Brief Answer:
Most likely infection

Detailed Answer:
Hello and welcome,

I am Dr Madhuri a Gynecologist and will be answering your query.

I understand that you are having an itching in the part of the penis that is covered by a skin fold. It is called the glans penis.

The common causes of itch are infections that may be due to bacteria or fungi. Sometimes allergy to condoms [ in sexually active people or even allergy to undergarments [ especially if they are not made of pure cotton] also cause an itch. The itching due to infection may have a discharge and there may be associated redness. So please check if these are present.

Other reasons for itch may be a condition called lichen planus where there is thickening of skin and itch. Scabies is a parasite that may reside in the skin and cause an itch. Usually there are red spots where the parasite burrows inside and the itch is severe.

Psoriasis is excessive growth of upper skin layers but it causes a typical silver scaly area that looks just like dandruff but is shiny. Seborrhea or excessive production of sweat and sebum by the akin glands also leads to itch.

However the commonest cause is infection. So I advise that it is best to get an examination and a penile swab test to detect infection. If it is a fungus then ointments like clotrimazole twice daily help. If bacterial, then clindamycin ointment is useful.
Other measures include keep the area clean after retracting the fore skin using a mild antiseptic soap like savlon once a day at morning [ please apply only a tiny bit first and see if you experience irritation, if yes then do not use] and dove at night. Keep the area dry and do not scratch as scratching will aggravate the infection.

Use of surfaz Sn ointment twice daily will help in providing relief if used for 7 days. Wash the undergarments in hot water and change them twice daily to prevent reinfection.

Hope this satisfies your query.
Thanks for using HCM.     
Feel free to ask any more questions that you may have.
Dr Madhuri Bagde
Consultant Obstetrician and Gynecologist

---