Antibiotics After Hemorrhoidectomy: Not Routinely Recommended
Routine antibiotic prophylaxis is not indicated after hemorrhoidectomy, and postoperative antibiotics should not be prescribed beyond 24 hours, as there is no evidence they reduce surgical site infections and their use increases antimicrobial resistance and complications. 1, 2
Preoperative Prophylaxis Only
A single preoperative dose of cefazolin 1-2g IV administered 30-60 minutes before incision is adequate for hemorrhoidectomy, with all prophylactic antibiotics discontinued within 24 hours after surgery 1, 3
For patients with beta-lactam allergies, use clindamycin 900mg IV plus gentamicin 5mg/kg as a single dose, or vancomycin 30mg/kg infused over 120 minutes 4, 5
Re-dosing cefazolin 1g IV is only necessary if the procedure exceeds 4 hours (two half-lives) or blood loss exceeds 1.5 liters 4
Evidence Against Routine Postoperative Antibiotics
Multiple high-quality studies demonstrate that postoperative surgical site infection after hemorrhoidectomy is exceedingly rare (1.4% incidence), and antibiotic prophylaxis does not reduce this already low rate 2
A 2014 randomized controlled trial of 852 patients found no difference in infection rates between those receiving antibiotics (41.3%) versus no antibiotics (58.7%), with p=0.25 2
Two separate RCTs (2014 and 2024) comparing prophylactic antibiotics versus no antibiotics in Milligan-Morgan hemorrhoidectomy found no difference in pain scores, wound healing, infection rates, or inflammatory markers 6, 7
The WHO and CDC explicitly state there is no evidence supporting postoperative antibiotic prophylaxis beyond 24 hours for clean-contaminated procedures, and extending antibiotics increases antimicrobial resistance, Clostridium difficile infection, hypersensitivity reactions, and renal failure 4, 1
When Therapeutic (Not Prophylactic) Antibiotics Are Indicated
Antibiotics should only be initiated postoperatively if true infection develops, defined by: 1
- Fever with systemic inflammatory response syndrome (SIRS)
- Purulent drainage from the surgical site
- Erythema greater than 5 cm from the incision with induration
- Deep incisional surgical site infection
- Severe pain and swelling beyond expected postoperative course
If infection develops, empiric coverage should target skin flora and anaerobes with ampicillin-sulbactam OR cefazolin plus metronidazole 1
Special Populations
Immunocompromised Patients
A 2025 Mayo Clinic study of 55 immunocompromised patients (on chronic corticosteroids, methotrexate, or post-transplant immunosuppression) undergoing 68 hemorrhoidal procedures found only 3 cases (5.5%) of postoperative cellulitis and zero cases of pelvic sepsis 8
Even in immunocompromised patients, routine postoperative antibiotics are not indicated unless signs of infection develop 1, 8
Antibiotics are only indicated if SIRS develops, deep incisional SSI occurs, or the patient has severe neutropenia (ANC <500) 1
Metronidazole for Pain Control (Not Infection Prevention)
Metronidazole has demonstrated efficacy specifically for postoperative pain reduction after hemorrhoidectomy and may be prescribed for this indication, not for infection prophylaxis 1
This represents a therapeutic use for pain management, distinct from antimicrobial prophylaxis
Common Clinical Pitfall
The presence of an open wound or perianal location does not justify extending antibiotics beyond 24 hours 4, 1. Hemorrhoidectomy is classified as a clean-contaminated procedure, and the contamination occurs intraoperatively—not postoperatively—making extended prophylaxis ineffective 9, 1