Background Peritonsillar abscess (PTA) is the most common deep neck infection, occurring as a consequence of bacterial acute tonsillitis or as a result of infection of the Weber glands, with frequent and life-threatening complications. Aim To investigate several factors associated with complications and worse prognosis, such as defining the method of surgical drainage and treatment of a PTA which remains an area of controversy in the literature Methods The purpose of this retrospective study is to examine the epidemiological, clinical, and laboratory findings of 601 adult patients and to discuss them along with their treatment plan. Results Pharyngalgia was the most common reported symptom, followed by trismus, odynophagia, fever, hot potato voice, malaise, and cervical lymphadenopathy. Sixty-eight patients developed complications. Streptococcus species were the most common pathogens. A statistically significant difference was found in days of hospitalization, WBC and CRP levels, age, and the pre-existing systemic diseases between patients with and without complications. A comparison of patients treated with intravenous and oral antibiotics revealed no statistically significant difference. Conclusion Οver 10% of PTA cases may develop complications, the most common of which is extension into deep neck spaces. Comorbid conditions increase the risk of complications. Despite the wide range of treatment strategies, incision and drainage remain the cornerstone of surgical treatment. In patients with no comorbidities, intravenous antibiotics appear to have no advantage over oral antibiotics.