red urine after vitamin b12 injection B12: All You Need to Know Vitamin B12: Urine discolouration could

Research/educational use only, not medical advice

The mechanistic case is strong

Red or purple chromaturia is a side effect of hydroxocobalamin, typically resolving over several weeks.2 Additional causes of red urine include blood (e.g., traumatic catheterization, malignancy, infection), dietary ingestion (e.g., beets), and medications (e.g., rifampin, phenothiazines).3 Although benign and not warranting further evaluation by itself, hydroxocobalamin-induced discolouration of body fluids may interfere with colorimetric sensors

This makes it easier for you to get the full dose with none of it lost during digestion

Contact your GP if you experience: No improvement after 46 weeks of treatment : Whilst neurological symptoms may take longer to resolve, you should notice some improvement in energy levels or general wellbeing within this timeframe