Linezolid-induced tooth discoloration in a 10-year-old child undergoing treatment for rifampicin-resistant pulmonary tuberculosis

Dear Editor, Linezolid can have rare side effect of tooth discoloration especially in children due to microbiome shifts and chromogenic bacterial overgrowth, that can recur despite professional dental cleaning. We report a case of 10-year-old boy with rifampicin-resistant pulmonary tuberculosis who developed reversible yellow-brown anterior tooth discolouration after starting a linezolid-based all oral longer regimen. A 10-year-old male child, weighing 24 kg presented with a confirmed diagnosis of rifampicin-resistant pulmonary tuberculosis, established through the Xpert MTB/RIF® assay. The patient was promptly initiated on an all-oral longer treatment regimen which consisted of oral tablets of linezolid at a dose of 300 mg/day, moxifloxacin at 400 mg/day, clofazimine at 50 mg/day, cycloserine at 250 mg/day, and pyrazinamide at 750 mg/day. Approximately after one month of treatment, the patient’s parent observed a gradual onset of yellow-brown discolouration affecting the upper and lower anterior teeth [Figure 1]. This change was progressive and noticeable, prompting parent’s concern. To evaluate this issue, a dental consultation was done. There was no history of any accompanying tooth pain or any functional impairment. Importantly, there was no prior history suggestive of contributing factors such as inadequate dental hygiene practices, concurrent iron supplementation or any regular consumption of beverages like tea, coffee or coloured sodas that could lead to extrinsic tooth discoloration. The examination revealed that the discolouration was extrinsic in nature, without any structural involvement of the enamel.Figure 1: Brownish discoloration of anterior teeth following one month therapy with linezolidIn an effort to manage the discolouration, the patient underwent a professional dental cleaning procedure. This intervention successfully removed the yellow-brown stains initially restoring the teeth to their normal appearance [Figure 2]. However, the discolouration re-emerged within just 20 days following the cleaning, suggesting an ongoing causative factor linked to the patient’s ongoing treatment. Given the temporal association, where the staining first appeared shortly after the initiation of the antitubercular regimen and recurred despite cleaning, linezolid was identified as the probable culprit. Linezolid has been documented in medical literature to cause reversible extrinsic tooth discoloration in both paediatric and adult patients, often attributed to changes in oral microbial flora that promote chromogenic bacteria.Figure 2: Teeth after dental cleaning procedureDespite this side effect, linezolid was continued in the regimen due to its essential contribution to the treatment of rifampicin-resistant tuberculosis. Future management could involve more frequent professional cleanings or exploring adjunctive oral hygiene measures to minimise the impact, while ensuring the overall success of the anti-tuberculosis treatment. Linezolid is a cornerstone drug in WHO-recommended MDR/RR-TB regimens, including BPaLM/BPaL-based combinations, due to its potent bactericidal activity. While safety monitoring usually emphasises myelosuppression, neuropathy, and lactic acidosis, cosmetic effects such as extrinsic tooth discoloration are increasingly reported in children.[1-5] Paediatric cases typically show yellow-brown anterior staining, occasionally with black hairy tongue, arising within weeks of therapy which resolve with cleaning or after drug cessation. In our case, temporal association, recurrence despite professional cleaning, and exclusion of alternatives support linezolid as the main cause. Pathogenesis likely involves deposition on salivary pellicle, altered surface affinity, or microbiome shifts leading to chromogenic plaque.[3,5] Children may be more vulnerable due to enamel maturation and microbiome dynamics, though effects remain superficial and reversible. Management should emphasise counselling, oral hygiene, dietary precautions, and professional cleaning, alongside continued monitoring for hematologic, neurologic, and metabolic toxicities. Early recognition of this rare side effect supports adherence to drug thus preserving regimen efficacy.[2,4,5] Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the parent(s)/legal guardian(s) of the patient have given their consent for the patient’s images and other clinical information to be reported in the journal. The parents/guardians understand that the patient’s name and initials will not be published and that due efforts will be made to conceal the patient’s identity; however, anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.