A young father and his daughter are preparing lunch together.

What Causes a Weak Immune System?


Indigestion, chronic fatigue, constant infections, wounds that heal slowly… If these problems sound familiar, it is possible that your immune system isn’t functioning that well. Even though there might be several complex health reasons for your body’s defense mechanisms to function poorly, maybe you can turn things around by simply changing your habits. A lot can be achieved if you change some of your habits. Since we live in the time when our body needs the best possible protection, we need to find out the causes of weak immune system and deal with them. Are you ready to change your lifestyle for the better? Let’s go!

Why Is My Immune System Weak?

If you’re familiar with our  article Top 5 natural ways to boost your immune system,  you already know how your body deals with various outside threats. But for all those who need a recap – the immune system comprises various organs and tissues tasked with detecting and neutralising substances that can harm our body. One of its key players are white blood cells, constantly circulating through our bloodstream and looking for dangerous invaders to protect us from their harmful effects.

Normally, white are able to protect the organism without issues. However, there are certain illnesses that can affect their efficiency. Among them are chronic conditions, such as diabetes or cancer, autoimmune diseases like rheumatoid arthritis, and infectious diseases such as HIV.

While some people are already born with a weak immune system, others acquire the so-called immune deficiency due to diseases or even medication they are required to take. Among them are chemotherapy medications and corticosteroids, which are prescribed to patients with inflammations.

As we’ve already explained several times on this blog, boosting one’s immunity is a misleading concept. Causing our immune system to work in overdrive would only lead to inflammation or autoimmune disease, which means that your body would actually attack its healthy tissues. What is more, scientists agree that there is no evidence that one can actually make its immune system work better. However, it’s possible to give our natural defences the best possible support to do their best job. And just like we can give our immunity some help, we can also put some obstacles in its way.

There are several weak immune system causes, but before we tackle those, let’s take a closer look at what having low immunity even looks like …

A woman with weak immune system is sitting on a couch and holding her head. There are many used tissues next to her.

Low Immune System Signs

So, how do you even know that it’s time to take a closer look at what makes you have a weak immune system? Well, some signs are pretty obvious. Just think about a common cold. While it’s perfectly normal for healthy adults to be under the weather a few times a year, constantly catching colds is a signal that something is awry.

Besides the coughing, a runny nose and fever, people with a weak immune system also often suffer from digestion issues. They might often feel constipated or even have to deal with frequent diarrhea.

This is no coincidence as researchers will tell you that approximately 70 % of your immune system is actually located right in your gastrointestinal tract. Yes, this is the place where the good bacteria as well as microorganisms that support your immunity reside. And if their amount is low, your organism will also find it harder to protect itself from viruses, chronic inflammation or autoimmune disorders.

Slow healing wounds are the third major sign or a sluggish immune system. Don’t get us wrong, we understand that a broken heart needs time to heal, but if your skin has a hard time regenerating itself after you cut or scratch it, you might want to pay more attention to your health. Normally, your body will send nutrient-rich blood to the damaged area to help new skin grow faster, which is how your wounds normally heal. If, however, you have a low immune system, your skin won’t regenerate itself as quickly as in healthy individuals.

You should also seek for some weak immunity causes if you suffer from several infections per year (for example if you develop pneumonia more than once yearly) or if you constantly feel tired, even when getting just the right amount of sleep.

So, what can you do if you notice these signs when going about your daily business? Well, you should first determine what is causing your issues. And sometimes, weak immune system causes are plain simple and easy to get rid of.

A stressed-out, tired young man is sitting at his office computer.

Physiological Reasons for a Weak Immune System

Tell Us What You Eat …

…and we are going to tell you how well (or badly) you are treating your body’s defense mechanisms! But don’t worry! A yummy burger now and then, or a few slices of pizza won’t make your body prone to every single infection that comes your way. However, a diet full of saturated fats, sugars and salt is considered to be one of the main reasons for weak immune system.

