Strep Throat


What is Strep throat and what causes it? Strep throat (also called “acute pharyngitis” or “Streptococcal pharyngitis”) is a bacterial¬† infection of the throat and tonsils. It is caused by a bacterium called Streptococcus pyogenes (“Pie-AW-Jen-Eez”), belonging to Group A Streptococci (GAS). There are many different strains of Group A Streptococci, each capable of producing slightly different degrees of severity and/or symptoms.

Strep throat is most common in the winter months or around winter time. It is most commonly seen in school-aged children and teens but also occurs in adults and children under three. Most sore throats are viral, not Strep.

Group A Streptococci are found all over and are the most common bacterial cause of acute pharyngitis in humans- accounting for up to 30% of cases in children and 10% in adults. In addition to acute pharyngitis, GAS can cause impetigo (skin disease), and less commonly, pneumonia, cellulitis (skin infection), otitis media (inner ear infection), sinusitis (sinus infection), bacteremia (blood stream infection), necrotizing fasciitis (severe infection of the tissues below the skin), meningitis (infection around the brain), and Toxic Shock Syndrome.

S. pyogenes has an outermost capsule that helps it escape detection by the human immune system, allowing it to colonize in your upper respiratory tract. At any time, it can overwhelm your host defenses and cause disease.

What are the signs and symptoms of Strep throat? The “classic” findings for Strep throat are:



  1. Fever (above 100.4 F)
  2. White or gray patches on the tonsils
  3. Tender and swollen lymph glands in the neck
  4. Absence of cough

These symptoms and signs (the Centor Criteria) are non-specific and even if you have all four, the odds are only about 60% probability of Strep. Symptoms of Strep throat start 2-5 days after exposure, usually rather suddenly.

Other findings in Strep throat include: headache, malaise, red and swollen tonsils, difficulty or pain on swallowing, chills, loss of appetite, rash, bad breath, abnormal taste, and nasal congestion. Children may experience nausea, vomiting, or abdominal pains.

You should call your doctor if you develop signs or symptoms of Strep throat, even if you don’t know if you were exposed to someone with it.

How is Strep throat diagnosed? In addition to a physical examination, your doctor can take a mucus sample from the back of your throat using a long cotton swab. Using the Rapid Strep Test, he/she can have the test result in about 15 minutes. Your doctor can also take a sample of your throat mucus and send it to the lab for culture. This is more reliable but it takes up to 2-3 days. Sometimes the Rapid Test comes back negative (meaning you don’t have Strep throat) but your doctor may do the culture to be sure, because sometimes the Rapid Test can miss a case. If the Rapid Test is positive, there is no need to culture. Most cases of sore throats are viral and Strep cannot be diagnosed accurately by symptoms alone.

How is Strep throat treated? Although Strep throat usually gets better on its own, your doctor will treat you with antibiotics, to shorten the course of disease, decrease the time you are contagious, and to decrease your chances of getting a serious complication of strep infection, such as Rheumatic Fever or kidney inflammation. Not all antibiotics will kill S. pyogenes, so it is important for you to take the one prescribed by your doctor for this infection, and not one for another infection that you still had in your medicine cabinet. It is also very important to completely finish the full course of antibiotic and not stop once you start to feel better. Nearly all symptoms of Strep throat are gone within a week. Viral sore throats do not require or respond to antibiotics.

If you don’t start getting better after 1-2 days of treatment, call your doctor.

Is Strep throat contagious? YES! Until you have been on antibiotics for several days, you can still spread the Strep germ to others. You can help prevent the spread by frequently washing your hands, covering your mouth when coughing or your nose when sneezing, and not sharing eating utensils or drinking glasses. Properly dispose of used tissues. Avoid close contact with others who have been diagnosed with Strep throat until their symptoms are gone. Since bacteria can survive for a short time on doorknobs, water faucets, and other objects, it’s a good idea to wash your hands regularly. You should probably stay home from school or work for 24-48 hours after starting antibiotics.

Important tip: Get a new toothbrush after you are no longer contagious but before you finish the antibiotics. This will keep you from reinfecting yourself. Also, keep your toothbrush separate from other family members.

What else can I do to feel better? Most important, get plenty of rest- this will help your body fight the infection. Drink several cups of water each day to stay well hydrated. Take acetominophen (like Tylenol) or ibuprofen (like Advil or Motrin) for fever or pain. Avoid giving aspirin or any salicylate product to children under 19, as they may develop a serious condition called Reye’s Syndrome. Eat soft foods, and drink cool drinks or warm liquids. Avoid eating acidic or spicy foods. Gargling with warm salt water (1/4-1/2 tsp salt in 8 oz water) several times daily may help. Lozenges or popcicles will help soothe the throat. Avoid smoking.

Where can I learn more?

CDC/Dept of Health and Human Services

American Academy of Family Physicians