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Weak immune system (immunosuppression)

Pēhanga pūnaha awhikiri

immune systemYour immune system is your body's defence against infection. It protects you from bacteria, viruses and other germs that can make you sick.

It includes your skin, lymphatic system (which is made up of your lymph glands, Peyer's patches, thymus and spleen) and white blood cells (which are made in your bone marrow).

Each part of your immune system has a different role. Some parts stop bugs entering your body. Examples of this are your skin acting as a barrier and your stomach acid killing bugs from your food. If bugs do get into your body, other parts of your immune system, such as your white blood cells act like an army to fight them.

Weak immune system

Immunosuppression and immunocompromise are the names for what happens when your immune system is weak.

People can have weak immune systems for many reasons. In the first few weeks of its life, a newborn baby has an immature immune system. Also, as a normal part of ageing your immune system gets weaker. Some conditions such as diabetes, certain cancers (lymphoma, leukaemia and myeloma) and HIV cause a weak immune system.

Sometimes, it's caused by the medicines you take, known as immunosuppressants. These are needed if you've had an organ transplant. They're also used in conditions where the body attacks its own cells (autoimmune conditions), such as rheumatoid arthritis, inflammatory bowel disease and psoriasis.

A weak immune system can also be an unwanted side effect of a medicine. For example, chemotherapy fights cancer, but it also weakens your immune system.

Risk of infection with a weak immune system

Having a weakened immune system increases your risk of infection from different kinds of bugs, such as bacteria, viruses and fungi. You are also more likely to get very unwell quickly.

If you start to feel unwell with a fever, sore throat, or cough, are passing urine more often, or have diarrhoea or vomiting, you should see a doctor as soon as possible.

Self-care with a weak immune system

You do not need to stay indoors and avoid contact with other people altogether, but you do need to avoid anyone who is unwell with a sore throat or cough, diarrhoea and vomiting, chickenpox or shingles.

You should also be very thorough in washing your hands to avoid picking up germs.

There is no special diet that you need to follow but avoid foods that are more likely to cause infection. The Ministry of Primary Industries has produced a guide to what is safe to eat and what you should avoid (link downloads a PDF).


Some vaccines are safe for you, and some aren't. The flu vaccine is safe and can help to protect you from getting the flu while your immune system is weak. But some vaccinations can make you unwell and you should discuss with your doctor if they're safe before having them. They're the live vaccines: measles, mumps and rubella, oral polio, yellow fever, BCG (for tuberculosis) and the chickenpox and shingles vaccines.

Children in your family should continue to get their usual immunisations. They will not put you at risk and it helps to protect you and your whānau (family) from infections if others get their usual immunisations.

Skin cancer risk

If you're immunosuppressed, you're more likely to get skin cancers. If you get a skin cancer, it can grow faster and is more likely to spread.

Anyone receiving an organ transplant should have a skin check by a dermatologist, then regular skin checks either by their GP or a specialist.

You can reduce your chance of developing skin cancer in the future by limiting harmful sun exposure. You can reduce the chance of skin cancer causing problems by detecting it early and having it removed before it spreads.


Whether or not your immune system will recover depends on how long you need to take the medicines that are weakening your immune system. If you're taking chemotherapy to treat a cancer, your immune system will gradually recover in the weeks after you finish chemotherapy. If you need to take an immunity-suppressing medicine for life, you'll always have to be aware of the increased risk of infection.

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Written by HealthInfo clinical advisers. Last reviewed June 2022.


See also:

Ankylosing spondylitis


Polymyalgia rheumatica

Page reference: 392691

Review key: HIIMS-392691