, a first ever episode, or suspected genital herpes may need assessment and different treatment.
Aciclovir Tablets in Pregnancy
Oral aciclovir may be prescribed during pregnancy when clinically appropriate. This can include some first episodes of herpes simplex, severe outbreaks or frequent recurrences where preventive treatment is considered.
The available evidence is generally reassuring. A large Danish population based cohort found no increased rate of major birth defects among pregnancies exposed to aciclovir during the first trimester compared with unexposed pregnancies.
This is useful human evidence rather than information based only on animal studies. Registry data have also been generally reassuring, with most exposed pregnancies resulting in live births without major birth defects.
However, no study can rule out every possible risk. The decision to use aciclovir during pregnancy should therefore be made with your prescriber or maternity team, based on your symptoms, medical history and the reason treatment is needed.
This page does not give a dose or treatment schedule. The right amount and duration depend on what is being treated and your individual circumstances.
Aciclovir exposure alone does not usually mean that you need additional fetal monitoring beyond routine antenatal care. A standard course does not normally require an extra blood test or scan simply because you are taking aciclovir. If you have other health conditions, your maternity team can advise whether any additional monitoring is needed.
Valaciclovir in Pregnancy: Why Aciclovir Is Usually Preferred
Valaciclovir is a prodrug, which means your body converts it into aciclovir after it is absorbed. The active medicine produced is therefore aciclovir.
The main difference is the amount of pregnancy evidence available. In the Danish cohort described above, around 1,561 first trimester exposures involved aciclovir, compared with around 229 involving valaciclovir. Neither medicine was associated with an increased rate of major birth defects in that study.
There is more pregnancy data available for aciclovir, particularly for uncommon outcomes. This is one reason aciclovir may be preferred when either medicine would otherwise be suitable.
Valaciclovir is still used in pregnancy in some situations. Your prescriber can decide which medicine is most appropriate for you rather than you choosing between them yourself.
Aciclovir and Breastfeeding
This is where the available information is generally reassuring.
Tablets While Breastfeeding
Aciclovir does pass into breast milk, but only small amounts are transferred. Even at higher maternal doses, the amount a breastfed baby receives through milk is estimated to be around 1 per cent of a typical infant treatment dose.
Based on this low exposure, aciclovir is generally considered suitable for treating herpes infections during breastfeeding.
Breastfeeding does not usually need to be stopped or timed around your aciclovir doses. Valaciclovir is also generally considered compatible with breastfeeding.
If you are taking aciclovir and notice anything unusual in your baby, or you are simply unsure about continuing to breastfeed, speak to your GP, health visitor, pharmacist or maternity team.
Cream While Breastfeeding
If you are using aciclovir cream for a cold sore on your lip, very little medicine is expected to reach your bloodstream. This means exposure to a breastfed baby is expected to be very low.
The important thing is to keep the baby away from the treated area and wash your hands after applying the cream.
If you need to apply any medicine on or near the breast, check with a pharmacist or healthcare professional first. They can advise on the most suitable product and how to use it without exposing your baby to the medicine.
The One Situation That Changes Things
If you have a herpes blister on the breast or nipple itself, get medical advice promptly. You may be advised not to breastfeed from the affected side while the lesion is present.
Expressed milk from the affected side may also need to be discarded if it could have come into contact with the lesion. Feeding from the unaffected side may still be possible if there are no lesions there.
Newborn babies are particularly vulnerable to herpes infections. With a cold sore, the main concern after birth is direct contact rather than the virus passing through breast milk.
Do not kiss your baby's face while you have an active cold sore. Wash your hands carefully, avoid touching the sore and ask visitors with active cold sores to avoid close contact with the baby until the sore has healed.
Cold Sores and Herpes Simplex in Pregnancy: Why They Can Seem More Frequent
Some people report more frequent cold sore outbreaks during pregnancy. There may be several reasons for this, although there is not one confirmed explanation for everyone.
Pregnancy changes how the immune system responds, and everyday triggers can also play a part. These can include tiredness, disrupted sleep, stress, other illnesses and sun exposure.
