Synopsis
Refer appropriately for metabolic surgery, recognise early and late complications, and deliver lifelong procedure-specific nutritional, reproductive and medicine follow-up without losing shared-care ownership.
- NICE recommends referral for specialist bariatric assessment using BMI, significant weight-related conditions, suitability for anaesthesia and surgery, and commitment to long-term follow-up rather than automatic operation.
- Common procedures include sleeve gastrectomy, Roux-en-Y gastric bypass and adjustable gastric band; more malabsorptive operations create greater micronutrient and medicine-absorption risk.
- Surgery changes appetite biology and gastrointestinal anatomy, but it does not remove the need for dietary, psychological, reproductive and chronic-disease care.
- NICE expects structured follow-up within the bariatric service for at least two years, followed by lifelong annual nutritional surveillance in an explicit shared-care model.
- Vomiting, regurgitation and dysphagia are not normal long-term consequences; investigate stricture, band problems, marginal ulcer, obstruction or internal hernia.
- Rapid loss, poor intake, vomiting, alcohol misuse, oedema, neuropathy, ataxia or confusion creates thiamine risk; treat immediately and escalate neurologic features the same day.
- Routine supplements depend on procedure but usually include a complete multivitamin-mineral product plus iron, vitamin B12, calcium and vitamin D plans.
- Annual tests commonly include full blood count, ferritin, folate, B12, renal and liver profile, calcium, vitamin D and parathyroid hormone, with zinc, copper, selenium and fat-soluble vitamins according to procedure and symptoms.
- Avoid routine NSAIDs and review modified-release, enteric-coated and narrow-therapeutic-index medicines because altered anatomy can change ulcer risk or absorption.
- Pregnancy needs preconception bariatric and obstetric review, procedure-specific supplements and avoidance of retinol-containing vitamin A; oral contraception may be unreliable after malabsorptive surgery.
Key red flags
Intermittent or severe postprandial abdominal pain, vomiting, tachycardia or obstruction years after bypass can reflect an internal hernia; examination may be deceptively soft and CT does not always exclude it.
Poor intake or vomiting with confusion, ataxia, nystagmus, ophthalmoplegia, neuropathy, oedema or cardiac failure suggests beriberi or Wernicke encephalopathy and requires immediate treatment.
Investigation priorities
Define the procedure, revisions and expected malabsorption before interpreting symptoms.
Management branches
Severe obesity and weight-related disease persist despite appropriate non-surgical care.
- Verify current NICE BMI and comorbidity thresholds, applying lower intervention thresholds for relevant ethnic backgrounds and expedited diabetes pathways where applicable.
- Refer to a multidisciplinary service for medical, dietetic, psychological, anaesthetic and surgical assessment, including eating disorder, substance use and reproductive plans.
- Use shared decision-making to compare procedure benefits, nutritional burden, reflux or dumping risk, reversibility, local outcomes and lifelong follow-up requirements.
Key medicines
Complete bariatric multivitamin and mineral supplementTake a procedure-appropriate complete formulation every day for life, meeting BOMSS minimum thiamine, iron, zinc, copper, selenium and folate content rather than using a standard low-content retail product.Requirements differ by procedure, sex, pregnancy and laboratory results. Avoid retinol-containing vitamin A in pregnancy, prevent duplicate high doses and never assume a multivitamin replaces separate calcium, iron or B12.
Thiamine for vomiting or rapid-loss riskBOMSS primary-care guidance uses oral thiamine 200 to 300 mg daily plus vitamin B co-strong when oral intake is reliable; give immediate parenteral therapy under the emergency protocol if vomiting or neurological features impair safety.Do not wait for test results and give before glucose or carbohydrate where feasible. Neurological signs require same-day medical, neurology and bariatric review; oral absorption is unreliable during persistent vomiting.