A peritonsillar abscess, known historically as quinsy, is a localized collection of pus between the palatine tonsil capsule and the superior pharyngeal constrictor muscle, most often caused by spread of bacterial tonsillitis into the surrounding soft tissue. It is the most common deep-neck-space infection in adolescents and young adults, with an incidence of roughly 30-37 cases per 100,000 person-years in industrialized countries.
Peritonsillar abscess (ICD-10: J36) is a suppurative collection in the peritonsillar space — the loose connective-tissue plane between the lateral aspect of the palatine tonsil capsule and the superior pharyngeal constrictor muscle. The infection most often arises as a complication of acute exudative tonsillitis when bacterial spread crosses the tonsillar capsule, but can also originate from the supratonsillar minor salivary glands (Weber glands), explaining cases without preceding tonsillitis. Microbiology is mixed: predominant organisms are Streptococcus pyogenes (group A streptococcus, in 30-50%), Streptococcus anginosus group, Fusobacterium necrophorum, Prevotella, Peptostreptococcus, and Staphylococcus aureus including MRSA. The abscess is supero-lateral to the tonsil in 90% of cases, but inferior pole abscesses occur.
The key symptoms of Peritonsillar Abscess are: Severe one-sided sore throat that worsens progressively over 2-4 days and is poorly relieved by simple analgesia., Painful and limited mouth opening (trismus) with an interincisor distance often under 2 cm — a hallmark feature., Muffled hot-potato voice from soft palate swelling, distinguishable from the hoarseness of laryngitis., Drooling and pooling of saliva because swallowing is too painful to maintain, with weight loss and dehydration over 24-48 hours., Ipsilateral referred earache (otalgia) from glossopharyngeal nerve involvement., Fever, usually 38.5-40 °C, with rigors, myalgia, and malaise., Swollen, tender cervical lymphadenopathy, especially in the jugulodigastric chain on the affected side..
Diagnosis is largely clinical. The combination of severe unilateral sore throat, trismus, hot-potato voice, drooling, fever, and a bulging soft palate with contralateral uvular deviation is highly specific. Examination begins with vital signs (fever, tachycardia, blood pressure), assessment of mouth opening (interincisor distance), airway patency, and inspection of the oropharynx using a tongue depressor and headlight. Trismus often limits direct visualization; intraoral ultrasound at the bedside, transcutaneous ultrasound, or contrast-enhanced CT of the neck differentiates abscess from cellulitis when examination is non-diagnostic or deep-neck-space extension is suspected. Bloodwork shows leukocytosis with neutrophilia, raised C-reactive protein, and sometimes electrolyte derangement from poor fluid intake. Throat swab for rapid streptococcal antigen and culture is taken when feasible. Diagnostic and therapeutic needle aspiration with a 16-18G needle, after topical lignocaine spray, confirms the diagnosis by aspirating pus and decompresses the abscess in a single step. Aspirate is sent for Gram stain, aerobic and anaerobic culture. CT imaging is reserved for patients in whom direct examination is impossible (severe trismus), bilateral abscess is suspected, the abscess fails to resolve, deep-neck extension is suspected, or recurrent presentation. Lemierre syndrome should be considered when high fever and rigors persist after drainage; CT of the neck with contrast and blood cultures identify internal jugular vein thrombophlebitis. Differential diagnosis includes peritonsillar cellulitis, infectious mononucleosis with massive tonsillar swelling, parapharyngeal abscess, dental abscess, and tonsillar lymphoma in patients with persistent unilateral tonsil enlargement.
Outcomes are excellent with prompt drainage and appropriate antibiotics: more than 90% of patients are afebrile and tolerating oral intake within 48 hours of treatment, and most are discharged on day 2-3. Recurrence rates after initial successful drainage are 9-22% in long-term follow-up; risk is highest in patients with a history of recurrent tonsillitis, smokers, and patients under 30 years old. Interval or quinsy tonsillectomy prevents recurrence in over 95% of these patients. Complications include parapharyngeal or retropharyngeal abscess, mediastinitis, jugular vein thrombophlebitis (Lemierre syndrome), airway obstruction, aspiration pneumonia, and rarely carotid blowout. Mortality is under 0.5% in high-income healthcare systems but rises significantly when diagnosis is delayed or in immunocompromised patients. Untreated infection can progress to airway compromise or descending necrotising mediastinitis with mortality of 15-40% even with modern care.
An otolaryngologist (ENT) is the appropriate specialist for definitive drainage, airway assessment, and decisions about quinsy versus interval tonsillectomy. Emergency referral is essential when there is severe trismus, drooling, stridor, suspicion of deep-neck infection, or failure to improve within 24 hours of antibiotic therapy.
Find specialists →Pain and trismus improve markedly within 24-48 hours of drainage. Most patients return to school or work after 5-7 days. Antibiotics are completed over 10 days. Full energy and appetite return over 2-3 weeks. Interval tonsillectomy, if planned, is scheduled 4-6 weeks after the acute episode when inflammation has fully resolved.
Bed rest during acute illness; light walking once afebrile. Avoid strenuous exercise and contact sport until at least one week after discharge to reduce the risk of post-drainage bleeding and to allow full hydration recovery.
Choose a centre with 24-hour ENT cover, anaesthetic support for shared-airway management, and access to contrast-enhanced CT. Ask about success rates of needle aspiration versus incision and drainage, and policy on interval tonsillectomy after recurrence.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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