A rash around the groin and buttocks is most often Jock itch or tinea cruris which causes redness, peeling and flakiness or cracking of the skin in your groin, thigh and buttock areas.
The jock itch rash can be circular in appearance with well defined or elevated edges and can also spread to the area around your anus.
A rash on the inner thigh and buttocks can be several different things which include a heat rash, irritation, contact dermatitis, chafing, jock itch, razor burn, swimmer's itch or hidradenitis suppurativa.
Jock itch (or tinea cruris) usually causes redness, flakiness, peeling, or cracking of the skin in the groin, thigh, and buttocks area.
The rash can look circular, with well-defined or even elevated edges.
It can also spread to the area around the anus (where poop comes out).
A syphilis rash might also be made up of large, raised gray to white lesions with a moist finish.
These types of syphilis rashes occur on the inner thighs, armpits, groin, or below the breasts.
Because syphilis rashes are very pale and not itchy or painful, they can be easy to overlook.
You can help clear up the rash on your inner thighs and buttocks by applying some diaper rash cream or petroleum jelly.
You can use petroleum jelly to lubricate and protect the skin.
It might also prevent clothing from causing friction against your inner thighs.
Apply about a teaspoon of petroleum jelly to the inside of your thighs.
You can also try chafing creams and balms, such as Body Glide, or zinc oxide ointment.