Peritonsillar Abscess

Updated: Jul 25, 2022
Author: Benoit J Gosselin, MD, FRCSC; Chief Editor: John Geibel, MD, MSc, DSc, AGAF 



Peritonsillar abscess (PTA) was first described as early as the 14th century; however, it is only since the advent of antibiotics in the 20th century that the condition has been described more extensively. A PTA is a localized accumulation of pus in the peritonsillar tissues that forms as a result of suppurative tonsillitis. An alternative explanation is that a PTA is an abscess formed in a group of salivary glands in the supratonsillar fossa, known as Weber glands.

The nidus of accumulation is located between the capsule of the palatine tonsils and the constrictor muscles of the pharynx. The anterior and posterior pillars, torus tubarius (superior), and pyriform sinus (inferior) form the boundaries of this potential peritonsillar space. Because this area is composed of loose connective tissue, severe infection may rapidly lead to formation of purulent material. Progressive inflammation and suppuration may extend to directly involve the soft palate, the lateral wall of the pharynx, and, occasionally, the base of the tongue.

PTA is usually a complication of an acute tonsillitis. Inflammatory edema may lead to significant difficulty in swallowing. Dehydration frequently occurs secondary to the patient's avoidance of painful ingestion of food and liquids. Expansion of the abscess may lead to extension of the inflammation into adjacent fascial compartments of the head and neck, potentially resulting in airway obstruction.

For patient education resources, see the Ear, Nose, and Throat Center, as well as Peritonsillar Abscess, Tonsillitis, and Antibiotics.


The palatine tonsils are paired lymphoid organs found between the palatoglossal and palatopharyngeal folds of the oropharynx. They are surrounded by a thin capsule that separates the tonsil from the superior and middle constrictor muscles.

The anterior and posterior pillars form the front and back limits of the peritonsillar space. Superiorly, this potential space is related to the torus tubarius, while inferiorly it is bounded by the pyriform sinus. Composed solely of loose connective tissue, a severe infection may rapidly result in pus formation. The inflammation and suppurative process may extend to involve the soft palate, the lateral wall of the pharynx, and, occasionally, the base of the tongue.

The tonsillar fossa has a rich network of lymphatic vessels leading to the parapharyngeal space and the upper cervical lymph nodes, which explains the pattern of adenopathy observed clinically. Ipsilateral upper cervical lymphadenopathy is the result of the spread of infection to the regional lymphatics. Occasionally, the severity of the suppurative process may lead to a cervical abscess, especially in very fulminant or rapidly progressive cases.


The pathophysiology of PTA is unknown. The most widely accepted theory involves the progression of an episode of exudative tonsillitis first into peritonsillitis and then into frank abscess formation. Extension of the inflammatory process may occur in both treated and untreated populations. PTA also has been documented to arise de novo without any prior history of recurrent or chronic tonsillitis. A PTA also can be the presentation of an Epstein-Barr virus (ie, mononucleosis) infection.

Another theory proposes the origin of PTA in Weber glands. These minor salivary glands are found in the peritonsillar space and are thought to help in clearing debris from the tonsils. Should obstruction as a result of scarring from infection occur, tissue necrosis and abscess formation result, leading to PTA.


Any of the microorganisms that cause acute or chronic tonsillitis may be the cause of a PTA. Most commonly, aerobic and anaerobic gram-positive organisms are identified by means of culture.

Cultures of affected patients reveal group A beta-hemolytic streptococci as most prevalent. Next most commonly, staphylococci, pneumococci, and Haemophilus organisms are found. Finally, other microorganisms that can be cultured include lactobacilli, filamentous forms such as Actinomyces species, micrococci, Neisseria species, diphtheroids, Bacteroides species, and nonsporulating bacteria. Some evidence indicates that anaerobic bacteria frequently cause these infections.[1]


The incidence of PTA in the United States is about 30 cases per 100,000 people per year, representing about 45,000 new cases each year. No accurate data are available internationally.

Although tonsillitis is a disease of childhood, only one third of PTA cases are found in this age group. The age of patients with the condition is variable, ranging from 1 to 76 years, with the highest incidence in persons aged 15-35 years. No sexual or racial predilection has been established.

In a retrospective cohort study of 427 patients with PTA, Marom et al investigated how the characteristics of PTA may have changed over time.[2] The results led the authors to conclude that PTA currently tends to affect an older population than it once did, that its course in older individuals has become longer and worse, and that smoking may be a predisposing factor in its development.