Having more frequent cold sores does not necessarily mean that there is a problem with your pregnancy. If your outbreaks become unusually frequent, severe or difficult to manage, speak to your GP, pharmacist or maternity team.
Managing a Cold Sore in Pregnancy Without Reaching for Tablets
Whether or not you use an antiviral, there are some simple things you can do to make a cold sore easier to manage.
- Start treatment early if you are using an antiviral product, following the instructions for your specific medicine
- A cold compress, such as ice wrapped in a clean cloth, may help soothe the area and reduce discomfort
- Keep the area clean and avoid picking or scratching the sore, as this can irritate the skin and may increase the risk of a bacterial infection
- Use a plain, unmedicated lip balm if the area becomes dry or cracked. An SPF lip product may also be useful outdoors because sunlight can trigger cold sores in some people
- Wash your hands before and after touching the area
- Do not share towels, flannels, cups, cutlery or lip products
- Get enough rest and drink enough fluids, unless you have been advised to limit your fluid intake
Painkillers, Which Nobody Mentions
A cold sore can be painful, and you may want to take something to help. During pregnancy, it is worth checking that your choice of painkiller is suitable.
Paracetamol is generally considered the first choice for pain relief during pregnancy when it is appropriate for you. Use the lowest effective dose for the shortest time needed and follow the instructions on the pack or advice from your healthcare professional.
Anti inflammatory painkillers such as ibuprofen are generally not recommended during pregnancy unless a healthcare professional has advised you to use them. They are particularly unsuitable during the later stages of pregnancy.
If you are unsure which painkiller you can take, ask a pharmacist, GP or midwife.
One Trigger Myth to Drop
You may have heard that certain foods can trigger cold sores, often linked to the idea that foods containing arginine encourage outbreaks while lysine prevents them.
The evidence for dietary changes is mixed, and there is not enough evidence to recommend cutting out particular food groups to manage cold sores. This is especially worth keeping in mind during pregnancy, when a balanced diet is important.
When Genital Herpes Needs More Than Self Care
Contact your midwife, GP or maternity team rather than trying to manage the situation alone if:
- You think you may be having a first ever genital herpes episode during pregnancy. Prompt assessment may be needed to confirm the diagnosis and discuss treatment
- You have genital herpes and are approaching your due date. Your maternity team may discuss antiviral treatment later in pregnancy if appropriate for you
- An outbreak is severe, spreading or making it difficult for you to eat or drink
- You feel generally unwell or have a temperature
- A cold sore affects the eye. Eye involvement needs prompt medical assessment because herpes can affect the eye and vision
- You have eczema and develop spreading blisters, as this can need urgent medical treatment
- You have a weakened immune system for any reason
- You are concerned about a newborn who becomes unusually sleepy or floppy, feeds poorly, develops a temperature or develops a blistering rash
For reassurance, a cold sore on your lip is not a route of transmission to a baby in the womb and is not the same as genital herpes. A cold sore on the lip does not usually change your delivery plan.
The precautions that matter with cold sores are mainly after birth, when direct contact between the sore and a newborn can pass the virus.
Who to Ask
Healthcare professionals, including obstetricians, midwives, GPs and pharmacists, can consider your stage of pregnancy, medical history and any other medicines you are taking when advising you about treatment.
A pharmacist can also advise you about treatments that may be suitable to buy from a pharmacy and whether you need to see another healthcare professional.
An online pharmacy consultation is not a substitute for maternity care. If you are pregnant or breastfeeding and are unsure about treating a cold sore, speaking to a healthcare professional is a good place to start.
Medical Disclaimer
This article is provided for general information only and does not constitute medical advice. It is not a substitute for a consultation with a qualified healthcare professional, and it does not tell you what to take or at what dose.
If you are pregnant, planning a pregnancy or breastfeeding, speak to your midwife, GP, obstetric team or pharmacist before starting, stopping or changing any medicine, including medicines bought without a prescription. Always follow the instructions on the pack, your pharmacy label and the patient information leaflet, including instructions about where a product may and may not be applied.
Seek prompt medical advice if you think you may have a first genital herpes episode during pregnancy, have an outbreak near your due date, develop symptoms affecting the eye, develop spreading blisters with eczema, or have any concerns about a newborn baby.
