7 signs of a weak immune system and what you can do about it

  • PUBLISHED November 02, 2023
  • AUTHOR Donna

Key takeaways

  • Your body might give you clues that the immune system is not working properly.
  • If you’re more likely to succumb to illness, have digestive problems or if it takes longer for skin wounds to heal, you may have a weaker immunity.
  • There are a number of dietary and lifestyle changes you can make to strengthen the abilities of your body to better fight infections.

7 signs of a weak immune system and what you can do about it

The immune system protects your body from infections and diseases. But sometimes it doesn’t work the way it should. Certain signs may point to a weaker immune system and it’s important not to ignore them. This way, you can take the necessary steps to bring your protective powers back in gear.

Digestive problems

Your gut plays a major role in regulating the immune balance – almost 70 percent of your immune system is home in your digestive tract. 1 Healthy microbes that reside there help prevent inflammatory processes, but if their numbers are not maintained, “bad” bacteria quickly multiply and start damaging the gut lining. This may cause gas, diarrhea or constipation.

Frequent colds

Most of us will go through a couple of colds each year. But if you’re constantly battling a runny nose and other symptoms (which also take longer than normal ten days to overcome), it could mean that your immune system can’t keep up with the constant demand to produce white blood cells which fight cold-producing viruses.

Wounds that take longer to heal

Immune cells are essential for wound healing and skin repair. If your body’s defenses are sluggish and weak, your skin can’t regenerate effectively. Instead, your wounds linger and take longer than normal to heal. 2

Frequent infections

Another tell-tale sign of a weak immune system is frequent illnesses. Warning signs of a frail immune system include more than four ear infections in a year or developing pneumonia at least twice. Frequent infections mean that your body cannot fight off the bad bacteria that cause infections. 3

You feel tired all the time

Sometimes you can get all the sleep needed but you still feel drained. If you suffer from exhaustion and persistent tiredness, it might be a consequence of a compromised immune system. 4

Cold hands

A peculiar symptom, but the cold hands phenomenon, also known as Raynaud’s disorder, can imply lupus, which is an auto-immune disease where the immune system attacks healthy tissue. 5 Raynaud’s phenomenon is characterized by a temporary constriction of blood vessels and typically affects fingers and hands. 6

Hair loss

The immune system can also (mistakenly) attack your hair follicles, causing your hair to shed. The condition is called alopecia areata and it can affect all parts of your body, not just the scalp. The good news is that the hair follicles usually survive the attack and that your hair can regrow. 7

What makes your immunity weaker

Old age

As we age, our immune system starts dwindling, especially quickly after we hit sixty. 8 This is due to cell changes that lead to a slower response of the immune system, increasing the risk of getting sick. 9 Aging also renders flu and other vaccines less efficient 10 while giving rise to micronutrient deficiencies, which may worsen already declining immune functions. 11

Lack of sleep

When you sleep, your body releases cytokines. These are small protein cells that are essential in managing your immune and blood cells. When you have inflammation in your body, the number of cytokines will increase, giving your immunity a signal to activate itself. 12 Lack of (quality) sleep, on the other hand, may decrease the production of cytokines and, in turn, increase the risk of contracting an infection. The same process can also make your recovery from illness last longer. 13 As a rule of thumb, you should get seven or eight hours of deep sleep per night, while children will need a few hours more.


When we experience stress, we release hormones, most notably cortisol, which prepare our body for a fight-or-flight response. 14 Normal amounts of cortisol are also important because they help fight inflammation 15 but nothing in excess is ever healthy. Indeed, constant stress reduces the activity of pathogen-fighting white blood cells which are needed to combat infection. 16 , 17 Unmanaged stress can also influence sleep, mood and appetite – all important elements of the immune system.

Low vitamin D

Vitamin D is known to boost white blood cell production and help strengthen your defenses against diseases. The micronutrient also decreases inflammation, which again supports your immune response. Clinical trials showed that supplementation with vitamin D may help prevent or treat the common cold and the flu. 18 , 19 , 20

Not eating well

What you eat influences your immune system. 21 Eating lots of saturated fats, ultra-processed foods, sugar and salt is likely to impair the body’s defenses by making T cells – a type of white blood cells – slower to react. 22 Junk food also promotes inflammation and can increase the risk of chronic diseases. In addition, it can skew the balance of bacteria in the digestive tract, leading to a weakened gut wall and increasing the risk for chronic inflammation.


Unhealthy diet often leads to obesity, another consideration that can hamper immune functions and increase the risk of bacterial and viral infections. 23 Obesity is also associated with low-grade chronic inflammation, while obese patients who are hospitalized are more likely to develop secondary infections and complications. 24

Smoking and alcohol

Here is a no-brainer: heavy drinking decreases the production of infection-fighting white cells which increases the risks of infection. In fact, research shows that drinking five to six drinks in one go can suppress the immune system for up to 24 hours. 25 Over time, drinking can lead to longer-term problems, more intense illnesses and symptoms lasting longer.

