Strep throat

Signs and symptoms of strep throat can include:

Throat pain that usually comes on quickly
Painful swallowing
Red and swollen tonsils, sometimes with white patches or streaks of pus
Tiny red spots on the area at the back of the roof of the mouth (soft or hard palate)
Swollen, tender lymph nodes in your neck
Fever
Headache
Rash
Nausea or vomiting, especially in younger children
Body aches
It's possible for you or your child to have many of these signs and symptoms but not have strep throat. The cause of these signs and symptoms could be a viral infection or some other illness. That's why your doctor generally tests specifically for strep throat.

It's also possible for you to be exposed to a person who carries strep but shows no symptoms.

When to see a doctor

Call your doctor if you or your child has any of these signs and symptoms:
A sore throat accompanied by tender, swollen lymph glands
A sore throat that lasts longer than 48 hours
A fever higher than 101 F (38.3 C) in older children, or fever lasting longer than 48 hours
A sore throat accompanied by a rash
Problems breathing or swallowing
If strep has been diagnosed, a lack of improvement after taking antibiotics for 48 hours
Causes

The cause of strep throat is bacteria known as Streptococcus pyogenes, also known as group A streptococcus.

Streptococcal bacteria are highly contagious. They can spread through airborne droplets when someone with the infection coughs or sneezes, or through shared food or drinks. You can also pick up the bacteria from a doorknob or other surface and transfer them to your nose, mouth or eyes.

Risk factors

Several factors can increase your risk of strep throat infection:

Young age. Strep throat occurs most commonly in children.
Time of year. Although strep throat can occur anytime, it tends to circulate in late fall and early spring. Strep bacteria flourish wherever groups of people are in close contact.
Complications

Although strep throat isn't dangerous, it can lead to serious complications. Antibiotic treatment reduces the risk.

Spread of infection

Strep bacteria may spread, causing infection in:

Tonsils
Sinuses
Skin
Blood
Middle ear
Inflammatory reactions

Strep infection may lead to inflammatory illnesses, including:

Scarlet fever, a streptococcal infection characterized by a prominent rash
Inflammation of the kidney (poststreptococcal glomerulonephritis)
Rheumatic fever, a serious inflammatory condition that can affect the heart, joints, nervous system and skin
Researchers are investigating a possible link between strep infection and a rare condition called pediatric autoimmune neuropsychiatric disorder associated with group A streptococci (PANDAS). PANDAS is a term used to describe certain children whose symptoms of neuropsychiatric conditions, such as obsessive-compulsive disorder or tic disorders, are worsened by strep infection.

Mayo Clinic