A study of 685 patients by Kordeluk et al looked at the relation between peritonsillar cellulitis and abscess and outbreaks of acute tonsillitis.[3] The authors found peaks with seasonal variation for presentations with acute tonsillitis but no association with PTA, which occurred at similar rates throughout the calendar year.

A study from Spain found that the institution of protective measures as a result of the COVID-19 pandemic led to a 43% reduction in the incidence of peritonsillar infection from the 2017-2019 period to 2020; however, the cases that did occur tended to have a longer recovery period, and there were more PTAs.[4]

A study from the United States did not find the pandemic to have a significant effect on the incidence of PTA in pediatric otolaryngology practice.[5]


Most patients treated with antibiotics and adequate drainage of their abscess cavity recover within a few days. A small number present with another abscess later, requiring tonsillectomy. If patients continue to report recurring or chronic sore throats after proper incision and drainage (I&D), a tonsillectomy may be indicated.

In a nationwide retrospective cohort study from Taiwan, Wang et al found that the risk of PTA recurrence rose with higher degrees of previous tonsillitis in patients of all ages, whereas such a rise was associated with management by needle aspiration only in pediatric patients.[6] The risk of PTA recurrence was highest in patients who were younger than 30 years and had experienced more than five prior episodes of tonsillitis.




Patients with a peritonsillar abscess (PTA) typically present with a history of acute pharyngitis accompanied by tonsillitis and worsening unilateral pharyngeal discomfort. Patients also may experience malaise, fatigue, and headaches. They often present with a fever and asymmetric throat fullness. Associated halitosis, odynophagia, dysphagia, and a "hot potato–sounding" voice occur.

Many patients present with ipsilateral referred otalgia with swallowing. Trismus (ie, a limitation in the ability to open the oral cavity) of varying severity is present in all cases, reflecting lateral pharyngeal wall and pterygoid musculature inflammation. Because of lymphadenopathy and cervical muscle inflammation, patients often experience neck pain and even a limitation in neck mobility. Clinicians need to be alerted to the diagnosis of a PTA in patients who have pharyngeal symptoms that persist despite an adequate antibiotic regimen.

As the degree of inflammation and infection proceeds, symptoms include progression in the floor of the mouth, the parapharyngeal space, and the prevertebral space. Extension in the floor of the mouth is worrisome because of airway obstruction; the clinician must be aware of an eventual airway emergency.

Physical Examination

The presentation may range from acute tonsillitis with unilateral pharyngeal asymmetry to dehydration and sepsis. Most patients have severe pain. Examination of the oral cavity reveals marked erythema, asymmetry of the soft palate, tonsillar exudation, and contralateral displacement of the uvula (see the image below).

Right peritonsillar abscess. Soft palate, which is Right peritonsillar abscess. Soft palate, which is erythematous and edematous, is displaced anteriorly. Patient has "hot potato–sounding" voice.

Indications for considering the diagnosis of a PTA include the following:

  • Unilateral swelling of the peritonsillar area
  • Unilateral swelling of the soft palate, with anterior displacement of the ipsilateral tonsil
  • Nonresolution of acute tonsillitis, with persistent unilateral tonsillar enlargement

In a retrospective study from the University of Ottawa, Kilty and Gaboury reported that in 50 adults with PTA, clinical signs that had a significant association with the lesion included uvular deviation, trismus, and inferior displacement of the superior pole of the tonsil on the affected side.[7]

A PTA ordinarily is unilateral and located at the superior pole of the affected tonsil, in the supratonsillar fossa. At the level of the supratonsillar fold, the mucosa may appear pale and even show a small pimple. Palpation of the soft palate often reveals an area of fluctuance. Flexible nasopharyngoscopy and laryngoscopy are recommended in patients experiencing airway distress. The laryngoscopy is key to ruling out epiglottitis and supraglottitis, as well as vocal cord pathology.

The degree of trismus depends on the extent of lateral pharyngeal space inflammation. If it is very marked, one should be concerned about possible lateral pharyngeal space cellulitis. The finding of tender ipsilateral cervical lymphadenopathy involving single or multiple nodes is not uncommon. The affected lymph nodes may be quite firm. In presentations with significant nodal inflammation, the patient may experience torticollis and limitation of neck mobility. A more detailed evaluation is essential if suspicion of an accompanying cervical abscess exists.


Numerous clinical complications may occur if the diagnosis of a PTA is missed or delayed. The severity of the complications depends on the rapidity of progression of the illness, as well as the characteristics of the affected fascial spaces. Early management and intervention are important.