Similarly, cigarette smoke compromises the balance of the immune system and increases the risk for several immune and autoimmune disorders 26 , 27 – this is when the immune system mistakenly attacks the body’s healthy cells and tissues.

Certain medication

Medications that are used in cancer chemotherapy to prevent organ transplant rejection can be immunosuppressive 28 , meaning they (intentionally) weaken the immune system. The same is true for corticosteroids used for allergies or asthma while frequent use of antibiotics has been shown to damage microbiome diversity in the gut, which can directly impair immune response. 29

What can you do to boost your immunity

Make sure you maintain a healthy and balanced diet. There’s a long list of foods that are known to fortify your body’s protective functions. To name a few: fruits and veggies, fiber-rich foods, prebiotics such as garlic, onions, and leek that feed microorganisms, or probiotics (kefir or yogurt) which help digest food. 30 , 31

You also need enough protein, healthy fats like omega-3 and an alphabet of vitamins – A, B, C, D, E and K. In addition, iron, calcium and zinc are essential for an up-and-running immune system.

Consider supplements. For various reasons, you can’t necessarily receive all the micronutrients from food alone. In our dedicated article, you can learn more about the vitamin and mineral supplements that can be in fact useful.

Get enough sleep. As we’ve learned, a good night’s rest will give your body a chance to unleash the protective cytokines.

Stress management. To prevent stress from wreaking havoc on your immune system, keep it in check with relaxation. Some people like to meditate, do yoga or go for a massage. Find what works for you.

Practice personal hygiene. Start at the source and stop an infection before it begins. Wash your hands regularly with mild soap and cover your mouth when you cough.

Exercise regularly. Research shows that physical activity has the potential to flush bacteria out of the lungs and airways, reducing your chances of getting a cold or the flu. 32

Primary immune deficiency: when weak immunity is genetic

Some people are born with a weak immune system or one that doesn’t work as it should. This is called primary immune deficiency. There are hundreds of disorders that can weaken the immune system, giving a free pass to germs and viruses. 33 , 34

⁠Infections in people with primary immune deficiency are also more likely to last longer than in most people because they’re harder to treat. The most common are ear infections, pneumonia, bronchitis, skin infections and digestive problems. Primary immune disorders are caused by genetic changes and in most cases, there’s no cure, you can only treat the symptoms. 35


  1. https://connect.uclahealth.org/2021/03/19/want-to-boost-immunity-look-to-the-gut/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5471802/
  3. https://www.aaaai.org/Tools-for-the-Public/Conditions-Library/Immuno-Deficiency/recurrent-infections-immunodeficiencies
  4. https://www.theguardian.com/society/2018/dec/17/chronic-fatigue-syndrome-could-be-triggered-by-overactive-immune-system
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4689071/
  6. https://my.clevelandclinic.org/health/symptoms/17861-cold-hands
  7. https://www.aad.org/public/diseases/hair-loss/types/alopecia/causes
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291468/
  9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3582124/
  10. https://academic.oup.com/jid/article/198/5/632/865026?login=false
  11. https://www.hsph.harvard.edu/nutritionsource/nutrition-and-immunity/
  12. https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/cytokines.html
  13. https://www.mayoclinic.org/diseases-conditions/insomnia/expert-answers/lack-of-sleep/faq-20057757
  14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3079864/
  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4263906/
  16. https://health.umms.org/2020/11/10/stress-immune-system/
  17. https://health.clevelandclinic.org/what-happens-when-your-immune-system-gets-stressed-out/
  18. https://pubmed.ncbi.nlm.nih.gov/30675873/
  19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164750/
  20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949172/
  21. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7146186/
  22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6340979/
  23. https://www.nature.com/articles/s41366-021-01035-6
  24. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817078/
  25. https://adf.org.au/insights/alcohol-immune-system/
  26. https://www.cdc.gov/tobacco/sgr/50th-anniversary/pdfs/fs_smoking_overall_health_508.pdf
  27. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5352117/
  28. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/immunosuppressive-therapy
  29. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4709861/
  30. https://www.hsph.harvard.edu/nutritionsource/nutrition-and-immunity/
  31. https://my.clevelandclinic.org/health/articles/14598-probiotics
  32. https://medlineplus.gov/ency/article/007165.htm
  33. https://primaryimmune.org/about-primary-immunodeficiencies
  34. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930833/
  35. https://www.cdc.gov/genomics/disease/primary_immunodeficiency.htm
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