Cause?
Herpes simplex viruses.
← All explanationsCold sores
When do cold sores become contagious?
Cold sores are caused by herpes simplex viruses. Contagiousness can begin with the first tingling and continues until the affected area has fully healed. Episodes can recur; not every sore on the lip is herpes.
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Early signs
Tingling, burning or itching may precede blisters. An unusual or uncertain lesion needs assessment.
Reduce transmission
Avoid kissing and oral sex during an outbreak. Protect newborn babies in particular. Wash hands after touching the sore and avoid touching eyes with unwashed hands.
Appropriate help
Seek medical advice for severe symptoms, weakened immunity or failure to start healing after about ten days. There is no guaranteed healing deadline.
Read the full explanation
Early signs
Tingling, burning or itching may precede blisters. An unusual or uncertain lesion needs assessment.
Reduce transmission
Avoid kissing and oral sex during an outbreak. Protect newborn babies in particular. Wash hands after touching the sore and avoid touching eyes with unwashed hands.
Appropriate help
Seek medical advice for severe symptoms, weakened immunity or failure to start healing after about ten days. There is no guaranteed healing deadline.
Notes on the teaching images
- Fictional illustration of grouped lip vesicles; not an individual diagnosis.
- Avoid transmission during an outbreak and take special care to protect newborns.
- Symbolic image: seek medical advice for severe, unusual or persistent symptoms.
At a glance
Protect a baby?
Do not kiss during an outbreak.
Eye affected?
Seek prompt medical assessment for pain, redness or vision changes.
Knowledge in motion
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Silent educational film with German on-screen text and simplified teaching images. Not a patient case or a promised treatment outcome. The full English explanation is available as text.
Often confused
Cold sores and aphthous ulcers
Aphthous ulcers are a different type of lesion. An online photograph cannot reliably identify every blister or sore.
Quick answers
Can I attend a dental appointment?
Inform the practice beforehand to agree how to proceed. Still seek prompt advice for urgent dental problems.
Can I kiss my baby?
Not during an active cold sore. Herpes can be dangerous for newborns; seek immediate paediatric help if infection is suspected.
What if an eye becomes red and painful?
Seek same-day eye or urgent medical assessment, particularly with light sensitivity or reduced vision.
At the practice
For a personal discussion
Editorially suggested question to discuss with Dr Niusha Barahmand Pour:
Should the planned appointment be adjusted, and is additional medical assessment needed?
Inform the practice before a planned dental appointment. Seek medical assessment for severe symptoms, weakened immunity or eye involvement.
Discuss appointment arrangementsAppointment selection at DoctolibLearning layer for training & practiceUnderstand terminology and deepen knowledge
- HSV
- Herpes simplex virus.
- Recurrence
- Reappearance after a symptom-free interval.
- Prodrome
- Early signs such as tingling before visible blisters.
Make the distinction
Aphthous ulcers are a different type of lesion. An online photograph cannot reliably identify every blister or sore.
Sources and context
Editorial research: . General information, not an individual diagnosis or treatment recommendation. Teaching illustrations are simplified and do not depict a patient case.