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Are Antibiotics a Treatment Option for Low Back Pain?

Ask the Expert for March 2014

Question: Are antibiotics a treatment option for low back pain?

Answer: Antibiotics can be used for durations up to 90 days in the treatment of postoperative discitis.1-3 This has led to the study of antibiotics as a potential treatment for low back pain, specifically 2 small studies have evaluated the use of amoxicillin-clavulanate in treating low back pain.4-5 The results of these studies has raised the possibility that bacterial infection may play a role in low back pain with Modic changes.

In the first study, a randomized controlled trial, the investigators evaluated the use of amoxicillin/clavulanate in patients with chronic low back pain after a disc herniation with Modic type 1 changes.4 During the study, 162 patients were assigned to 100 days of 1 of 3 treatments: amoxicillin-clavulanate
(500 mg/125 mg) 1 tablet 3 times daily, 2 tablets 3 times daily, or placebo. Additionally, “mild” analgesics were permitted at the physicians’ discretion. The primary outcomes were based on a self-reported questionnaire performed at baseline, 100 days, and 1 year. The antibiotic group had a change in the median Ronald Morris Disability Questionnaire (RMDQ) score from 15 at baseline to 11.5 at 100 days and 7 at 1-year follow up, which was ≥30% reduction required to establish clinical improvement. The placebo group had a median RMDQ baseline score reduction from 15 to 14. Due to a lack of power, no comparison could be made between the different dosage regimens. A large number of adverse events (especially diarrhea and gastrointestinal complaints) were observed in the antibiotic groups (65%) compared with the placebo group (23%).

In the second study, an uncontrolled trial with 29 patients, investigators evaluated the use of antibiotics as an option for treating low back pain associated with Modic changes type 1.5 Patients were assigned to take amoxicillin-clavulanate (500 mg/125 mg) 1 tablet 3 times daily for 90 days. Clinically improved RMDQ scores (≥30% improvement) occurred in 18 (62%) patients at the end of treatment and at 11-months follow up. No improvement was seen in 10 patients (34.5%) at end of treatment and 9 (31%) patients at 11-month follow up. The RMDQ was clinically worse, as defined by ≥30% worsening on RMDQ, in 1 (3.5%) and 2 (7%) patients at the end of treatment and at follow up, respectively. Three patients dropped out of the study due to severe diarrhea.5

These studies were small in size and encouraged patients to avoid additional treatment aside from their usual anti-inflammatory and pain-relieving agents. However they were not required to disclose if other treatment was used during the study period, leaving the potential that the results could have been due to such other treatments. The second trial was uncontrolled, and the blinding was potentially compromised by the large number of gastrointestinal adverse events.

In addition to the high number of adverse events noted in antibiotic treatment groups, strong considerations should be given to the potential negative consequences of long-term antibiotic use. The long-term use of antibiotics may contribute to an increase in antibiotic resistance and place patients at a higher risk of serious secondary infections such as Clostridium difficile.


The use of antibiotics to treat low back pain has been studied only in a small number of patients who have chronic low back pain after a previous disc herniation, with bone edema classified as type 1 Modic changes. The studies that have been performed do not prove that improvement was due to antibiotics. Strong consideration has to be given to the large number of gastrointestinal adverse events seen with antibiotic treatment, and the potential that this treatment could add to the already large problems of antibiotic resistance and C. difficile infections. Therefore, the use of long-term antibiotics is not a viable option in the treatment of low back pain at this time.

Kelly M. Percival, PharmD

McKenzie C. Ferguson, PharmD, BCPS

Last updated on: October 15, 2014
First published on: March 1, 2014