Painful swallowing localized to only one side of the throat (unilateral odynophagia) is a distinct symptom that narrows the potential list of causes compared to generalized throat pain. The throat is a complex structure lined with sensitive mucosal tissue, meaning pain can arise from many different sources. When discomfort is confined to the right side during swallowing, it often suggests a highly localized issue, such as inflammation or injury. This unilateral presentation points toward a concentrated problem rather than a systemic infection that typically affects both sides equally.
Common Infectious Causes
The most frequent causes of one-sided throat pain are infections where the inflammatory response is concentrated on one side. Tonsillitis, an inflammation of the tonsils typically caused by viruses or bacteria, often presents with pain that is noticeably worse on one side if that tonsil is more severely infected. This localized swelling makes swallowing difficult. Viral pharyngitis, including illnesses like the common cold or flu, can also lead to soreness on one side, sometimes because postnasal drip has irritated one specific area more intensely while sleeping.
Mononucleosis (mono) is a viral infection that causes significant, often asymmetrical, swelling of the tonsils and lymph nodes. The Epstein-Barr virus responsible for mono can lead to substantial inflammation, making the right side feel much more painful if the lymphatic tissue there is reacting aggressively. Streptococcal pharyngitis (strep throat) can also manifest with one-sided pain, despite usually presenting as a generalized infection.
When these infections are severe, they may progress into a peritonsillar abscess—a collection of pus that forms behind one of the tonsils. This localized, severe bacterial infection causes intense, unilateral pain and swelling. It is a medical emergency due to its potential to obstruct the airway.
Non-Infectious Irritation and Structural Issues
Unilateral throat pain can stem from physical, chemical, or structural problems rather than a bacterial or viral pathogen. Gastroesophageal Reflux Disease (GERD) or Laryngopharyngeal Reflux (LPR) causes irritation when stomach acid backs up into the esophagus and throat. If a person sleeps predominantly on the right side, the acid may pool or irritate the tissue on that side, resulting in morning pain that feels distinctly one-sided.
Referred pain originating from the jaw or mouth is another common non-infectious cause, traveling along shared nerve pathways to feel like throat pain. For example, an abscessed or impacted wisdom tooth on the right side can cause throbbing pain that radiates into the throat, mimicking a tonsil infection. Similarly, dysfunction of the temporomandibular joint (TMJ) on the right side can cause muscle tension and nerve irritation perceived as one-sided throat soreness when swallowing.
Lymph nodes, which filter the immune system, can be the sole source of discomfort when they swell while fighting a localized infection. Even a minor scratch or canker sore on the right side of the mouth can cause the nearby lymph node to swell, creating pressure and pain when the throat muscles contract during swallowing. Mechanical irritation, such as a scratch from a sharp piece of food, can also temporarily damage the delicate mucosal lining and cause pain.
Understanding Urgent Symptoms
While most cases of one-sided throat pain resolve on their own, certain accompanying symptoms require immediate medical attention. The inability to swallow saliva (drooling) suggests a severe blockage or intense pain that may signal a rapidly developing abscess or airway compromise. Difficulty breathing, especially if accompanied by a high-pitched sound during inhalation, indicates the upper airway is becoming restricted.
Severe pain that makes it difficult to open the mouth fully (trismus) is frequently associated with a peritonsillar abscess and warrants prompt evaluation. A high fever (over 103°F) or the rapid onset of significant swelling in the neck should also be treated urgently. If the localized pain lasts longer than five to seven days without improvement, or if the pain is chronic and accompanied by unexplained weight loss or a persistent lump, consult a healthcare provider for a thorough examination.