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Immune suppression describes a loss of immune function. It can occur for many reasons, including disease, medication, surgery, age or genetics.

We are surrounded by millions of bacteria, viruses and other germs (microbes) all the time. Some are actively helpful to us - for instance, we couldn't digest our food without 'friendly' gut bacteria. Most are harmless unless they get into our system - and it's the job of our immune system to stop that happening.

The immune system - the body's defence against disease-causing microbes (pathogens) - can be divided into:

  • Lines of first defence (our skin, saliva, the mucous membrane lining your nose, acidic stomach juices, etc).
  • Specially adapted white blood cells called lymphocytes.
  • Other types of white blood cells.
  • Your lymphatic system (a network of tubes and glands - lymph nodes or glands - which carry a fluid called lymph containing cells called lymphocytes).

See also the separate leaflet called The Immune System for more information.

Immune suppression, also known as immunosuppression or immunocompromise, means your immune system isn't working properly. This includes any or all of the defences that make up your immune system - particularly the white cells in our bloodstream, along with our spleen and lymph nodes.

When this system is suppressed, ie not working as it should, we are more vulnerable to infection.

If your immune system is suppressed, you may be more vulnerable to infection. You are more likely to need to see a doctor, more likely to need antibiotics and more likely to land up in hospital for treatment if you develop an infection, than someone who is not immunosuppressed. You can't have live vaccines if you are immunosuppressed, and you may need to take special precautions when you travel.

You are also more vulnerable to certain skin cancers if you are immunosuppressed.

The following can be causes of immunosuppression:

  • Age. Our immune systems become less effective when we become elderly.
  • Persisting (chronic) disease. Immune systems tend to become less effective as certain long-term illnesses progress. Examples include severe chronic kidney disease, chronic liver disease and diabetes mellitus.
  • Malnutrition.
  • Medicines for illness caused by the immune system attacking itself (autoimmune conditions). Examples include rheumatoid arthritis and Crohn's disease.
  • Medicines in the form of oral steroids for conditions which result in inflammation where treatment is needed to reduce inflammation.
  • Medicines taken to prevent rejection in people who have had organ or bone marrow transplants.
  • Chemotherapy or radiotherapy treatment for cancer
  • Cancers. Certain cancers can cause immune suppression, particularly those which involve the blood cells which are so crucial to our immune system. Lymphomas, leukaemias and myeloma are the cancers which may suppress the immune system.
  • Not having a spleen, due to it having been removed. Or having a spleen which does not work well. This can occur due to certain conditions such as sickle cell anaemia, thalassaemia major or lymphoma, or after radiotherapy.
  • HIV and AIDS. The human immunodeficiency virus (HIV) affects the immune system.
  • Rare genetic conditions which result in loss of immune function - for example, severe combined immunodeficiency syndrome (SCID), DiGeorge's syndrome, Wiskott-Aldrich syndrome.

Oral steroids are a common cause of immune suppression and are used in numerous conditions. They are more likely to lower your immune defences when used at high doses for long periods of time. Lower doses do not generally cause a problem. For an adult, a dose of 40 mg per day of prednisolone for more than a week may cause immune suppression, but this dose varies for other steroids and for children. See the separate leaflet called Oral Steroids for more information.

Other medicines which suppress the immune system include:

These medicines are used to treat all sorts of conditions, some of the more common ones including:

Your spleen is an important part of your immune system but sometimes it has to be removed, with an operation called a splenectomy. This may need doing if you are involved in an accident, or have an injury where your spleen is ruptured. It may need removing to stop you losing vast quantities of blood.

Sometimes it has become too large and destroys too many of your blood cells. Examples where this occurs and the spleen may need to be removed include:

See the separate leaflets called Spleen Pain and Preventing infection after Splenectomy for more information about the spleen.

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Much of the time, if you have immune suppression, you do not know you have it. However, you may be prone to getting infections more frequently. Also when you do get infections, they may be more severe and you may be more likely to develop severe complications. You may also get unusual or uncommon infections. For example, in general, healthy adults do not usually get thrush in the mouth, unless there is a good reason for it, such as using a steroid inhaler. For people with AIDS, however, thrush is common and may be very widespread or severe.

The medicines which can suppress your immune system may give you other side-effects. These vary and will be listed in the information which comes with your individual medicine.

Infections can develop and spread particularly quickly in people whose immune systems are suppressed. A sore throat, for example, is more likely to develop into a chest infection. You are more likely to get spread of any one individual infection to your whole body (sepsis), which can make you dangerously ill.

People who have immunosuppression also seem to be at higher risk of certain types of skin cancer. This includes squamous cell carcinoma (SCC), melanoma and Kaposi's sarcoma. It is not entirely known for sure why this is. It may be because the immune system helps to destroy skin cells which have been damaged by the sun. These cells, if not removed by the immune system may go on to multiply and cause cancer. It may also be that viruses (such as human papillomavirus - HPV, or herpes viruses) involved in some cancers are more likely to be present if the immune system is suppressed. Some immune-suppressing medicines may directly affect skin cells in a way which makes them more likely to develop skin cancers.

If you have immune suppression, the when-to-see-your-doctor rules change. The immune system of healthy people can fight off most minor infections within days without any medical input. That's why with most minor infections, healthy people are encouraged to take a wait-and-see approach. This means treating the symptoms and only visiting the doctor if they feel very unwell or the infection is not settling on its own.

