13 Symptoms That Point to a Weak Immune System

(Last Updated On: September 5, 2018)

We all know someone who radiates good health. They jump out of bed in the morning and whizz through their day without an ounce of fatigue. They have great skin, healthy hair, and they’re never ill. They probably aren’t just lucky; the chances are they have a robust immune system which keeps them free from illness and full of energy. If you find that you come down with every bug that goes around and you feel under the weather most of the time, your immune system probably needs a little help.

The Role of the Immune System

The Role of the Immune System

So, what is our immune system exactly, and what does it do? The immune system is made up of a lot of different cells which protect the body from parasites, bacteria, viruses, and the growth of tumors.

What makes up the immune system?

The Bone Marrow

The cells of the immune system form in the bone marrow. The bone marrow produces cells called B cells, which produce antibodies to fight infection, killer cells, which can kill tumor and viral infected cells, granulocytes, which break down bacteria in the body, and red blood cells.

The Thymus

The function of the thymus is to produce T cells. T cells are responsible for the body’s immune response when a foreign body or toxin enters the bloodstream. Their cells can also kill viruses and bacteria. The cells can be found in the liver, lungs, blood, and intestines.

The Spleen

The spleen filters the blood. It is made up of B cells, T cells, killer cells, red blood cells and cells called macrophages. Macrophages are like scavengers, they pick up and ingest foreign bodies in the blood, whether it be a virus, parasite, or bacteria. Macrophages carry foreign bodies to the spleen to be destroyed and to initiate an immune response in the body.

The Lymph Nodes

Lymph nodes are found throughout the body and are a kind of filter for the immune system. The lymph nodes drain fluid from our body’s tissues, foreign bodies are filtered out and the lymph is returned to the bloodstream.

Signs of a Strong Immune System

You rarely catch a cold, or any other illness for that matter

The most visible sign of having a good immune system is that you will hardly ever catch colds or infections. If you do get sick, the symptoms tend to be milder, and the illness doesn’t tend to last as long.

You don’t tire easily

If your immune system is healthy, you will have plenty of energy and won’t suffer from fatigue too often.

A healthy immune system can fight off infection or viruses, though this does not mean that you will never require medical intervention for an illness. Medicine is often needed to reduce inflammation, which is the cause of most of the unpleasant symptoms that you get when you’re ill. However, the fact that the inflammation occurred in the first place is because your immune system at work!

What can compromise the immune system?

What can compromise the immune system

A weakened immune system can’t protect the body from illness. Your immune system might be weak if you have cancer, heart disease, blood disorders or HIV. If you have one of these conditions, it is possible that your immune system can become overwhelmed and you can die from a simple infection that a healthy immune system could fight off. If you don’t suffer from one of these illnesses, you could still be weakening your immune system in the following ways:

Binge Drinking

Alcohol can destroy antibodies necessary for fighting disease. It can cause dehydration and nutritional deficiency which harms immunity. A study in a biomedical journal found that even a single incidence of binge drinking can weaken the immune system for up to a few days.

Smoking and exposure to smoke     

Smoking causes inflammation in the body, and the chemicals can weaken immune defenses. It is well known that people, especially children, who are exposed to secondhand smoke suffer from more respiratory infections.

Not getting enough sunlight     

Exposure to the sun makes our bodies produce vitamin D which makes our disease-fighting T cells function at their best. Vitamin D deficiency is linked with an increased risk of infection. Try to get at least 10-15 minutes of sun exposure per day, without sunscreen.


Stress and worry affect your immune system. Stress increases the production of a hormone called cortisol which can affect the immune response, the digestive system, and the reproductive system.

Lack of personal hygiene      

Poor hygiene exposes you to more germs and potentially harmful bacteria which cause illness. However, studies have shown that the lack of exposure to germs in childhood can increase the risk of disease as there is no chance to build up immunity. Washing your hands regularly, showering daily and keeping your teeth clean can all reduce the risk of getting infections.

Not getting enough sleep    

A lack of sleep is associated with a weak immune function. The body repairs and restores itself during sleep, and prepares its defenses. Without sleep, this doesn’t happen, leaving you more prone to infections and other chronic illnesses.

Being sedentary      

Regular moderate exercise strengthens the immune system, though don’t push yourself too hard. A study in the Journal of Applied Physiology found that strenuous exercise depletes the immune system for up to 24 hours.


