A case of green urine due to a traditional Chinese medicine containing methylene blue.

Abnormal discolouration of the urine is always alarming to the patient and intriguing to physicians. Green colouration in urine can be of endogenous or exogenous aetiology. We present a case of green urine caused by a side effect of a traditional Chinese medicine (TCM) containing methylene blue, an uncommon occurrence. This case also highlights the importance of thorough history taking from the patient, especially diet and medications. Simple analysis in the clinical biochemistry laboratory can play a role in avoiding other expensive and unnecessary investigations.