Mann 1999.

Methods	Single‐centre, randomised, double‐blind, placebo‐controlled study conducted in USA Grading of quality: Randomisation = C Blinding = A (author correspondence confirmed dispensation of placebo as a capsule, but could not confirm if it was exactly identical to amoxicillin capsule; we believe this was adequate double‐blinding) Intention‐to‐treat analysis = C Follow‐up = D Overall quality grading = C
Participants	51 adults 18 years and above undergoing tonsillectomy for tonsillitis, peritonsillar abscess or tonsillithiasis were enrolled and randomised into 4 arms: systemic antibiotic, placebo and 2 different topical antibiotics. The 2 arms that studied topical antibiotics were unsuitable for analysis and therefore excluded, leaving 18 patients in the first 2 arms (8 in antibiotic and 10 in control arms) who completed the study. Study and control groups well‐matched with regard to age and sex. Exclusion criteria: significant medical conditions (i.e. diabetes, chronic lung disease, bleeding disorders), antibiotic administered within 1 week preoperatively, medical condition requiring perioperative antibiotic therapy, or allergy to antibiotic studied
Interventions	Amoxicillin tds oral for 7 days
Outcomes	Primary outcome: pain (scale 1 to 100; 0 = no pain, 100 = severe pain) Period of observation: 5 days
Notes	Anaesthetic technique not mentioned as controlled. Surgical technique was quasi‐controlled: the tonsillectomy technique is not mentioned, and instead only the haemostatic method (electrocautery) is mentioned. Follow‐up: 36 (71%) of 51 patients in the whole study completed follow‐up. Authors stated that the numbers lost to follow‐up were evenly distributed in the 4 arms, but exact follow‐up rates in the systemic antibiotic and placebo arms not available.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear