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.

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.

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 winter and early spring. Strep bacteria flourish wherever groups of people are in close contact.

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
• Poststreptococcal reactive arthritis, a condition that causes inflammation of the joints