Tube feeding through a vein (parenteral nutrition)

Parenteral nutrition (PN) means giving nutrients and fluid into the bloodstream through a tube.

About parenteral nutrition (PN)

Parenteral nutrition (PN) means having nutrients and fluid directly into the bloodstream. It is a type of tube feeding for nutritional support.

PN is usually used for people who cannot take nutrients in through their digestive system. For example this may be because:

  • they had surgery on the small bowel
  • there is a blockage in the bowel (bowel obstruction)
  • it is difficult to insert the tubes used for enteral nutrition (EN). This can happen after some types of surgery to the head and neck or surgery to the stomach.

PN is sometimes called TPN, which means total parenteral nutrition. But it is not always possible to provide total nutrition through the bloodstream. So it is more commonly called PN.

How PN is given

PN is usually given through a thin tube which is inserted into a large vein in your neck or chest. The tube is called a central line. Sometimes you have it through a thin tube in your arm that goes up into a vein in your chest. This is called a PICC line (peripherally inserted central catheter).

Parenteral nutrition

Sometimes, a vein in the arm is used, but this is less common. This is like having an ordinary drip. It may be used if you only need feeding for a short time, usually less than 10 days. It is also only possible if the amount of fluid you can have is not restricted. This is because PN needs to be more diluted if an arm vein is used. The doctors will decide the best type of feeding for you.

PN is usually started slowly. Your feed will be reduced over a few days when you no longer need it.

Benefits of PN

PN can give you nutrition even when the digestive tract is not working. It can allow the digestive tract to rest so that it can heal – for example, after surgery to the stomach or surgery to the bowel.

You may also have PN if you have severe vomiting, diarrhoea or a sore mouth, and cannot have enteral nutrition (EN) tube feeding.

Possible problems with PN

It is possible for an infection to develop either inside the line or around the exit site. You should tell your doctor if:

  • the exit site becomes red or swollen
  • you notice fluid coming from the exit site
  • you develop a high temperature (fever) or feel unwell.

You may be given antibiotics. If the infection is serious, the tube may have to be removed.

It is possible for a blood clot (thrombosis) to form in your vein at the tip of the central line. If this happens, the tube may have to be removed. You may be given anti-clotting medicines to stop this from happening. The medicines are usually added to the feed.

You will have regular blood tests while having PN. This is to check that your levels of sugar, minerals and other substances are normal. PN can sometimes change your blood sugar levels. You may need insulin to control your blood sugar levels if they are too high. Your feed will be specially prepared for you each day according to your blood sugar levels and nutritional needs.

About our information

  • References

    Below is a sample of the sources used in our nutritional support information. If you would like more information about the sources we use, please contact us at

    Arends J, Baracos V, Bertz H, et al. ESPEN expert group recommendations for action against cancer-related malnutrition. Clinical Nutrition, 2017; 36, 5, 1187-1196. Available from (accessed Jan 2020).

    Bischoff SC, Austin P, Boeykens K, et al. ESPEN guideline on home enteral nutrition. Clinical Nutrition, 2020; 39, 1, 5-22. Available from (accessed Jan 2020).

    National Institute for Health and Care Excellence (NICE). Nutrition support in adults. Quality standard [QS24]. Published: 30 November 2012. Available from (accessed February 2020).

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 August 2020
Next review: 01 August 2023

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

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