If you have immune suppression, however, even a mild infection could become serious very quickly. So it is best to see a doctor as soon as possible rather than waiting to see how things go. Infections caught early can be treated quickly, preventing them from spreading and making you unwell. You are more likely to be given an antibiotic for a mild infection compared with someone who is not immunosuppressed, and it may well be in extreme cases that this might save your life.

So consult a doctor if you think you might have an infection, such as a sore throat, a cough, symptoms of a urine infection, food poisoning, etc.

Seek urgent medical attention if:

  • You have a high temperature (fever) over 38°C.
  • You have chills or shakes (rigors).
  • You feel generally unwell with dizziness or drowsiness or confusion.
  • You have a rash.
  • The light hurts your eyes.
  • You have fits (seizures).

If you have a child who is immunosuppressed, all the above applies. But you should also seek medical attention urgently if your child is breathing rapidly, or not eating or drinking as normal.

Also keep an eye on your skin. If you develop any scaly areas which don't clear up quickly with a good moisturising cream, or if you have a new mole or one which has changed then consult your doctor. Hopefully it won't be any kind of skin cancer, but if it is, the earlier it is treated, the better the outcome will be.

This varies with the individual medication. Some medicines require you to have regular blood tests. These monitor your blood cells (white cells, red cells and platelets), and check that numbers aren't getting too low. There may also be blood tests to check the medication isn't affecting your liver or kidney function.

For other immune-suppressing medication, you may have a regular blood test to see how well it is working. For example, if you take steroids for polymyalgia rheumatica (PMR), a blood test is done to check the levels of inflammation in your body. As these levels come down, the dose may be gradually reduced. If the blood tests show the disease is active again, you may need to increase the dose. Similar blood tests are done for monitoring of some of the medicines used to treat rheumatoid arthritis.

It may also vary over time. For example, for some medicines, such as methotrexate, you will originally need frequent blood tests every one or two weeks, whereas once you have been on them for a while, if things seem to be stable, this will drop to every three months.

Ask your GP or specialist about the monitoring requirements of your medication.

Other tests may be needed for the condition for which you are having treatment. In some cancers, for example, bone marrow biopsy might be needed to monitor what is happening. In HIV and AIDS, specific blood tests on immune function may be used to monitor what is happening.

Your specialist may also monitor you for any changes in your skin, as immune suppression can make you more susceptible to skin cancers.

Other tests and monitoring requirements will depend on the specific medication. For example, if you take oral steroids, your weight and blood pressure may be monitored, as weight gain and high blood pressure can be side-effects of this type of medication. On steroids, your bone density will also be monitored, as they can cause 'thinning' of the bones (osteoporosis), and your eyes will be monitored for cataracts.

It all depends on the cause. In some cases it can be treated, in others it is managed. For example:

  • HIV infection and AIDS are treated with specific anti-HIV medication. See the separate leaflet called HIV and AIDS.
  • Many cancers can be successfully treated, or at least their progression delayed, with chemotherapy.
  • Stem cell (or bone marrow) transplants are used in some situations. Damaged cells are replaced with normal ones. This is used in some forms of cancer, as well as some genetic immunosuppression conditions.
  • Immune suppression caused by medication should reverse if the medication is stopped. If the immune suppression is causing harm then sometimes an alternative can be used, or the dose dropped. In other cases, infection is quickly managed as and when it occurs, while the medication is continued. It depends on the condition being treated how long the medication is used for.
  • If you have had a splenectomy, the effect is lifelong, but there are ways of reducing the risk of infection (see section below).
  • In some conditions, such as genetic immune disorders, injections of antibody proteins (immunoglobulins) can be given to help the body fight infection.

Treating infections early is crucial if you are immunosuppressed. You will be given treatment for the infection. If you are unwell, or if it doesn't seem to be working, you may be admitted to hospital.

If your immune system is suppressed, the important thing is to take steps to avoid infection. This can be done in a number of ways:

  • Take general steps to avoid infection. For example, avoid eating food which puts you at risk of food poisoning. Handle raw meat safely. Use general hygiene measures to keep your home, etc, clean and germ-free.
  • Avoid close contact with people with infectious conditions where possible.
  • Ensure all routine vaccinations are up to date. (Specific recommendations are made for immunosuppressed children having their childhood vaccinations.)
  • Extra vaccinations for higher-risk people, such as an annual flu jab, and vaccination against COVID-19, pneumonia and shingles.
  • Some live vaccinations (those which contain live germs) are not given to some people who have a suppressed immune system. Always let the person vaccinating know that you take this medicine.
  • Some people who have had a splenectomy and are at particular risk of infection are advised to take a regular antibiotic, such as penicillin, on a daily basis.

Because you are at particular risk of infection, it is wise to plan very carefully for travel. Have all travel vaccinations advised for your destination. (Depending on the reason for your immune suppression, you may be advised against certain live vaccines. Be wary of travelling to countries with high risk of diseases you cannot be vaccinated against.) Avoid going to places where you wouldn't have access to good medical care if you became ill. Travel with information about your condition and medication in case you need the help of a health professional while away from your usual doctor(s). Check your travel insurance covers you if you become ill. Discuss with your doctor and consider taking some 'in-case' antibiotics and instructions for when to take them if you are at risk of specific infections. Take the usual precautions to avoid food poisoning/traveller's diarrhoea if visiting somewhere this might be a risk.

And finally, if travelling somewhere hot, use plenty of high-factor sun cream to protect your skin.

The Immune System

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Further reading and references