Symptoms and Causes of a Weak Immune System

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Discover what are the tell-tale signs that your immunity might not be working as well as it used to and find out the possible causes behind low immunity

Unwell womanOur immune system is the shield that keeps us protected from harmful viruses and bacteria. When our defences are up and everything in our body works as it should, germs can do us little harm. But if there is a chink in the immunity armour, we can end up getting sick constantly. The COVID-19 pandemic has reminded us that a weak immune system can leave us completely unprotected when facing a virus.

So, how can you tell when you’ve got low immunity and what are the causes of a weak immune system? Getting to know how immunity works will help you make informed decisions to boost your chances of keeping bacteria and viruses at bay.

What are the symptoms of a weak immune system?

Unfortunately, there is no warning light that goes off to let us know when we’re dealing with low immunity. Many of the signs of a weak immune system are subtle and can be confused for something else. But there are a few tell-tale signs that should prompt you to have a conversation with your GP about boosting your immunity.

Frequent infections

If you find yourself on a course of antibiotic multiple times a year, your body might be sending you a red flag about your immunity. Frequent infections indicate that there is an imbalance in your immune system and it should be further investigated. So, if you’re constantly nursing ear infections, skin infections, long episodes of sinusitis or any other type of infection, it could be time to give your immunity a boost.

Getting colds

Woman with coldA weak immune system can sometimes manifest through frequent colds as well. If you feel like you’ve just bounced back from your cold and you’re already getting the sense that another one is coming your way, this could be a symptom of a weak immune system. Low immunity means your body isn’t able to fight off germs and that’s exactly what might be happening if you’ve got a constant case of the sniffles.

Feeling tired

Our bodies’ supply of energy is limited and if they have to constantly fight intruders such as bacteria or viruses due to low immunity, there isn’t much fuel left for many other things. This is why if you’re feeling drained and weak, a compromised immune system might be the culprit. However, there are many other possible reasons for getting exhausted quickly: poor sleep and vitamin deficiencies are some of the most common ones.

Digestive problems

Our digestive system and our immune system depend on each other to keep us healthy and thriving. The microorganisms that live in our gut protect us from harmful bacteria. But if the balance is off and our immune system is not properly supported by the good bacteria in our digestive system, symptoms such as diarrhoea and constipation are not far behind.

Skin rashes

Skin is the largest organ of the body, so it’s natural to look there as well for signs of a weak immune system. Look out for skin irritation, allergic reactions or skin conditions such as psoriasis, as these could mean that your immunity is struggling to keep up.

What causes a weak immune system?

Low immunity can be either inherited or acquired later in life. Here are some of the most common causes for low immunity.

Genetic factors

The immune system can be compromised via issues in the genetic code passed down from parents to children. This means that there can be a genetic aspect to the reason why your immunity is low and there is nothing that can be done to prevent it. But eating well, practicing good hygiene and keeping stress levels down can go a long way in preventing infections.

Lifestyle choices

Woman with headacheA diet lacking essential nutrients, smoking or drinking too much alcohol can lead to low immunity as well. Not sleeping enough can also weaken your defences, so making sure that you keep good, healthy habits in your life can benefit your immune system tremendously.


Chemotherapy medication and corticosteroids are designed to inhibit the white blood cells and thus might also lead to low immunity. Talk to your doctor if you think there is a possibility that the treatment you are on might affect your ability to fight off infections.


Our immune system relies on a good supply of white blood cells to do its job properly. Unfortunately, as we age, it is possible that the organs producing them might stop doing so in the numbers required for a strong immune response.


Many health conditions can also weaken our immunity. These include HIV and certain types of cancer. Even fighting off the flu can leave our immune system temporarily weakened.

If you’re worried about your immune system not working as it should, you can always talk to your GP. Simple solutions such as aiming for a balanced diet and plenty of sleep may help offer your immunity a much-needed boost. Any nutrient deficiencies should be resolved either through changes in diet or by considering vitamin supplements. If you want to find out more about ways to increase your immunity, check out our step-by-step guide. And don’t forget to add these immunity-boosting foods to your diet as well.



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