Skip to main content

Complications of weight loss surgery

Possible complications of weight loss surgery

Weight loss surgery is a common and safe procedure. However, as with any operation there are risks. Your doctor will explain these to you.

Blood clots 

Blood clots are possible after weight loss surgery because of how the blood flows and clots after surgery. Blood clots often start in the lower leg (deep vein thrombosis) or may sometimes dislodge and travel to the lungs (pulmonary embolism).

If you have a blood clot that causes pain or swelling, your doctor can give you anticoagulant medicines to help.

Stomach leak

In the days or weeks after a gastric bypass or sleeve gastrectomy, there's a small chance that food could leak out of your tummy (abdomen).

This can cause a serious infection inside your tummy that will need antibiotic treatment.

Gastric band slipping out of place

If you have gastric band surgery, there's a small risk that the band could move out of position.

This can cause:

  • heartburn
  • nausea (feeling sick)
  • vomiting (being sick)

See a GP if you have these symptoms and they do not go away. If your band has moved, you'll need further surgery to put it back in place or remove it.

Wound infection

Wounds can become infected after surgery. Keeping a wound clean will reduce the risk of infection and encourage the healing process.

Blocked gut

The stomach or small intestine sometimes becomes narrower or blocked after weight loss surgery and food can get stuck.

This can be caused by scarring and reduced blood flow to the area.

Reduce the risk of a blockage by:

  • cutting food into small chunks
  • chewing thoroughly
  • not drinking during meals


Gallstones are small stones, usually made of cholesterol, that form in the gallbladder. They can form if you lose weight quickly.

Excess skin

As you lose weight after surgery, you may be left with excess folds and rolls of skin, particularly around your breasts, tummy, hips and limbs.

Surgery, such as a tummy tuck, can be used to remove the excess skin. But it's usually considered cosmetic surgery so it's not always available on the NHS.

Ask a GP if surgery to remove excess skin after weight loss surgery is provided on the NHS where you live.

Immediate action required: Call 999 or go to A&E if:

  • you have difficulty breathing and pain and swelling in your leg
  • you have chest pains and pain and swelling in your leg
  • you have severe tummy pain
  • you're bleeding non-stop from your bottom
  • there's a lot of blood, for example, the toilet water turns red or you see large blood clots
  • you're vomiting blood or poo, or your sick looks like coffee grounds or soil

Urgent advice: Ask for an urgent GP appointment or get help from NHS 111 if:

You've had weight loss surgery and you have:

  • redness, tenderness, swelling or pain in your leg that is not getting better or gets worse
  • a high temperature or you're feeling hot and shivery
  • a fast heartbeat
  • tummy pain
  • fast breathing
  • difficulty swallowing
  • regular vomiting (being sick)

These symptoms could be a sign of a blood clot or a problem with your stomach.

You can call 111 or get help from 111 online.

Non-urgent advice: See a GP if:

  • you have pain in or around a wound
  • you have red, hot and swollen skin
  • pus is coming from a wound

Page last reviewed: 5 February 2024
Next review due: 5 February 2027