woman with symptoms of a weak immune system

5 symptoms of a weak immune system

We all have an immune system; it forms an integral part of how the human body functions.

You may not have thought too much about it because it’s something you can’t see. But it’s responsible for a lot and is constantly working away within our bodies to protect us from getting ill.

What is the immune system?

Our immune system isn’t just one thing, e.g. one organ or a muscle within our bodies. It represents a collective group of organs, cells and chemicals that are responsible for enabling us to fight off germs, infection and disease.

These organs, cells and chemicals are our white blood cells, antibodies, the complement system (which is made up of proteins), lymphatic system, spleen, thymus and bone marrow.

And as if the immune system wasn’t enough to protect us against nasty microbes, we also have our skin, lungs, digestive tract and bodily fluids, such as our saliva and tears, all working away to defend us too.1 While the vast majority of us are born with an immune system, it is possible for babies to be born without one, making them extremely vulnerable to infection. This rare disease is estimated to occur in over 1 in 100,000 births. In families where parents are genetically related, this rate can increase to 1 in 5,000 births.2

What causes a weak immune system?

Immune deficiency diseases can lead to our immune systems not working properly. You can be born with them (primary immunodeficiency disease) or you have secondary immunodeficiency disorders. People with a family history of primary immunodeficiency disorders are at higher risk of developing them.

Essentially, anything that weakens the immune system can lead to a secondary immunodeficiency disorder.3 Other examples include:
  • Ageing – as fewer white blood cells are produced
  • Protein deficiencies
  • Lack of sleep – our body produces proteins while we sleep

Weak immune system symptoms

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 a while, is a sure sign your immune system isn’t quite right.5

2. You develop regular ear infections

By this, we mean more than four infections a year. As with colds, if you’re constantly getting ear infections, then your body’s immune system isn’t quite firing on all cylinders. It could possibly mean you have an underlying health condition.6

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. This means you can get worn out quicker because your body’s having to work so hard to fit off germs, infections and bacteria.7

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. The lower your white blood cell levels, the more likely you are to catch a cold or other form of infection.8

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 is also an alarm bell 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.9

How to look after your immune system

If you look after your immune system, then hopefully it’ll be better able to look after you. Here are some ways you can look out for it:

Overall wellbeing

Stress has been linked to causing immune system disruption, so where possible, try to reduce your stress levels.

You can do this by:10
  • Getting a good night’s sleep
  • Not drinking too much alcohol or caffeine
  • Chatting through your worries with people you trust or writing them down
  • Relaxing by using mindfulness, meditation or breathing exercises
  • Doing more of what you love/enjoy doing most


Ideally, you want to be getting your ‘five a day’, as recommended by the NHS. You may also want to go one step further by making sure your diet incorporates some, or all, of the vitamin and minerals, that are associated with good immune system health.

They include:11
  • Vitamin A – is found in liver, milk and cheese and dark green leafy vegetables and orange fruit
  • Vitamin C – is present in fruit and vegetables, including peppers, kiwis, oranges, tomatoes, blackcurrants and broccoli
  • Zinc – eat meat, poultry, eggs, cheese, as well as root veg, nuts and seeds, and wholegrain cereals and breads.
  • Selenium - is found in nuts and seeds, grains, vegetables, eggs, poultry, fish and shellfish
  • Vitamin D - mostly comes from sunshine, but is also found in oily fish, eggs, fortified breakfast cereals, spreads and dairy products

Other measures to support your immunity

Other measures include: not smoking, exercising regularly to get more of those ‘feel good’ endorphins pumping around your body, maintaining a healthy weight and trying to avoid infection by washing your hands regularly and cooking meat thoroughly.12

Hopefully, your body will show/tell you if your immune system isn’t as strong as it should be by demonstrating symptoms like those listed above.

It’s also possible to take a blood test to determine if your body has the correct level of infection-fighting proteins (immunoglobulin) in your blood. The test can also measure blood cell and immune system cell levels. Abnormal numbers of certain cells can indicate an immune system defect. For more advice on this, speak to a medical professional.

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Last updated: 8 September 2020