Which STDs Cause a Rash?

Secondary syphilis causes a rash that notably includes the palms and soles — a location pattern that's genuinely distinctive and worth knowing, since most everyday rashes don't follow it. Acute HIV infection can cause a mild, flat-to-slightly-raised rash on the trunk during the initial flu-like phase, two to four weeks after exposure. Herpes causes clustered blisters rather than a diffuse rash — a different presentation than the others, more localized and progressing through a distinct blistering and crusting cycle.

A rash by itself, without other context, is more likely to be something unrelated to an STD — contact dermatitis, a heat rash, a reaction to a new product, or a viral illness unrelated to sexual activity. The details that shift the picture are the ones covered above: location on the palms and soles specifically, timing relative to a specific exposure, and whether it's accompanied by other symptoms like fever or swollen glands.