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Guide to weak immune systems

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A weak immune system can lead to constant colds, fatigue and infections. Explore the signs of poor immunity, and how you can support your immune system.
Your immune system protects you from illness and infection. It is a complex network of cells and organs – including your skin and white blood cells – which work together as a first and second line of defence.

Unfortunately, sometimes our immune systems don’t work as well as expected, which can make you more susceptible to viruses and infections.

In this article, we are going to look at what it means to have poor immunity, the signs of a weak immune system and how you can help to support your immunity through simple diet and lifestyle choices.

What is poor immunity?

Poor immunity is when your immune system is under pressure and not performing the way it should. If you have poor immunity, you may feel fatigued, under the weather, and experience tummy troubles more frequently.

What can cause poor immunity?

You could be born with an inefficient immune system, or it could be weakened over time. As you age, your immune system can become less effective. There are several other lifestyle factors that can also lead to a weakened immune system, including: 1 
  • Not sleeping well 
  • Smoking
  • Drinking alcohol
  • Pushing your body too hard
  • Stress
  • Poor nutrition
There are also a number of medical aspects that can negatively impact your immune system including: 1
  • Immunodeficiency disorders (primary immunodeficiency or secondary immunodeficiency disorder) 
  • Radiation & cancer therapies 
  • Exposure to harmful chemicals 
  • Conditions such as: multiple sclerosis, cancer, Crohn’s disease, or Chronic Fatigue Syndrome 
  • Certain medications

What is immunodeficiency?

Immunodeficiency disorders are a group of disorders where most or all your immune system stops working properly. If you are constantly battling illness and infections, this may be a sign you have a weak immune system and you should check with your doctor.

There are two main types of immunodeficiency: primary and secondary.2

Primary immunodeficiency (PID) is usually genetic and present from birth. There are more than 300 known types of PID that can range from mild to severe and can result in recurrent infections, poor growth, and other health problems.3 In certain instances, individuals with a mild form may remain unaware of their PID until adulthood.4

If the immune system becomes damaged or weakened later in life, it is referred to as secondary immunodeficiency disorder (SID).5 SIDs, sometimes referred to as acquired immunodeficiency disorders, are more common than PIDs and are caused by a primary illness like HIV or external factors such as malnutrition or certain drug regimens.6

Are immunocompromised and immunodeficient the same thing?

Yes and no. Immunodeficiency is just one type of immunocompromisation.7

Immunocompromisation is a more general term that refers to any condition or situation that weakens the immune system, while immunodeficiency refers specifically to a weakened immune system due to certain genetic or acquired defects.

People who have immunodeficiency or autoimmune disease are considered immunocompromised, but there are other things that can also make someone immunocompromised, like cancer, cancer treatments, metabolic disorders, or just getting older.

Symptoms of a weak immune system

There are certain tell-tale signs that can indicate if you have a weak immune system. We’ve listed five of them below: 
  1. You’ve constantly got a cold
    Having the old cold every now and then is normal, but if you’ve permanently got one, then your body could be telling you that your immune system’s really suffering. Permanent colds are an indicator that your body isn’t equipped to fight off germs. Catching two to three colds during the winter, that linger for more than 7-10 days at a time, is a sign your immune system isn’t quite right.
  2. You develop regular ear infections
    If you are prone to contracting ear infections frequently (more than four infections a year), it could possibly point towards weak immunity. As with colds, if you’re constantly getting ear infections, then your body’s immune system isn’t quite firing on all cylinders.9
  3. You’re always tired
    Most people feel tired as a result of the busy, always-switched-on lives we now all lead, but if you’re feeling permanently drained, then your immune system may not be operating properly.10 This means you can get worn out quicker because your body’s having to work so hard to fit off germs, infections and bacteria.10

    Handpicked content: How to fight fatigue
  4. You’re feeling really stressed
    According to research, long-term stress is capable of weakening the immune system due to the fact it reduces our lymphocytes, the white blood cells that fight off infection.11 The lower your white blood cell levels, the more likely you are to catch a cold or other form of infection.10,11

    Handpicked contentHow to tackle stress
  5. You’ve got digestive issues
    If you experience diarrhoea for two to four weeks, then your immune system may not be functioning properly and may actually be harming the lining of your small intestine or digestive tract.

    Constipation can also be a red flag too. If your bowel movements are hard to pass or look like small pellets, your immune system may be forcing your intestine to slow down.

    This may also be being caused by bacteria, viruses and other health conditions too.12

Are you at risk of a weakened immune system?

We should all keep a close eye on our immune system health and support it by living a healthy and active lifestyle.

