Side effects from bypass surgery

You may have some side effects after your surgery. These will depend on the type of surgery you have had. You may not get all the side effects listed here. If you have any questions about side effects, talk to your medical team.

What's in the 'Bypass surgery' section?


You may have some pain and discomfort after surgery. You will be given painkillers to help, and the pain will get better over time.

Read more about pain after surgery.

Tiredness and fatigue

It can take some time to recover from the surgery, and you may feel tired and weak at first. It may take several weeks to be as active as you were before the operation.

Read more about tiredness and fatigue.

Feeling sick

Sometimes it can take a while for the stomach to start working again after surgery for a blocked duodenum. This is called delayed gastric emptying. It means food will take longer to pass through your stomach, which will make you feel sick. If this happens, it may take a little longer to recover. Ask your surgical team about this. You may be given medicine to help your stomach empty.

Eating after surgery

After surgery for a blocked duodenum you might need to change your eating habits. For example, you might feel full more quickly, and need to eat smaller meals more often.

Pancreatic cancer can also reduce the number of enzymes your pancreas makes. These enzymes help break down (digest) food. You may need to take pancreatic enzyme replacement therapy to deal with this and help you digest your food properly.

Your dietitian will be able to help you with your diet. If you haven’t seen a dietitian, ask to be referred to one.

Questions about side effects?

If you have any questions about side effects after bypass surgery, speak to your doctor or nurse.

You can also speak to our specialist nurses on our free Support Line.

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Updated October 2023

Review date October 2026