What Causes a Sore Throat?

Sore throat is a symptom of many medical disorders. Infections cause the majority of sore throats and can be contagious. Infections are caused either by viruses (flu, the common cold, mononucleosis) or by bacteria (strep, mycoplasma, or hemophilus). While bacteria respond to antibiotics, viruses do not.

Viruses: Most viral sore throats accompany flu or colds along with a stuffy/runny nose, sneezing, and generalized aches and pains. These viruses are contagious and spread quickly, especially in Winter. The body builds antibodies that destroy the virus, a process that takes about a week. Sore throats can accompany other viral infections such as measles, chicken pox, whooping cough, and croup. Canker sores and fever blisters in the mouth also can be painful. One viral infection takes longer than a week to be cured: infectious mononucleosis, or “mono.” This virus hangs out in the lymph system, causing massive enlargement of the tonsils with white patches on their surface and swollen glands in the neck, armpits, and groin. It creates a severe sore throat and sometimes even breathing difficulties. It can affect the liver, leading to jaundice—yellow skin and eyes. It also causes extreme fatigue that can last six weeks or more. “Mono” can be transmitted by saliva and has been nicknamed the “kissing disease.” It can also be transmitted from mouth-to-hand to hand-to-mouth or by sharing of towels and eating utensils.

Bacteria: Strep throat is an infection caused by a particular strain of streptococcus bacteria. This infection can also damage the heart valves (rheumatic fever) and kidneys (nephritis). It causes scarlet fever, tonsillitis, pneumonia, sinusitis, and ear infections. Because of these possible complications, a strep throat should be treated with an antibiotic. Strep is not always easy to detect by examination, and a throat culture may be needed. If positive, the physician may prescribe antibiotics. However, strep tests will not detect other bacteria that can cause tonsillitis that deserve antibiotic treatment. For example, severe and chronic cases of tonsillitis or tonsillar abscess may be culture negative. Similarly, negative cultures are seen with diphtheria. Infections from sexual contacts will also escape detection by strep culture tests. Healthy tonsils do not remain infected but frequent sore throats from tonsillitis suggest the infection is chronic and tonsillectomy should be considered.

Infections in the nose and sinuses also can cause sore throats because mucus from the nose drains down into the throat and carries the infection with it. The most dangerous throat infection is epiglottitis, caused by bacteria that infect a portion of the larynx (voice box) and cause swelling that narrows the airway. This infection is an emergency condition that requires prompt medical attention. This is suspected when swallowing is extremely painful (causing drooling), when speech is muffled, and when breathing becomes difficult. An Xray can be done to rule this out.

Allergy: The same pollens and molds that irritate the nose when they are inhaled also may irritate the throat. Cat and dog dander and house dust are common causes of sore throats for people with allergies to them.

Irritation: During the cold winter months, dry heat may create a recurring, mild sore throat with a parched feeling, especially in the mornings. This often responds to humidification of bedroom air and increased liquid intake. Patients with a chronic stuffy nose causing mouth breathing, also suffer with a dry throat. They need examination and treatment of the nose. Pollutants and chemicals in the air can irritate the nose and throat, but the most common air pollutant is tobacco smoke. Other irritants include smokeless tobacco, alcoholic beverages, and spicy foods. A person who strains his voice (yelling at a sports event) gets a sore throat not only from muscle strain but also from the rough treatment of his throat mucus membranes.

Reflux: An occasional cause of sore throat is regurgitation of stomach acid up into the back of the throat. To avoid reflux, tilt elevate your bedframe so that the head is 4-6 inches higher than the foot of the bed. You might find antacids helpful. You should also avoid eating within three hours of bedtime, and eliminate caffeine and alcohol. If these tips fail, see your doctor.

Tumors: Tumors of the throat, tongue, and larynx (voice box) are usually associated with long-term use of tobacco and alcohol. Sore throat, difficulty swallowing, and pain radiating to the ear can be symptoms of such a tumor. Other important symptoms include hoarseness, a lump in the neck, unexplained weight loss, and spitting up blood.

When should I take antibiotics?

Antibiotics are drugs that kill bacteria but do not cure viral infections. When an antibiotic is prescribed, it should be taken as the physician directs for the full course so that infection is eliminated and not simply suppressed. Some children will experience recurrent infection despite antibiotic treatment.

Should other family members be treated or cultured?

When a strep test is positive, family members should practice good sanitary habits—avoid close physical contact, sharing of napkins, towels, and utensils. However, frequent handwashing is the most important thing you can do to prevent the spread of communicative diseases.

What if my throat culture is negative?

A strep culture tests only for the presence of streptococcal infections. Many other infections, both bacterial and viral, will yield negative culture results. Therefore, when your culture is negative, your physician will base his decision for treatment on the severity of your symptoms and the appearance of your throat on examination.

How Can I Treat My Sore Throat?


  • Increase your liquid intake. Warm tea with honey is a favorite home remedy.
  • Use a humidifier in your bedroom.
  • Gargle with warm salt water several times daily: 1 tsp salt in 1 cup water.
  • Take mild pain relievers such as acetaminophen (Tylenol) or ibuprofen (Advil).

When Should I See a Doctor?

Whenever a sore throat is severe, persists longer than the usual 5-7 day duration of a cold or flu, and is not associated with an avoidable allergy or irritation, you should seek medical attention. The following signs and symptoms should alert you to see your physician:

  • Severe and prolonged sore throat
  • Difficulty breathing
  • Difficulty swallowing
  • Difficulty opening the mouth
  • Joint pain
  • Earache
  • Rash
  • Fever (over 101.5)
  • Blood in saliva or phlegm
  • Frequently recurring sore throat
  • Lump in neck
  • Hoarseness lasting over two weeks