Strep throat, which causes a painful, scratchy sore throat, affects people of all ages. Most sore throats are caused by a virus and typically resolve on their own, but strep throat results from a bacterial infection of the throat and requires prompt treatment. A strep infection left untreated causes complications, such as a rash, and can even result in kidney inflammation.
Adults with strep throat may experience a complication that affects the tonsils--lymph nodes located on the top of the throat. The tonsils help the body by filtering out microorganisms, thus preventing infection. When the tonsils have trouble filtering out the strep bacteria, they swell and become inflamed, resulting in tonsillitis. Symptoms of tonsillitis include reddened, swollen tonsils with white spots, tenderness of the jaw and throat when touched, difficulty swallowing, fever and headache. Antibiotics are used to fight the infection. The University of Maryland Medical Center reports symptoms usually subside in two to three days after initiation of antibiotic therapy. Typically, one course of antibiotics cures the infection although some tonsillitis infections require more than one course.
An untreated strep infection often results in the complication known as scarlet fever. Scarlet fever accompanies already existing symptoms of strep throat, reports the National Institute of Allergy and Infectious Diseases (NIAID). Scarlet fever starts out as a red rash, usually on the chest and abdomen, before spreading over most of the body. The rash consist of tiny bumps that feel like sandpaper when touched. The skin folds, if affected, become a darker red color. The tongue displays a strawberry-red color and the face appears flushed. The Mayo Clinic recommends medical treatment when any signs and symptoms of strep throat or complications are identified.
According to Medline Plus, after an untreated strep infection, the kidneys become infected with the strep bacteria, resulting in the disorder known as post-streptococcal GN. The infection affects kidney function, which causes inflammation and problems with filtering urine. Symptoms of post-streptococcal GN include a decrease in urine output, urine with visible blood, a swelling of the abdomen, face, or eyes and swelling of the lower extremities, such as the feet or ankles. Other symptoms associated with the disorder affect the joints, causing pain and stiffness. Medline Plus reports no specific treatment for post-streptococcal GN but antibiotics are necessary to destroy any remaining strep bacteria present in the body. Adults dealing with post-streptococcal GN as a result of an untreated strep infection usually find the disorder resolves itself within a few weeks or months, but in some the disorder progresses into chronic kidney failure.