Herpes Simplex in Newborns (Neonatal Herpes)
Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist
Content reviewed against published AAP, CDC guidelines
Last reviewed:
If your baby has been diagnosed with or you suspect herpes simplex in newborns (neonatal herpes), here is what the evidence says.
The short answer
Neonatal herpes is a rare but serious infection caused by the herpes simplex virus (HSV), most often transmitted during delivery. It can also be transmitted after birth through contact with cold sores or herpes lesions. Early recognition and treatment with antiviral medication (acyclovir) are critical. Prevention includes cesarean delivery if active genital lesions are present and avoiding contact between cold sores and the baby.
Key takeaways
- Neonatal herpes is a rare but serious infection caused by the herpes simplex virus (HSV), most often transmitted during delivery. It can also be transmitted after birth through contact with cold sores or herpes lesions. Early recognition and treatment with antiviral medication (acyclovir) are critical. Prevention includes cesarean delivery if active genital lesions are present and avoiding contact between cold sores and the baby.
- Usually normal when: Baby has no blisters, vesicles, or concerning symptoms despite known herpes exposure, and monitoring period has passed
- Call your doctor if: Any blisters, vesicles, or clusters of sores on your newborn's skin, mouth, or eyes require immediate emergency evaluation
- Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
Parents everywhere have the same worry. You are doing the right thing by looking into it.
What Parents Should Know
According to AAP, CDC guidelines, neonatal herpes is a rare but serious infection caused by the herpes simplex virus (HSV), most often transmitted during delivery. It can also be transmitted after birth through contact with cold sores or herpes lesions. Early recognition and treatment with antiviral medication (acyclovir) are critical. Prevention includes cesarean delivery if active genital lesions are present and avoiding contact between cold sores and the baby. At 0-1 month, neonatal herpes most commonly presents in the first 2-4 weeks of life. It can appear as skin vesicles (small blisters), eye infection, mouth sores, or in severe cases, can affect the brain (encephalitis) or multiple organs (disseminated disease). Risk is highest when the mother has a primary (new) genital herpes infection near delivery. Any newborn with blisters, vesicles, or signs of illness should be urgently evaluated. Treatment with intravenous acyclovir is started immediately when herpes is suspected. After birth, anyone with an active cold sore should not kiss the baby and should practice strict hand hygiene. It is generally considered normal when baby has no blisters, vesicles, or concerning symptoms despite known herpes exposure, and monitoring period has passed. However, you should contact your pediatrician promptly if any blisters, vesicles, or clusters of sores on your newborn's skin, mouth, or eyes require immediate emergency evaluation.
Normal vs. Concerning
By Age
What to expect by age
0-1 month
Neonatal herpes most commonly presents in the first 2-4 weeks of life. It can appear as skin vesicles (small blisters), eye infection, mouth sores, or in severe cases, can affect the brain (encephalitis) or multiple organs (disseminated disease). Risk is highest when the mother has a primary (new) genital herpes infection near delivery. Any newborn with blisters, vesicles, or signs of illness should be urgently evaluated. Treatment with intravenous acyclovir is started immediately when herpes is suspected. After birth, anyone with an active cold sore should not kiss the baby and should practice strict hand hygiene.
1-3 months
Herpes infection can still occur through contact with active lesions. If your baby was treated for neonatal herpes, they will typically receive oral suppressive acyclovir therapy for 6 months to prevent recurrence. Continue to protect your baby from exposure to cold sores.
3-6 months
If treated early, many babies with neonatal herpes recover well. Babies who had skin, eye, or mouth disease have the best outcomes. Those who had brain or disseminated disease may need developmental follow-up. Continue antiviral prophylaxis as prescribed.
6-12 months
Ongoing monitoring continues for babies who had neonatal herpes. Developmental assessments may be recommended for those who had CNS involvement. The risk of herpes transmission from cold sores and skin contact continues to require vigilance.
What to Tell Your Pediatrician
- Describe when you first noticed herpes simplex in newborns (neonatal herpes) and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby was exposed to someone with an active cold sore or herpes lesion.
- Mention if you have a history of genital herpes and want to discuss risk and prevention.
- Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
- Bring a list of any questions or observations you want to discuss at the appointment.
What Should You Do?
