wrinkle irritation on tail

Depends on why the irritation is there. Have you had a vet check the area out? It could be demodex, allergy, bacterial infection, ring worm, sarcoptic mites or the area could have been scraped and appears red. Theres so many different issues and you dont want to try to treat something without having an idea about what your contending with.

Good luck and welcome to the forum!!!

Can't be sarcops or the first word in the post would have been ITCHES in fold on tail.  And unless it's a young puppy let's hope it's NOT demodex or there is a huge problem in a mature dog.

Breeds that are wrinkley (like sharpei's, pugs, etc.) tend to have skin folds that develop yeast -- and tea tree oil can help there -- but you don't want it where they can lick it.

First stop IS the vet -- and if you have a diagnosis of yeast then we can help.

It's so hard to help or offer advise without first seeing a picture of the little guy!!!!   :)

I'm with the others in thinking a vet visit wouldbe a good idea.

Good luck and welcome.

I swear by Gold Bond powder on all sorts of skin issues.  The other option is antifungal powder.  Most irritation you want to keep dry.  So powder is good. 

On the other hand, I've heard of people using olive oil in the skin folds of dogs with wrinkles.  I guess you do have to know what you are dealing with.  The thing about Gold Bond is that you can hardly do no wrong with it.  And it seems to be soothing to the dogs.  My bullies won't even lick it off their feet when I use it.  The "green" can is best.  But sometimes you can't find it.  So the "yellow" can must do.

 Good luck sorting this out!