Jock itch can spread to the penis, but that's not common. Instead, this rash tends to focus on the legs and the dark crevices of the body. Herpes, on the other hand, can infect the penis itself, and sores on the head of the penis are quite common. The itching symptoms caused by the two conditions can be quite similar, but the areas in which the itching takes place tend to be quite different.
The appearance of the two conditions is also strikingly different. Where jock itch tends to look a lot like a red rash, with a few tiny blisters on the edge, herpes infections look like heat blisters that are filled with fluid. When these blisters pop, they form painful, crusty sores. Jock itch doesn't behave in this way.
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