Listed below are some other conditions sometimes Mistaken for herpes:
Bacterial or yeast infections
do not usually produce blistering
Canker sores (aphthous ulcers)
are gray with a distinct edge
usually occur inside the mouth
usually heal within 10-14 days without treatment
Impetigo
is a highly infectious bacterial disease
often produces crusty blisters
is more common among children
Molluscum contagiosum (molluscum)
like herpes, molluscum is a viral infection of the skin
unlike herpes, molluscum produces lesions that are raised, with a central dimple
Syphilis
is a bacterial infection
causes chancres sometimes mistaken for blisters caused by genital herpes
Unlike genital herpes, Syphilis does not usually produce a cluster of blisters, and it usually responds well to antibiotics.
Source: http://www.herpes-coldsores.com/std/herpes.htm
