INTRODUCTION: Intravesical instillations of BCG are recommended for the treatment of high-risk non-muscle-invasive bladder cancer. However, their prolonged use remains limited by the associated potentially serious adverse effects or complications. The purpose of this article was to provide updated recommendations for the diagnosis and management of adverse events (AEs) or complications of intravesical BCG instillations. MATERIALS AND METHODS: Review of the literature in Medline (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using the following MeSH keywords or a combination of these keywords: `bladder,` `BCG,` `complication,` `toxicity,` `adverse events,` `prevention,` and `treatment`. RESULTS: AEs or complications of BCG included genitourinary and systemic symptoms. The most common complications (cystitis, moderate fever) should be treated symptomatically and may require adjustment to allow patients to have the most complete BCG treatment possible. Serious complications are rare but must be identified promptly because of the life-threatening nature of the disease. Their management is based on the combination of anti-tuberculosis treatments, anti-inflammatory drugs and the definitive discontinuation of BCG. CONCLUSION: The management of BCG AEs requires early identification, rational and effective treatment if necessary, and discussion of the continuation of treatment for each situation.