The fascial spaces of the neck are interconnected. Once inflammation exceeds the limits of the peritonsillar space, involvement of the masticator space (with increasing degrees of trismus) occurs. Extension may progress to the submandibular and sublingual spaces within the floor of the mouth (Ludwig angina). At this point, emergency airway control through intubation or tracheotomy is indicated to obviate obstruction from swelling of the base of the tongue. In severe cases, death may occur.

Other well-reported complications due to continued progression of the infection may lead to a parapharyngeal abscess, descending necrotizing mediastinitis, Lemierre syndrome, and internal carotid artery pseudoaneurysm.[8, 9, 10, 11]



Laboratory Studies

Patients presenting with peritonsillar abscesses (PTAs) often are septic in appearance and may demonstrate varying degrees of dehydration due to abstention from oral intake. Assessment of these two entities should involve the collection of blood for a complete blood count, electrolyte level measurement, and blood cultures.

In patients presenting with tonsillitis and bilateral cervical lymphadenopathy, a monospot test (heterophile antibodies) should be considered. If the test results are positive, the patient requires careful evaluation of hepatosplenomegaly. Liver function tests should be considered in patients with hepatomegaly.

To facilitate the identification of infectious organisms, a throat swab and culture are to be considered. The results may help the clinician select the most appropriate antibiotic once the organism is identified, limiting the risk of antibiotic resistance.

Imaging Studies

Imaging may be particularly useful in cases where an attempt at incision and drainage (I&D) has failed or where worsening edema in a treated peritonsillar cellulitis is noted. In certain cases, the abscess may be within the tonsil itself or partially hidden (ie, inferior or posterior) by the tonsil.

Plain radiography

Lateral soft tissue views of the nasopharynx and oropharynx may help the clinician rule out a retropharyngeal abscess. In the anteroposterior view, the films reveal distortion of soft tissues but are not useful in localizing an abscess.

Computed tomography

In selected clinical settings and in very young patients, radiologic evaluation may be performed by means of computed tomography (CT) of the oral cavity and neck using intravenous (IV) contrast enhancement.

Common findings are the presence of a hypodense fluid collection in the apex of the affected tonsil, with peripheral rim enhancement. Other findings may include an asymmetric enlargement of the tonsils and surrounding fossa. Further delineation of cervical adenopathy is facilitated, as is the identification of a possible intranodal fluid collection, which indicates a cervical abscess and helps in the planning of surgical management.


Intraoral ultrasonography has been proposed as an imaging modality.[12] It is a simple, well-tolerated, noninvasive technique that can help distinguish between cellulitis and the presence of an abscess. Intraoral ultrasonography also allows the option of a more directed aspiration of the tonsillar fossa before definitive surgical drainage is attempted. One study has shown that this approach is also clinically useful in the evaluation of patients presenting in the emergency department.

Diagnostic Procedures

Needle aspiration of the abscess site (see the image below) may be performed just before the drainage procedure is attempted. It allows identification of the location of the abscess in the peritonsillar space.

Pus is aspirated from right peritonsillar abscess Pus is aspirated from right peritonsillar abscess through large-bore needle. Additional incision will be made to drain any other pus pockets.

The aspiration site is anesthetized by using lidocaine with epinephrine, and a large-bore (16- to 18-gauge) needle is mounted on a 10-mL syringe. Infiltration is the method of choice for administering local anesthesia for aspiration and incision of peritonsillar abscesses. The needle is passed through the anesthetized mucosa, where aspiration of the site is performed. Aspiration of purulent material is diagnostic, and the material may be sent for culture.



Approach Considerations

In cases of peritonsillar abscess (PTA), when incision and drainage (I&D) is performed, it leads to immediate improvement of the patient's symptoms. Needle aspiration may be used as a diagnostic modality and as a therapeutic one, because it allows the accurate localization of the abscess cavity. The aspirated fluid may be sent for culture, and in some cases, I&D may not be necessary. If patients continue to report recurring and/or chronic sore throats after proper I&D, a tonsillectomy may be indicated.

Intraoral drainage has a high rate of success, with low morbidity and a low rate of recurrence. Normally, unless the patient presents with recurrent tonsillitis or recurrent PTA, tonsillectomy is not indicated; however, in situations where the abscess is located in an area difficult to access, a tonsillectomy may be the only way to drain the abscess.

Medical Therapy

Patients with PTAs who are dehydrated require intravenous (IV) fluid administration until the inflammation resolves and they are able to resume adequate oral fluid intake.

