According to the National Institutes of Health, your body can store up to 2,000 times the amount of B12 you typically get in a day
The complex is eventually released from lysosomes and transported across the cell membrane bound to transcobalamin in the blood circulation
Hbert HL, Shepherd B, Milburn K et al (2018) Cohort profile: Genetics of Diabetes Audit and Research in Tayside Scotland (GoDARTS)
The effects of Vitamin B12, a key component, can last for several days to a week, but this can vary depending on how quickly an individuals body uses or excretes it
That means three things in practice
Seek urgent medical attention (via NHS 111 or 999 in an emergency) if you experience severe or persistent abdominal pain, persistent vomiting, signs of dehydration (such as dizziness, reduced urination, or extreme thirst), or symptoms suggestive of low blood sugar (such as shakiness, sweating, or confusion)