Blister On Head Of Penis, Not Painful. What Could This Be?
Considering the fact that it was only one blister, which disappeared on its own, it would be rare that it should be a sexually transmitted infection. It is important to consider a traumatic cause in this case. The nature of the pants you wore is important to be considered. Pure Cotton pants rarely predispose to such symptoms. With no history of risky sexual behaviour, no urethral discharge nor itches, and the fact that you had a singly lesion which is disappearing on its own, painless with no itches, chances that it should be a sexually transmitted infection are faint.
However, watchful look at the lesion is important. Any abnormal signs, new lesions or aggravation of wound or onset of pain or itches should warrant a medical consultation. For now, I suggest dry pure airy cotton pants.
Best regards and hope this helps,
Luchuo, MD.