You should contact your GP or NHS 111 if you experience: Persistent diarrhoea lasting more than 7 days in otherwise healthy adults Blood or mucus in stools , which may indicate inflammatory bowel disease or infection Severe abdominal pain or cramping that is worsening or different from previous digestive symptoms Unexplained weight loss alongside bowel changes Signs of allergic reaction , including rash, itching, swelling, or difficulty breathing (call 999 or go to A&E for severe reactions) Neurological symptoms such as numbness, tingling, balance problems, or memory difficulties, which may indicate B12 deficiency is not being adequately treated Seek help sooner if you have red flag symptoms, are pregnant, immunosuppressed, elderly, or have significant underlying health conditions
Frequently Asked Questions Are vitamin B12 injections more effective than oral supplements
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Do not extend the 28-day window to compensate, and do not leave it out again
9 PMCSubcutaneous drug injection review: pharmacologic considerations
Snchez-Villegas A, Doreste J, Schlatter J, Pla J, Bes-Rastrollo M, Martnez-Gonzlez MA
