Bariatric Surgery Side Effects

Bariatric surgery is a procedure performed on obese individuals in order to help them achieve rapid weight loss. The risks associated with bariatric surgery fall into two main categories: those related to restricted food intake and rapid weight loss and those associated with the surgical procedure itself.

Accordingly, side effects can be categorized as:

  • Immediate post-operative complications
    • Infection of the wound and of the operative site  (affects around 1 in 20 patients)
    • Internal bleeding (occurs in around 1 in 100 patients)
    • Development of blood clots (occurs in around 1 in 100 patients). Clots may develop in leg veins (deep vein thrombosis) or travel up to the lungs causing a pulmonary embolism, which can be life threatening.
  • Death

The immediate complications of bariatric surgery can result in a patient’s death. Pulmonary embolism, severe bleeding, major infection, stroke, or heart attack are all conditions that put the patient’s life at serious risk. The estimated risk of death after gastric band insertion is around 1 in 200 and after gastric bypass surgery, the risk is around 1 in 100.

Factors that raise the risk of dying due to post-operative complications include age, male gender, high blood pressure, increased risk for pulmonary embolism and a body mass index of 50 or above. Risks for pulmonary embolism include a history of pulmonary hypertension, deep vein thrombosis, and blood clots.

Development of gallstones

Gall bladder stones are a common outcome of bariatric surgery, with stones developing in around 1 in 12 individuals. Gallstones are aggregates of chemicals and cholesterol that eventually clog up the gall bladder. The stones may be symptomless or may cause intense pain in the abdomen as well as nausea, vomiting and jaundice.

Stoma blockage

Stoma blockage is a common complication of gastric bypass surgery that occurs when the opening (stoma) that connects the stomach pouch to the small intestine becomes blocked by a piece of food, resulting in persistent vomiting. The condition occurs in around one-fifth of patients and is treated by directing a small flexible tube called an endoscope into the stoma where a balloon attached to the endoscope is inflated to remove the obstruction. To avoid stoma blockage, food must always be taken in small bites and chewed thoroughly.

Excess skin

Rapid weight loss among obese individuals results in skin becoming excessively loose and folded. Folds of skin are most typically acquired around the breasts, back, abdomen, limbs, and hips and are normally most apparent 12 to 18 months after surgery. The folds can be unsightly and may harbour moisture leading to infections and rashes. These excess skin flaps can be removed and the skin tightened using cosmetic surgery.

Effects on mental health

Rapid weight loss may have a detrimental effect on mental health, with many patients suffering from depression and anxiety after surgery. Patients may also develop relationship problems with their partner. Additionally, social occasions orientated around meals may make the patient feel isolated and anxious due to their much reduced appetite and restricted diet.

Slippage of the gastric band

Gastric band slippage is a problem that affects around 1 in 50 patients who have had an adjustable band fitted. The band slips out of position and the stomach pouch becomes bigger than it should be, resulting in nausea, vomiting and heartburn. Further surgery is then required to repair the slippage.

Intolerance to foods

Food intolerance occurs in around 1 in 35 patients who have had bariatric surgery and may develop years after the procedure. Foods such as red meat may bring on heartburn, nausea and vomiting.



Further Reading

Last Updated: Feb 26, 2019

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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