Brief Answer:
Hi,

Detailed Answer:
Inflammation of head of penis i.e. penile swelling, is a symptom of health condition & not a condition itself. It usually shows with other symptoms, which can range from mild to severe.
Balanitis, is a common cause of penile swelling/inflammation. Apart from swelling the other symptoms may be- redness, itchiness, foul odour, shiny thick skin, painful urination, sores & presence of smegma ( Thick white discharge under fore-skin ). The main causes of this swelling may be-
Poor hygienic habits mostly associated with uncircumcised males
Allergic or irritant reactions ( Contact dermatitis ) due to latex condoms, propylene glycol in lubricants, spermicides, chemicals in soap & lotions or chlorine in bathing water etc.
Besides the contact dermatitis, the other common cause may be overgrowth of cadida albicans- a type of yeast & bacterial balanitis due to streptococcus or staphylococcus species.
Recurring balanitis may be associated with poorly managed diabetes or immunodeficiency.
The treatment of the condition is treatment of the cause. If , you think some allergic or irritant factor, it should be eliminated from the contact. Maintainance of proper hygiene & if the condition become recurrent, then circumcision may also be planned.
If you are having diabetes, it should be controlled properly.
Usually, it is not an STD , however, the symptoms may be transmitted by physical contact in cases of infective cause by yeast or bacteria.
Application of local steroid of low strength like hydrocortisone , anti- bacterial ointment or anti-fungal ointment may usually resolve the problem. If the decision about cause seems difficult, then local ointmenT having combined properties like steroid, antifungal & anti- bacterial may be used.
OTC anti-allergics like cetrizine or loratidine orally may give relief in allergic balanitis.
However, if the above measures do not give relief, then you are advised to see your doctor for proper evaluation & management accordingly, as you may need anti-fungal or anti bacterial treatment orally or by injections.

Regards,

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