By enjoying lots of processed foods and carbohydrates, you won’t only be impairing your immunity but also gain weight, which is further linked with lower resistance to various infections. But how does being overweight weaken your immune system? By reducing both the number and function of white blood cells in your system, preventing them from multiplying and producing antibodies needed to fight infection. Thus, gaining too much weight weakens your first line of defence against harmful substances.

On the other hand, a balanced diet including lots of fruits, vegetables and nuts is known for its ability to keep your immunity in check. What’s more – fresh fruits, delicious nuts or even vegetables present a great alternative to your usual processed snacks. Being rich in antioxidants as well as vitamins A, B, C and E, they are vital for maintaining the strength of your body’s defence system.

A peeled orange on a wooden cutting board.

And Then There Are Also Those Nasty Habits

Yes, we’ll bother you with drinking and smoking again. And we won’t stop until you quit (if you haven’t already – in this case, we salute you!).

We’ll cut you some slack this time and spare you the details on how smoking ruins your lungs, focussing instead on another important reason why it causes a weakened immune system. Tobacco smoke doesn’t only irritate your airways, it also hampers the exchange of impure and healthy air when you breathe. This makes smokers more susceptible to infections of the respiratory tract. This is especially dangerous in the autumn or winter time, when your body’s natural defences are already weakened.

Shall we proceed with excessive amounts of alcohol? Of course! Too many people still don’t know that when you’ve had too much to drink, your body’s ability to fight pathogens can be reduced. The reason lies in acetaldehyde, a major metabolite in alcohol, which is believed to impair your lungs’ natural defence against bacteria and viruses. Besides, alcohol also interferes with the process of attacking and breaking down harmful invaders. When asking yourself what makes you have a weak immune system, don’t forget to think about your drinking habits, especially in winter, a time of celebrations and festivities.

A festive toast with champagne and white and red wine – clinking of glasses.

Too Little Exercise Can Lead to Weak Immunity

Being a couch potato also belongs to weak immune system causes. By regularly including some sweating in your daily routine, you help your antibodies circulate faster, thus enabling them to catch invaders before they cause some real damage. It also releases hormones that make you happier, which prevents stress. Since this is also one of the reasons for low immunity, being active is a win-win scenario for your body.

However, if you couple a sedentary job with a relatively lazy, TV-bound lifestyle, you risk weakening your immune system. The latest research suggests that no matter your age, gender or other unhealthy habits, being inactive is a shortcut to inflammation and other chronic diseases. Do your immune system as well as your whole body a favour and try to be active at least for 30 minutes a day. Anybody should have enough time to do this!

But You Might Also Be Training too Much!

First we tell you how beneficial it is for your immunity to go out and break a sweat, then we say you might be weakening your body’s defence by training too much. Hear us out, it’s not that confusing!

What we want to stress is that if you go out and train (hard), your body also needs resting and recuperation. Doing too many strenuous training sessions with too little rest may otherwise cause the so-called overtraining syndrome, which is often the cause for a weakened immunity system.

If you feel that your natural defences are down despite not pushing yourself too hard? It might be that you spend too little time in the company of your bed. Getting enough sleep helps your body to release more cells and other antibodies that are vital for your immune system. If you don’t take care for rest and recuperation, you have higher chances of getting ill.

Elderly male cyclists are riding their bikes through a forest.

Are You Washing Hands Regularly?

Yes, we know that you’ve heard that a million times already. Please don’t get mad, we promise we’ve got something new to tell you. And yes, before you ask, we also know that not washing your hands isn’t one of many weakened immune system causes. But there is always a but!

If you don’t take care of your hand hygiene often enough, your immune system might need to work harder to protect you from outside invaders, being challenged to do this more often than it should. If you, however, take care of always having clean hands means preserving the immune function of your body until its intervention is actually really needed, for instance when the body must fight off a new virus that has virtually made the whole world stop for a moment.

