Red spots on glans penis are not always serious. In some cases, red spots may result from allergic to chemicals, soap, salt water in a beach, chemical water in a pool, poor hygiene or a minor irritation. These spots typically disappear in a day or two. Red spots that develop as a result of something more serious, such as a sexually transmitted diseases typically last longer and are accompanied by other symptoms. Read on to learn what symptoms to watch for, how each condition might be treated, and when to see your doctor.