Medically reviewed by Casey Gallagher, MD Armpit rashes often develop due to allergic reactions, infections, and chronic conditions. Rashes are common under the arms because the skinfold creates a ...

Syphilis is another type of bacteria that can form a rash on the stomach. It is during the secondary stage of syphilis that a rash on the stomach can form. It is also seen on the hands and feet.

Tertiary syphilis, which can develop years to decades after the initial infection, is characterized by chronic inflammatory ...