Psychological Factors Affecting Your Immune System

Stress Is a Greater Issue Than You Think

Are you constantly stressed about your job? Do you worry too much about your relationship? Is someone close to you driving you crazy? These things might be the cause for your weakened immune system.

If you’re battling stress on an almost daily basis, your immune function is actually suppressed as your body cannot produce as many infection-battling white blood cells. And the story goes on! When you suffer from excessive stress, you might also put aside some other habits that help your immune system to work flawlessly. Your meals might be less healthy and you lose sleep. Watch out and relax before it’s too late.

Think about meditation, take short walks or treat yourself with your favourite meal. We know that stress is unavoidable and that there is no switch to simply get rid of it. However, if you notice that your health is the victim of constant worrying, you should try to relax and protect your body from further damage.

An elderly woman is meditating on a sofa in her home.

Emotional Trauma Also Weakens Your Immunity

Recent studies show that a tragic event can have a very similar effect on your immunity as too much stress. Some studies suggest that a sudden break up or even death of a loved person can weaken your organism’s immune response, thus increasing the risk of more frequent or even more severe viral infections like flu.

Just like in the case of stress, bereavement is linked to increased cortisol production. This hormone actually prevents our immune system from responding too quickly, for example when we are in a fight-or-flight situation. However, if high cortisol levels stick around for longer, this can start affecting your immunity.

Everybody Needs a Friend Sometimes!

Do you spend most of your free time alone and aren’t too happy about it? Chances are that you are already paying the price of loneliness … with poor health. Experts warn that anxiety that is related to living a pretty much solitary life leads to more stress, which naturally leads to a weakened immune system. On the other hand, even a short hug can have an incredibly positive effect on your emotional wellbeing and thus on your susceptibility to illnesses.

A warm hug between friends.

Are you always serious? Cheer up a bit!

How often do you laugh? Can you take a joke? Do you get excited about future events?All these things can have an immensely positive impact on your stress hormone levels and thus also on your immune system.

Don’t believe us that taking life too seriously can actually have an effect on your immunity? Well, let us tell you that laughing, joking and having fun in general will give the white blood cells a proper boost. Scientists say that even anticipating something funny or exciting can reduce your stress levels and thus help you avoid a weakened immune system.

Frequently Asked Questions

1. Which habits have a negative impact on our immune system?

Bad diet rich in saturated fats, sugar, and salt, smoking and drinking alcohol, too much or not enough physical exercise, bad hygiene (especially not washing your hands well), stress and lack of having fun and relaxation have a negative impact on our immune system.

2. How do we know that our immune system is weakened?

If we are getting tired and sick more often (coughing, runny nose, high temperature,…), we suffer from indigestion or our wounds are taking a long time to heal, there is a big chance that our immune system is not working properly.

3. What are the causes of a weakened immune system?

Unhealthy lifestyle, stress and emotional trauma make our immune system work less effectively, but they are more rarely connected to the diseases that impede our immune function (autoimmune diseases, such as rheumatoid arthritis, lupus, diabetes, psoriasis…).

4. Does physical exercise affect the immune system?

Regular physical activity accelerates the circulation of antibodies that recognize and eliminate harmful substances in the body because physical exercise also releases the happy hormone and, at the same time, reduces stress. Therefore, it undoubtedly helps in our body’s immune defense. However, be careful: if you overdo it with physical exercise, you can weaken your immune system. Always give your body enough time to recover after more strenuous sport activities.

5. Can Donat help in strengthening the immune system?

Donat natural mineral water does not have a direct effect on the body’s immune resistance. However, it has been clinically proven that regular consummation of Donat accelerates digestion and thereby takes care of the health of our gut. Since 80 % of immune cells are in the digestive tract, healthy intestines are also of key importance for the immune system, so drinking Donat is undoubtedly useful as a support of our immune system.

Would you like to help your digestion and immune system?

Choose chapter:

How to Effectively Manage Stress through Nutrition for a Healthy Digestive System