These are painful and tender vesicles on the outer surface of lips, and is commonlv observed in
- Acute lobar pneumonia (often gives clue to the side affected and stages of pneumonia)
- Influenza.
- Malaria.
- Meningococcal meningitis.
- Weil's disease.
- Mycoplasma pneumoniae infection.
- AIDS.
- Herpes labialis may be normally seen in females during menstruation.
