Thanks for your question.
You can develop rashes on the penis for many reasons such as that it can be due to a sexually transmitted disease. They are also caused because of some sort of allergic reaction to an irritant which comes in contact with the skin. It also forms infections from fungus, bacteria, or parasites. Men who have chronic conditions that causes rash include eczema or psoriasis may find that it affects the penis as well as the surrounding skin.
Some of the common symptoms of rashes on the penis are: swollen as well as the raised patches on any part of the penis. More so, the in these areas show redness also which results in itchiness. In such cases irritation actually increases the symptoms. Hence, you must try to avoid it. You will find that these areas usually dry and often it becomes scaly. The rash tends to stay if not treated early. Moreover, the symptoms will appear again.
In order to treat these rashes you should apply moisturizers so as to reduce the dryness. Injections can also be advised by the doctor. A complete healing takes place within two to three weeks.