Antipyretics and analgesics are used to alleviate fever and discomfort. Oral and parenteral analgesics are an integral part of the management and allow the patient to resume oral intake. Often, the pain relief from I&D is so significant that the patient is able to resume oral intake with nonnarcotic analgesics.

Antibiotic therapy should begin after cultures are obtained from the abscess. High-dose IV penicillin remains a good choice for empiric treatment of PTA. Alternatively, because of the polymicrobial nature of cultured pus, agents that treat copathogens and resist beta-lactamases also have been recommended as a first choice. Cephalexin or another cephalosporin (with or without metronidazole) is likely the best initial option. Alternatives include the following:

  • Cefuroxime or cefpodoxime (with or without metronidazole)
  • Clindamycin
  • Amoxicillin-clavulanate (if mononucleosis has been ruled out)

Oral antibiotics may be prescribed once the patient is able to tolerate oral intake; treatment should be continued for 7-10 days.

The use of steroids has been controversial. In a study by Ozbek, the addition of a single dose of IV dexamethasone to parenteral antibiotics significantly lessened the variables of hours hospitalized, throat pain, fever, and trismus in comparison with treatment involving only parenteral antibiotics.[13] In addition, the use of steroids in patients presenting with signs and symptoms of mononucleosis has not led to the formation of a PTA.

Surgical Therapy

Management of a patient with a suspected PTA should include a referral to an otolaryngologist or a surgeon with experience in the management of this entity. Early referral should be considered if the diagnosis is unclear and is indicated in patients who present with airway obstruction.

Preparation for surgery

Discussing the pathophysiology and indications for surgery with the patient is essential. Informed consent should be obtained from the patient or surrogate only after the potential complications have been carefully described.

In cases in which airway access may be compromised, an emergency consultation with the anesthesiologist is obtained, and the potential of airway obstruction is discussed. If necessary, the anesthesiologist may perform an intubation using a flexible bronchoscope with the patient in the semisupine position. A significant potential for airway obstruction exists if the patient's airway access is limited by significant trismus or by edema of the oropharyngeal structures.

Procedural details

There continues to be controversy regarding the relative merits of needle aspiration and I&D as definitive therapeutic modalities. With cooperative patients, procedures may be performed in an examination chair. The supratonsillar fold is anesthetized by either mucosalization or injection of a local anesthetic with epinephrine to reduce bleeding. If injection of a local anesthetic is performed, care should be taken to superficially infiltrate the overlying mucosa and surrounding soft palate.

Needle aspiration

Needle aspiration can be carried out in children as young as 7 years, especially if conscious sedation is used. Needle aspiration may be used both as a diagnostic and as a therapeutic modality because it allows accurate localization of the abscess cavity. The fluid aspirated may be sent for culture, and in some cases, needle aspiration may not have to be followed by I&D.

Incision and drainage

Intraoral I&D is performed by incising the mucosa overlying the abscess, usually located in the supratonsillar fold. Once the abscess is localized, blunt dissection is carried out to break loculations. The opening is left open to drain, and the patient is asked to gargle with a sodium chloride solution, allowing the accumulated material to exit the abscess cavity. Successful aspiration or drainage leads to immediate improvement of the patient's symptoms.

Other concerns

With very young or uncooperative patients or patients whose abscess is in an unusual location, the procedure is best performed under general anesthesia.

Immediate tonsillectomy as part of the management of a PTA also has been a subject of controversy. Many studies have shown the safety of a tonsillectomy in the setting of an acute abscess. Others have shown that immediate or delayed tonsillectomy may not be necessary because of the high rate of success and the low recurrence rate and morbidity associated with intraoral drainage. When the abscess is located in an area that is difficult to access, a tonsillectomy may be the only way to drain it.

A systematic review and meta-analysis by Tsikopoulos et al found no significant differences in clinical poutcomes between immediate and delayed tonsillectomy for PTA.[14]

Smoking is often more common among patients with peritonsillar abscess and is often associated with more complications.[15]

Postoperative Care

Because of the rapid alleviation of pain commonly achieved with surgical treatment, most patients may be discharged immediately after the procedure if they are able to tolerate oral intake of fluids and bleeding is not apparent. Some patients may require admission in the hospital setting for 24-48 hours or until oral intake is properly reestablished and pain is well controlled.

IV hydration is important because most patients present with significant fluid deficits. Continued use of antibiotics in the postoperative period is important as well. When the patient is able to take sufficient fluids by mouth, antibiotics may be administered orally for 7-10 days. Because of the level of discomfort from the ongoing inflammation, administration of oral analgesics is also helpful.


