There are many diseases that cause skin rash. According to MedlinePlus, rashes affect the color or texture in a person's skin. The cause of a rash can often be determined based on the observable characteristics of the rash and other accompanying symptoms. It's important to identify and avoid any products that might irritate a the skin and cause a rash. Sometimes, diseases are the cause of skin rashes.
Atopic dermatitis is a disease that causes skin rash. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, atopic dermatitis, also known as eczema, is a chronic or long-lasting disease that affects a person's skin. It is not contagious and cannot be passed between people.
The NIAMS states that atopic dermatitis is characterized by itchy skin that leads to redness, swelling and cracking of the skin, along with clear fluid, crusting and scaling. People with atopic dermatitis often experience flare-ups followed by periods of remission, where no skin rash is present. The NIAMS also notes that atopic dermatitis may disappear entirely as a child grows older, although most people who develop atopic dermatitis as a child retain dry skin that's easily irritated. Some people continue to experience the characteristic symptoms of atopic dermatitis well into adulthood.
Pityriasis rosea is another disease that causes skin rash. The American Academy of Dermatology states that pityriasis rosea is a rash that typically occurs in people between 10 and 35 years of age, although it can occur at any age. The rash can last anywhere from several weeks to several months.
According to the AAD, the pityriasis rosea-related rash typically does not cause permanent marks or scarring, although darker-skinned individuals may experience long-lasting flat brown spots on the skin that eventually fade. Although pityriasis rosea can occur at any point throughout the year, it appears to be most common in the spring and fall. MayoClinic.com states that common signs and symptoms of pityriasis rosea include a herald patch, which is a large, slightly elevated and scaly patch on the back, chest or abdomen, and symptoms of an upper respiratory infection such as headache, stuffy nose, sore throat and mild fever.
According to the U.S. Centers for Disease Control and Prevention, scarlet fever, also known as scarlatina, is a rash-causing disease resulting from infection with group A Streptococcus bacteria. Scarlet fever is characterized by a rash and a strawberry-like appearance of the tongue; it is typically seen in children younger than 18 years of age.
The rash often first appears as tiny red bumps on a person's chest and stomach, but it can quickly spread throughout the body. According to the CDC, the rash usually looks like a sunburn and possesses a texture similar to a piece of sandpaper. It may be redder in certain areas of the body, including the elbow creases, the arm pits and the groin area. The rash lasts for approximately two to seven days, and after it disappears, the skin on the tips of a person's fingers and toes begin to peel.