Some people might be at greater risk of a damaged immune system. If you have a family history of primary immunodeficiency disorders, for example, then your risk of having a primary disorder (or passing one on to your children) is higher.5

Anything that threatens your immune system could potentially lead to secondary immunodeficiency disorder.

How can you help your immune system?

You may be able to support your immune system better by making a few small changes. Simple immune-supporting lifestyle tips: 
  • Reduce stress: Stress can impair the activity of immune cells, such as natural killer cells and lymphocytes, which play a crucial role in fighting off infections. Chronic stress can also lead to elevated levels of cortisol, a hormone that suppresses the immune system.12 
  • Get a good night’s sleep: Sleep plays a crucial role in regulating the immune system.13 During sleep, the body produces and releases cytokines, which are proteins that help regulate immune responses. These cytokines are essential for fighting off infections.14 
  • Avoid drinking too much alcohol: Excessive alcohol consumption can weaken the immune system and make it less effective in fighting off infections.15 It can impair the function of immune cells, such as white blood cells, which are crucial for defending the body against pathogens.16 
  • Do not smoke: Smoking can suppress the production of antibodies and impair the activity of immune cells, such as natural killer cells and T cells, which play a crucial role in defending against infections.17 
  • Exercise regularly: Exercise is known to reduce stress levels by releasing endorphins, which are natural mood-boosting chemicals. A recent study also suggests that regular exercise could enhance the immune response against various microbial antigens.18 
  • Maintain a healthy weight: Not only is maintaining a healthy weight important for better overall health, there is evidence to suggest that obesity is associated with an impaired immune response.19,20 
  • Eat a balanced diet: Ideally, you want to be getting your ‘five a day’, as recommended by the NHS – or your 30 plant points each week. Ensure your diet incorporates some, or all, of the vitamin and minerals, that are primarily associated with good immune system health (Vitamin A, Vitamin C, Zinc, Selenium and Vitamin D).
Explore more ways that you can support your immune system here.

The final say…

  • Poor immunity occurs when the immune system is not functioning properly, leading to increased susceptibility to illness and infection. 
  • Factors that can cause a weak immune system include genetics, aging, poor sleep, smoking, alcohol consumption, stress, and poor nutrition. 
  • Immunodeficiency is a medical condition characterised by a weak immune system, which can be either primary (genetic) or secondary (acquired). 
  • Immunocompromised individuals have a weakened immune system, which can be caused by immunodeficiency, autoimmune diseases, cancer, cancer treatments, metabolic disorders, or aging. 
  • Symptoms of a weak immune system include frequent colds, regular ear infections, chronic fatigue, high stress levels, and digestive issues. 
  • People with a family history of primary immunodeficiency disorders or those who have factors that threaten their immune system are at a higher risk of weakened immunity. 
  • Supporting the immune system can be done through reducing stress, getting enough sleep, avoiding excessive alcohol consumption, and smoking, exercising regularly, maintaining a healthy weight, and eating a balanced diet rich in immune-boosting nutrients.


1.      https://ncbi.nlm.nih.gov/pmc/articles/PMC7711810/

2.      [HP1] https://www.uhb.nhs.uk/services/immunology/immunodeficiency.htm

3.     https://www.cdc.gov/genomics/disease/primary_immunodeficiency.htm

4.     http://www.immunodeficiencyuk.org/whatarepids/basics [HP2] 

5.     https://pubmed.ncbi.nlm.nih.gov/20042227/[HP3] 

6.     http://www.immunodeficiencyuk.org/static/media/up/secondaryimmunodeficiency.pdf[HP4] 

7.     https://primaryimmune.org/news/breaking-down-common-terms-immune-deficiency-space[HP5] 

8.    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173442/pdf/main.pdf

9.     https://www.nhs.uk/conditions/ear-infections/

10.  https://academic.oup.com/sleep/article/38/9/1353/2417971[HP6] 

11.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2475648/

12.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3337124/

13.  https://www.nature.com/articles/nri1369

14.  https://www.sleepfoundation.org/physical-health/how-sleep-affects-immunity [HP7] 

15.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4590612

16.  https://clinmedjournals.org/articles/iasar/international-archives-of-substance-abuse-and-rehabilitation-iasar-2-006.php

17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7985448/[HP8] 

18.  https://karger.com/cpb/article/37/2/735/73020/Regular-Exercise-Enhances-the-Immune-Response

19.  https://www.obesityaction.org/resources/obesity-and-the-immune-system/ [HP9] 

20.  https://pubmed.ncbi.nlm.nih.gov/27088328/



The advice in this article is for information only and should not replace medical care. Please check with your GP or healthcare professional before trying any supplements, treatments or remedies. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Before taking any supplements or minerals, it’s best to make sure you’re getting all the nutrients through your diet first.

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