In patients treated with I&D, evaluating the patency of the opening is important. Premature closure before the cavity has become obliterated is possible, leading to reaccumulation of pus. This may warrant a second I&D procedure or a tonsillectomy.

Limiting the drainage incision to the mucosa of the soft palate and using blunt dissection within the cavity are important for preventing serious bleeding. The terminal branches of the external carotid artery lie on the posterior aspect of the tonsillar fossa and can be injured easily, particularly in children, in whom they are relatively superficial.

Bleeding is a potential complication if branches of the external carotid artery are injured or if the external carotid artery itself is injured. The bleeding may occur intraoperatively or in the early postoperative period.

Intraoperative hemorrhage is an emergency and results from direct injury to the external carotid artery or terminal branches thereof. Once the patient is stabilized hemodynamically, the tonsillar fossa is reevaluated. The ipsilateral neck also should be prepared and draped in a sterile fashion to provide access to the proximal external carotid artery. If the hemorrhage is controlled intraorally, the patient's continued stabilization is pursued.[16]

If the bleeding appears to be too brisk, and it is not controlled by careful intraoral source identification, an ipsilateral cervicotomy is performed, as follows.

The sternocleidomastoid is retracted laterally, and the carotid sheath contents are identified. The internal jugular vein, the vagus nerve, and the carotid arteries (common, external, and internal) are identified. A vascular loop is applied around the external carotid artery to assess temporization of bleeding. The external carotid artery is dissected superiorly, with careful attention to preserving the external laryngeal, the ansa hypoglossi, and the hypoglossal nerves. Ligation of the external carotid artery may prove necessary.

The general approach to postoperative hemorrhage similarly is directed to the identification of the source of bleeding. The patient is brought to the operating room, and the same procedure as described above is followed.

Long-Term Monitoring

Patients are seen routinely in follow-up in the office setting. Elements to consider at that time are reduction of the amount of pain, defervescence, and ability to comfortably resume oral intake.

During the examination, it is important to inspect the drainage site carefully and to rule out reaccumulation of pus. Assessment should include checking for improvement in tonsillar appearance, inflammation, and the resolution of cervical lymphadenopathy. In general, unless the patient presents with a history of recurring tonsillitis or recurrent PTA, tonsillectomy is not indicated.


Questions & Answers


What is peritonsillar abscess (PTA)?

What is the anatomy relevant to peritonsillar abscess (PTA)?

What is the pathophysiology of peritonsillar abscess (PTA)?

What causes peritonsillar abscess (PTA)?

What is the incidence of peritonsillar abscess (PTA)?

What is the prognosis of peritonsillar abscess (PTA)?


Which clinical history findings are characteristic of peritonsillar abscess (PTA)?

Which physical findings are characteristic of peritonsillar abscess (PTA)?

What are complications of peritonsillar abscess (PTA)?


What is the role of lab tests in the diagnosis of peritonsillar abscess (PTA)?

What is the role of imaging studies in the diagnosis of peritonsillar abscess (PTA)?

What is the role of plain radiography in the diagnosis of peritonsillar abscess (PTA)?

What is the role of CT scanning in the diagnosis of peritonsillar abscess (PTA)?

What is the role of ultrasonography in the diagnosis of peritonsillar abscess (PTA)?

What is the role of needle aspiration in the workup of peritonsillar abscess (PTA)?


How is a peritonsillar abscess (PTA) treated?

What is the focus of medical therapy for the treatment for peritonsillar abscess (PTA)?

What is the role of antibiotic therapy in the treatment of peritonsillar abscess (PTA)?

What is the role of steroids in the treatment of peritonsillar abscess (PTA)?

What is the role of needle aspiration in the surgical treatment of peritonsillar abscess (PTA)?

What is the role of incision and drainage in the surgical treatment of peritonsillar abscess (PTA)?

When is consultation with an otolaryngologist or surgeon indicated for the treatment for peritonsillar abscess (PTA)?

What is included in preprocedural care for patients with peritonsillar abscess (PTA)?

How is the patient prepared for surgery for peritonsillar abscess (PTA)?

When is general anesthesia indicated for the surgical treatment for peritonsillar abscess (PTA)?

What is the role of tonsillectomy in the treatment of peritonsillar abscess (PTA)?

Which factor increases the risk for surgical complications in the treatment of peritonsillar abscess (PTA)?

What is included in postoperative care following surgical treatment of peritonsillar abscess (PTA)?

What are possible complications of surgery for peritonsillar abscess (PTA)?

What is included in long-term monitoring following treatment of peritonsillar abscess (PTA)?