The symptoms most commonly associated with strep throat are high fever, pus coming out of the tonsils, and a sore throat. Less common symptoms might include things like headaches, abdominal pains, and nausea. You can also get a rash from strep throat, but usually this will be a symptom of an associated condition, called scarlet fever. The rash typically begins on the face or neck, though it can also spread to cover the entire body. The same type of medication used to treat the initial streptococcus infection will generally treat scarlet fever as well, so while a rash associated with strep throat may be alarming it may not be too serious if treatment is sought.
Historically, a rash from strep throat and the associated scarlet fever were potentially very serious. Scarlet fever can result from the streptococcus bacteria releasing an exotoxin into the blood. This is usually a complication of strep throat, though it can also be precipitated by streptococcal skin conditions, such as impetigo. In either case, complications ranging from secondary infections to meningitis and even sepsis can occur, and were, in fact, far more prevalent historically. Many of these complications may be moderated or even avoided by seeking treatment and undergoing a prescribed antibiotic series as soon as you develop a rash from strep throat, or even before.
The rash itself can be unsightly or even uncomfortable, and will generally appear paler than unaffected skin when pressure is applied to it. After about a week it should start to fade, and peeling often begins. Since you stop being infectious about 24 hours after beginning a course of antibiotics, it can be possible to exhibit a rash from strep throat without actually being contagious. On the other hand, someone may appear symptom-free and healthy for up to a week after having been infected.
Strep throat and scarlet fever are both caused by the streptococcus bacteria. Viral sore throat is unrelated to these conditions, and can be caused by any number of infections. Certain viral sore throats may appear strep-like and even exhibit accompanying rashes. Mononucleosis, in particular, may have many symptoms in common with strep throat, including sore throat and discharge from the tonsils. It may also have an associated rash. It is important to receive a correct diagnosis, as antibiotics that can easily treat bacterial infections, like strep, but will have no effect on viral sore throats.