Drinking plenty of water helps flush toxins out of the body and gives the immune system a helping hand. Dehydration can affect your energy levels and even your sleep quality, both of which can impact upon immunity.

Overusing antibiotics     

The misuse of antibiotics can lead to you becoming resistant to their effect so they might not work as well as they should. You will end up needing stronger treatment which will increase the chance of unwanted side effects. Remember, antibiotics are for bacterial infections, not viruses.

Signs That Your Immune System is Weak


If you always feel exhausted, and you get tired quickly, it could be a sign that your immune function isn’t too high. Of course, fatigue can have a lot of causes so see your doctor if the tiredness persists.

Frequent Infections

If you often pick up respiratory or urinary infections, it means that your immune system is overwhelmed and can’t fight invading viruses and bacteria as it should.

You Always Catch a Cold or Have a Sore Throat    

If you pick up every bug going, your immune system might not be working well. See your doctor to discuss possible reasons why you might be more prone to illness, and if there’s anything underlying going on.


Some people are allergic to dust and pollen, but they respond more than most and become quite ill. This is a sign of an overwhelmed immune system which needs a little help.

Injuries That Are Slow to Heal

Our skin is the first line of defense against invading viruses and bacteria. If the immune system is low, the skin can become infected, invaded by bacteria, and you will notice that wounds will be slow to heal.

Weight Loss or Weight Gain

If the immune system is impaired, the body will not be able to protect itself, so it musters all its available energy to fight infection, which can result in weight loss. The immune system also works in the digestive system to prevent the growth of bacteria and parasites. If the immune system is weak, parasites and bacteria can flourish and reduce the amount of nutrients absorbed from food. This can also lead to weight loss. Weight gain is also associated with low immunity. If fat cells are stored rather than broken down for energy, the liver has to work overtime to help break fats down, rather than being able to fulfill its primary role of getting rid of toxins from the system.

Digestive Problems

If you suffer from digestive issues like diarrhea, stomach infections, and nausea, it’s a sign that your immune system might be weakened. Bacteria and cells live in your gut that are an essential part of your immune system, so if all is not well, it’s likely that your immunity is not that great either.


If the immune system is compromised, sometimes it can mistake healthy red blood cells for invaders. The immune system attacks and destroys the red blood cells, which can lead to anemia.

Hair Loss

If the immune system is in overdrive, it can attack other cells in the body. If the immune system attacks the hair follicles, it can cause hair loss. A severe form of this is alopecia, which can cause loss of eyelashes and eyebrows too.

Joint Pain

When the immune system is impaired, it can start to attack healthy tissue and cause damage to it, so if you are regularly suffering from joint pain, your immune system might be a little off-kilter.

Mouth Ulcers

Mouth ulcers often appear when we are run down or stressed, or in other words, when the immune system is compromised.


Cancer cells can sometimes hide from the immune system so they can’t be identified, so they are quite clever. The cancer cells can prevent the immune system from responding effectively. A healthy immune system can generally recognize invading cells and destroy them. A weak immune system is more easily defeated by stronger, more organized cancer cells.

What can you do to improve immunity?

There’s no magic pill to improve immunity, you have to adopt some healthy habits to keep your system functioning as it should.


Not getting enough exercise can make you sluggish and it can affect your immune system. Exercise is excellent for general immunity, and you don’t need to be an Olympic athlete, even walking has been shown to benefit your immune system. Research shows that people who exercise regularly have more efficient white cells which fight infection. And as we know, exercise is known to release endorphins into the bloodstream; the body’s happy hormone, which reduces stress and promotes sound sleep. These are essential for good immunity.

Eat a Healthy Diet

Proper nutrition is essential for the proper functioning of your immune system. A diet high in sugar and alcohol can feed infections so you might want to avoid these if your immune system is low. Ensure that your diet contains plenty of vitamins, minerals, and antioxidants, so include plenty of colorful fruits and vegetables. Other immune boosting foods include garlic and mushrooms, both of which have antiviral and antibiotic properties.