When to take action
- Baby has no blisters, vesicles, or concerning symptoms despite known herpes exposure, and monitoring period has passed
- Your baby was exposed to someone with an active cold sore or herpes lesion
- You have a history of genital herpes and want to discuss risk and prevention
- You notice any unusual skin lesions on your newborn
- Any blisters, vesicles, or clusters of sores on your newborn's skin, mouth, or eyes require immediate emergency evaluation
- Baby becomes lethargic, refuses to feed, develops a fever, or has seizures, which could indicate disseminated or CNS herpes
What You Can Do at Home
- Keep track of when you notice herpes simplex in newborns (neonatal herpes) — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that baby has no blisters, vesicles, or concerning symptoms despite known herpes exposure, and monitoring period has passed — this is generally within the range of normal.
- At 0-1 month, focus on observation rather than intervention unless your pediatrician advises otherwise.
- Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
- While monitoring at home, seek immediate care if any blisters, vesicles, or clusters of sores on your newborn's skin, mouth, or eyes require immediate emergency evaluation.
Related Conditions
Signs of Infection and Sepsis in Newborns
Neonatal sepsis is a serious bacterial infection in the bloodstream that can develop in the first month of life. Signs are often subtle and can include temperature instability, poor feeding, lethargy, irritability, rapid breathing, and a "just not right" appearance. Neonatal sepsis is a medical emergency requiring immediate antibiotics. Trust your instincts if your newborn seems unwell.
Eye Infection and Discharge in Newborns (Conjunctivitis)
Eye discharge in newborns is common and can be caused by a blocked tear duct (most frequent), chemical irritation from eye prophylaxis, or infection. While most sticky eyes are harmless, any significant redness, swelling, or pus-like discharge in the first month should be evaluated promptly, as certain infections can damage the eye.
Related Resources
Frequently asked questions
Is herpes simplex in newborns (neonatal herpes) normal?
When should I call the doctor about herpes simplex in newborns (neonatal herpes)?
When is herpes simplex in newborns (neonatal herpes) normal?
What causes herpes simplex in newborns (neonatal herpes)?
What should I mention to my pediatrician about herpes simplex in newborns (neonatal herpes)?
Is herpes simplex in newborns (neonatal herpes) normal at 0-1 month?
Is herpes simplex in newborns (neonatal herpes) normal at 1-3 months?
Should I go to the ER for herpes simplex in newborns (neonatal herpes)?
Does herpes simplex in newborns (neonatal herpes) go away on its own?
References
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Herpes Simplex in Newborns (Neonatal Herpes).
Things to mention
- Describe when you first noticed herpes simplex in newborns (neonatal herpes) and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby was exposed to someone with an active cold sore or herpes lesion.
- Mention if you have a history of genital herpes and want to discuss risk and prevention.
- Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- Your baby was exposed to someone with an active cold sore or herpes lesion
- You have a history of genital herpes and want to discuss risk and prevention
- You notice any unusual skin lesions on your newborn
Urgent signs to report immediately
- Any blisters, vesicles, or clusters of sores on your newborn's skin, mouth, or eyes require immediate emergency evaluation
- Baby becomes lethargic, refuses to feed, develops a fever, or has seizures, which could indicate disseminated or CNS herpes
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members
Related Resources
Bottom line
Most cases of herpes simplex in newborns (neonatal herpes) are normal. Talk to your pediatrician if any blisters, vesicles, or clusters of sores on your newborn's skin, mouth, or eyes require immediate emergency evaluation.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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Related Medical Concerns
Signs of Infection and Sepsis in Newborns
Neonatal sepsis is a serious bacterial infection in the bloodstream that can develop in the first month of life. Signs are often subtle and can include temperature instability, poor feeding, lethargy, irritability, rapid breathing, and a "just not right" appearance. Neonatal sepsis is a medical emergency requiring immediate antibiotics. Trust your instincts if your newborn seems unwell.
Eye Infection and Discharge in Newborns (Conjunctivitis)
Eye discharge in newborns is common and can be caused by a blocked tear duct (most frequent), chemical irritation from eye prophylaxis, or infection. While most sticky eyes are harmless, any significant redness, swelling, or pus-like discharge in the first month should be evaluated promptly, as certain infections can damage the eye.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.
Adenoid Hypertrophy and Breathing
Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.
Adrenoleukodystrophy (ALD) in Babies
X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder affecting about 1 in 17,000 newborns, caused by mutations in the ABCD1 gene on the X chromosome. It primarily affects boys and impairs the breakdown of very long-chain fatty acids (VLCFAs), which accumulate and damage the myelin sheath in the brain and the adrenal glands. The most severe form, cerebral ALD, typically affects boys between ages 4-10 with rapid neurological decline. Newborn screening now enables early detection, and hematopoietic stem cell transplant or gene therapy performed before significant brain involvement can be life-saving.