I normally wouldn't double post but I wouldn't like this to get lost as a lot of people are really suffering with this and not one post out of hundreds has looked at this problem this way - GOOD NEWS: TREATED SUCCESSFULLY AS FRICTION BURNS AND HEAT ALLERGY
I had this syndrome with only some temporary relief for about 6 months. I read these boards and it was frightening. And then one good conversation with a thoughtful, progressive doctor sorted everything out.
My problem started with a trimming incident - I nicked my scrotum in a couple of places and a few days later I woke up after a night of sex with the whole area - scrotum and penis bright red, burning and itching.
My first visit to the doctor, after reading these boards, resulted in her suspecting a staph infection, prescribing antibiotics and sending me to an STD clinic.
My symptoms more or less remained - the redness on the penis reduced to few patches on the underside but by the time I went to the clinic all was left was a red scrotum ... and what do you know? The morning of the appointment it had (temporarily) gone, they could see nothing wrong but prescribed an anti-fungal & mild steroid cream which provided a little temporary relief.
Most days the scrotum remained hot and itchy and I had the feeling of hot sand being sprinkled on my penis, The skin seemed thinner and the foreskin a little tighter.
After a few months following advice from here, using Lanacane powder etc and keeping the complaint minimised without getting rid of it, I went back for a long chat with my young doctor.
She differentiated between the redness on the penis and scrotum, speculating that as the redness on the scrotum could come and go quickly it was primarily a way for the area to lose heat. More blood fills the veins near the surface to cool it.
The redness on the penis may be partly physical friction burns and partly an allergic reaction to heat. She prescribed anti-histamine tablets, suggested using a powerful re-moisturiser and using body lotion instead of soap in the bath/shower.
I got some Eucerin - 'Intensive 10% w/w Urea Treatment Lotion' and used this in the mornings after a moisturising bath ... and haven't suffered since.
One thing I didn't notice at the time is that I see my girlfriend twice a week (we're both single parents - I'm 49, she's 45) - midweek during the day and Saturday nights. After the weekend I would be left with a red sore ring around my foreskin and extra red scrotum - but not so much after our midweek daytime sessions.
I carefully addressed this sensitive issue with my partner. Often we don't get in till late on Sunday morning after partying till late - with the tiredness and the drinking etc we weren't noticing that maybe we should be using some lubrication like KY jelly - at night and again in the morning. During the week it's obviously not necessary as we take our time. She obviously felt bad about this (as an age issue) but credit to her, she recognised the problem ("just warm it up in your hands first!").
Many of the posts on this syndrome have started with something like "I had casual sex with someone" - with the fear that it's an STD. I'd say that it was more likely the lady wasn't fully juiced up, resulting in a friction burn with a possible allergic reaction. The scrotum then reddens to help the area lose heat.
Others have said that tight cotton briefs and corn powder give greater relief than loose boxers - I'd say that that reduces friction and involves less rubbing/aggravation in the area but will in other ways not address the problem of oil-dryness and over-heating.
It seems that as we get older it's possible to lose moisture in the area which doesn't replenish easily. Many report that the area is moist - but that's a different kind of moisture - sweat; which is another way that the body can lose heat, but it's primarily water and the saltiness will dry the skin of necessary oils even more.
Another aspect of this goes back to when it started for me (and others that have posted) - with trimming. The nicks in the skin probably weren't significant. What is pubic hair for? As I understand it, it's to reduce friction (like under the arms). Shorter hair - with the sharp tips you get after trimming (I also often trim my girlfriend at the same time) - coupled with lack of full vaginal lubrication, is going to result in more friction and more heat and potentially kick off a greater allergic reaction. Well, that's all I got for now ... BUT IT'S WORKED FOR ME