Get Enough Sleep

Apart from making you chronically fatigued, lack of sleep can make you prone to illness and infection. If sleep deprivation is chronic, it can lead to diabetes and heart disease.  When you sleep, the body heals itself. If you don’t sleep, your body does not get the chance to repair and restore, and your immune function is impaired. Research has shown that 7 hours of sleep per night is associated with an optimal immune function.

Learn to Manage Stress

When your body is under constant stress, you’re more prone to illness and infection. Stress hormones such as cortisol and adrenaline are released into the bloodstream when we are under stress, and these weaken the immune system.

Find out what works for you regarding managing stress, whether it’s meditation, yoga or listening to music.

Don’t Abuse Alcohol or Drugs

Drinking too much alcohol can reduce the ability of the body’s white cells to fight infection. A moderate amount of alcohol, such as red wine can have some health benefits due to the antioxidants. Recreational drugs also affect the white blood cells and inhibit their disease-fighting function.

Nurture Your Relationships

People with healthy personal relationships and good support networks tend to be healthier and have better immune systems. A healthy sex life can even improve immunity. A study of students found that those who had intercourse regularly had higher levels of an immune system protein called immunoglobulin. Sex can reduce stress and promote better sleep too.

Final Thoughts

If you are always tired, come down with every bug going, and just feel like you’re dragging your feet all the time, that chances are that your immune system isn’t functioning as well as it could. The immune system is a fantastic thing. If you think about the numbers of potential germs and bacteria that are just waiting to invade our systems at any given time, it makes you realize how hard our cells work to combat the nasties.

If you have a chronic illness, or if you are receiving cancer treatment, for example, the immune system is likely to be low, and you must be extra careful not to pick up any infections as they could potentially be much more severe for you than they would be for a person with a healthy immune system.

immune banner - 13 Symptoms That Point to a Weak Immune System

But if your immune system is not compromised, factors in your lifestyle could be to blame for poor immunity. Drinking too much alcohol and smoking can inhibit immune function, as can lack of sleep, lack of exercise and a poor diet. Our immune system is very powerful, but it can only do so much, and it needs a little help from time to time. When it becomes overwhelmed, we become unable to fight infection, we might have skin trouble and digestive problems. It’s our body’s way of telling us that something is not right and that we have to make changes.

Stress has a significant effect on immunity. Who doesn’t get stressed these days? A little bit of stress is stimulating, but too much stress can impair our immune function. The fast pace of modern life is too much at times, so we need to be aware that work hard, play hard is not always going to be an option. Sometimes we have to listen when our body is telling us to slow down and look after ourselves better. We need to remember to keep life simple, to nurture our relationships and friendships, which will ultimately make us healthier, happier, and more fulfilled.

Our immune system works tirelessly to protect us, and we don’t give it a second thought until something goes wrong. Until we experience a sore throat, the inflammation, the stomach problems, which is our immune system fighting desperately hard to tackle any invading bugs.

We get one body, and we need to look after it. Our bodies are complicated pieces of machinery which have been protecting us from disease, adapting to changing surroundings and lifestyles and helping us to survive since the beginning of time. Our bodies are not cut out for modern life; for processed diets and sedentary lifestyles, yet they still survive. Take a moment to think about what an amazing thing that is. Think about what we put our bodies through every day, yet they do (mostly) what we ask of them. Be kind to your body. Nourish it with healthy food, condition it with exercise and balance it with healthy products, after all, it has to last you a lifetime.




Updated: September 05, 2018 by Dr. Kimberly Langdon M.D. All medical facts and points stated on this page are correct as of this date. Please be aware that new content and additional references were added in this last update. All the content and media has been uploaded by Lily Greene our webmaster, who is also in charge of page design. 

Written by Irina Radosevic MD
Irina graduated from the University of Belgrade, School of Medicine as a Doctor of Medicine (MD) and spent over 3 years working in the Clinical Hospital Center Zvezdara, in the Department of Emergency Medicine. She also undertook a postgraduate in Cardiology from the same University and had previously worked for over a year as a Physician and Nutritionist Dietitian for the Fitness club Green Zone. She eventually left her chaotic but fulfilling job in the ER to pursue her passion of writing, travelling and mountain climbing which has included writing a first aid course for the alpine club of Belgrade. Irina currently works as a VA for PintMedia focusing on medical and travel writing. Feel free to connect with Irina on LinkedIn and FaceBook. Her CV can be seen here.