Why Do I Keep Getting Sick?

You’re not ending up in hospital. You’re not critically unwell. But every few weeks, there seems to be another sore throat, cough, streaming nose, headache or crushing wave of fatigue.

It is enough to cost you another day of work, another day of school, another cancelled dinner or another week away from exercise.

And eventually, you begin to wonder:

Why do I get sick so often? Is there something wrong with my immune system?

Frequently, the answer is not one serious immune disorder. More often, it is an accumulation of repeated exposure, inadequate recovery, poor sleep, prolonged stress, nutritional gaps or another condition that feels remarkably like a recurring infection.

Frequent illness doesn’t always mean a “weak” immune system

A person working in an open-plan office, commuting on crowded transport or living with children attending childcare or school may simply encounter a large number of respiratory viruses.

Young children in childcare can experience multiple respiratory infections each year, particularly when they first enter group care. Adults living or working closely with them then experience their own seemingly endless procession of colds.

Sometimes, what feels like repeated infection is not infection at all. Allergic rhinitis, asthma, chronic sinus inflammation or reflux can produce recurring congestion, coughing, throat irritation and fatigue. That is one reason it helps to examine the pattern, rather than just treating each episode in isolation.

Stress is physical and emotional

A difficult week won’t automatically “switch off” your immune system. But prolonged psychological stress can alter the way immune and inflammatory responses are regulated and has been associated with greater susceptibility to upper respiratory infections.

This doesn’t mean that illness is “all in your head”. It means that a nervous system kept continually on high alert has fewer opportunities for restoration and recovery. 

Stress also tends to travel with other immune disruptors: shorter sleep, less exercise, irregular meals, more alcohol and less time outdoors.

Sleep may be one of the most important immune foundations

Sleep isn’t lost time. It’s active biological repair.

Experimental studies have found that shorter sleep duration and poorer sleep efficiency are associated with a greater likelihood of developing a cold after viral exposure.

For adults, protecting a consistent sleep window, reducing late-night work and allowing genuine recovery after illness may be more valuable than adding another supplement to the bathroom cupboard.

Vitamin D: particularly relevant at the end of winter

Vitamin D has important roles throughout the body, including in normal immune function. In Australia, levels tend to be highest after summer and lowest toward the end of winter.

People at greater risk of deficiency include those who spend most of their time indoors, cover most of their skin, have darker skin, avoid sunlight completely, have certain malabsorption conditions or are older and housebound.

Sunlight is our principal source, but this is not an invitation to accumulate sun damage. Sensible incidental outdoor exposure should always be balanced with current sun-protection advice.

Vitamin D supplements are not a magic bullet. But it is a sensible approach to identify and correct deficiency where it is likely or documented and to proactively supplement through the winter if your job is indoors and you are not being exposed to sunlight on large surface areas of skin. 

Vitamin C: freshness and preparation matter

Vitamin C supports normal immune function and is found in foods such as:

• capsicum
• kiwifruit
• citrus fruit
• berries and blackcurrants
• broccoli, cabbage and Asian greens
• tomatoes and cauliflower.

Vitamin C is relatively fragile. Time in storage, cutting, heat and prolonged cooking in water can reduce the amount that eventually reaches your plate. Including a mixture of fresh produce, frozen vegetables and lightly cooked vegetables can help preserve it.

People who are eating well, don’t necessarily need a supplement. Australia’s “five vegetables and two fruit” principle is an excellent foundation.

Regular vitamin C supplementation can modestly shorten the duration and reduce the severity of coughs, colds and flu like illnesses for some people. 

Where do we get zinc?

Zinc is essential for normal immune function, tissue repair and many cellular processes.

Good dietary sources include:

• oysters, shellfish and fish
• red meat and poultry
• eggs and dairy products
• legumes such as chickpeas, lentils and beans
• nuts and seeds
• wholegrain breads and cereals.

Zinc from plant foods is not always absorbed as efficiently as zinc from animal foods, so people following a fully plant-based diet might need thoughtful dietary planning. 

Zinc supplements taken early in an illness can shorten symptoms.

What about B vitamins and protein?

Your immune system is built from actual raw materials. Adequate protein, energy and micronutrients matter.

Meat, fish, eggs, dairy products, legumes, tofu, nuts, seeds, wholegrains and leafy vegetables collectively provide protein, iron, zinc and several B-group vitamins. Vitamin B12 deserves particular attention in people eating no animal products and in those with conditions or medications that affect absorption.

Again, the objective is not to “supercharge” immunity. It’s to ensure your body is not trying to defend and repair itself while under-fuelled.

Could it be iron deficiency?

Iron deficiency doesn’t necessarily cause every recurrent cold, but it can leave a person feeling perpetually exhausted and make each illness much harder to recover from.

Possible clues include:

• persistent fatigue or reduced exercise tolerance
• breathlessness
• palpitations or a rapid heartbeat
• restless legs
• headaches or dizziness
• pale skin
• unusual cravings, particularly for ice
• heavy menstrual bleeding or another source of blood loss.

Iron deficiency can occur before overt anaemia develops. A full blood count and ferritin may be appropriate when the symptoms and clinical history suggest it. Iron supplements should not be taken without knowing whether iron deficiency is actually present and why.

Reduce the number of viruses reaching you

Nutrition is only one part of prevention. Reducing exposure remains enormously practical.

Respiratory viruses spread more readily in crowded, poorly ventilated indoor environments. Useful precautions include:

• opening windows and doors where practical
• using effective mechanical ventilation or HEPA filtration
• keeping recommended vaccinations current
• staying home when acutely unwell
• washing or sanitising hands appropriately
• carrying a well-fitting P2 or N95 mask for crowded indoor settings, public transport or occasions when someone nearby is coughing.

You don’t have to wear a mask everywhere to benefit from having one available when the situation calls for it. 

When should recurrent illness be investigated?

Please arrange a medical review when infections:

• are unusually severe, prolonged or difficult to clear
• repeatedly affect the chest, sinuses, ears or another single site
• require frequent courses of antibiotics
• involve unusual organisms or repeated thrush
• are accompanied by weight loss, persistent fever or night sweats
• occur alongside ongoing breathlessness, palpitations or profound fatigue
• continue to take you away from work, school or normal life.

A thoughtful review may include your illness timeline, exposure patterns, sleep, stress, nutrition, medications, allergies, asthma and relevant examination findings. Blood tests should then be targeted to the clinical picture rather than ordering every available vitamin level. In selected circumstances, further immune testing may be appropriate.

The bottom line

There is no single capsule that creates an invincible immune system.

What genuinely helps is less glamorous but far more useful: adequate sleep, enough nourishing food, corrected deficiencies, time outdoors, good indoor airflow, current vaccinations, sensible mask use and a GP prepared to look carefully at the complete pattern.

Your immune system may not be broken. But if illness repeatedly steals days from your life, you deserve more than being told, “It’s probably just another virus.”

At Walker Street Doctors, we can help investigate what may be contributing and build a practical plan to help you stay well more often.