Fever blister when sick
A fever blister is usually a recurrent herpes simplex lesion on or around the lip that can reactivate during illness or stress.
The short answer
A fever blister is usually a recurrent herpes simplex lesion on or around the lip, and illness or stress can coincide with its reactivation.
How should you care for a fever blister without spreading it?
Keep it clean, do not pick it, and wash hands after touching it.
How can you avoid passing an active fever blister to others?
Avoid kissing and sharing lip products, utensils, or toothbrushes while active.
When does a fever blister need dental or medical review?
Seek care for an eye-area lesion, widespread blisters, dehydration, or a nonhealing sore.
What should you ask about identifying and treating the lesion?
Ask whether the lesion fits a cold sore and whether early antiviral treatment is suitable.
Frequently asked questions
What is the main thing to know?
A fever blister is usually a recurrent herpes simplex lesion on or around the lip, and illness or stress can coincide with its reactivation.
When should I arrange an examination?
Seek care for an eye-area lesion, widespread blisters, dehydration, or a nonhealing sore.
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Who wrote this page
This library is published by Dental Nation, a licensed dental group practising in the United Arab Emirates. Pages are written and overseen by the same clinical team that treats patients in our clinics, and are held to a fixed editorial standard for safety and accuracy.
This page is patient education, not medical advice, and cannot replace an examination. Anything urgent — facial swelling, trauma, uncontrolled bleeding or severe pain — needs a dentist or emergency care now.