What is the most common cause of malaise? An in-depth look at this symptom

October 1, 2025 •

3 min read

While it can feel difficult to pinpoint, viral infections are the most frequent culprits behind the vague feeling of being unwell known as malaise. Although a simple cold can be the trigger, understanding what is the most common cause of malaise involves recognizing a broader range of potential factors, both temporary and chronic, that can lead to this universal symptom.

Quick Summary

Malaise is a general feeling of discomfort or illness most often caused by acute viral infections. However, this symptom can also indicate chronic disease, mental health issues, lifestyle imbalances, or medication side effects.

Key Points

Viral infections are the most common cause of malaise: Acute illnesses like colds, the flu, and COVID-19 frequently trigger the immune system response that causes a general feeling of being unwell.
Malaise is different from fatigue: Malaise is a feeling of sickness, while fatigue is a lack of energy, though the two often occur together.
Chronic conditions can cause malaise: Long-term issues like anemia, diabetes, heart disease, autoimmune disorders, and cancer are common underlying causes of persistent malaise.
Mental health and lifestyle play a role: Stress, anxiety, depression, poor sleep, and unhealthy diet can all contribute to feelings of malaise.
Certain medications can induce malaise: Some medications, including antihistamines and blood pressure drugs, may cause malaise as a side effect.
Seek medical help for persistent symptoms: It is important to see a doctor for malaise that lasts more than a week or is accompanied by other concerning symptoms to determine the underlying cause.

Understanding the Universal Symptom of Malaise

Malaise is a medical term describing a general feeling of discomfort, illness, or lack of well-being, often vague and hard to pinpoint. It can manifest as weakness or tiredness. While similar to fatigue, malaise is a more profound sense of being sick. The body's immune response, releasing cytokines, is thought to contribute to this feeling.

The Most Common Cause: Acute Infections

The most common cause of malaise is typically an acute infection, especially viral ones. Viral infections like the common cold, flu, COVID-19, and mononucleosis are frequent causes. Bacterial infections, such as UTIs or pneumonia, can also cause malaise.

Other Potential Causes of Malaise

Numerous other factors can cause malaise, emphasizing the need for medical evaluation if it persists. Chronic conditions like anemia, diabetes, thyroid disease, heart and lung disease, autoimmune diseases, and cancer can be sources of persistent malaise. Mental health conditions such as depression, anxiety, and chronic stress significantly impact physical well-being and can lead to malaise. Lifestyle factors like poor sleep, poor diet, and dehydration can also contribute to feeling unwell. Additionally, certain medications, including antihistamines and some psychiatric drugs, may list malaise as a side effect.

Distinguishing Malaise from Fatigue and PEM

Understanding the distinctions between malaise, fatigue, and Post-Exertional Malaise (PEM) is crucial for diagnosis and treatment. {Link: Harvard Health https://www.health.harvard.edu/staying-healthy/what-is-malaise}


Characteristic	Malaise	Fatigue	Post-Exertional Malaise (PEM)
Definition	General feeling of being unwell or sick.	Extreme tiredness or low energy.	Symptoms worsen after minimal exertion.
Primary Sensation	A sense of illness that is often hard to describe.	Exhaustion and lack of motivation.	A 'crash' or exacerbation of various symptoms.
Trigger	Infections, chronic illness, mental health, etc..	Lack of sleep, overexertion, stress, or underlying conditions.	Occurs 24-72 hours after minimal physical or mental effort.
Associated Conditions	Any health condition.	Many medical conditions, stress, poor lifestyle.	Primarily associated with ME/CFS and Long COVID.

Seeking Medical Advice for Persistent Malaise

Given the wide range of potential causes, persistent or severe malaise warrants medical attention. Consult a healthcare provider if your malaise:

Lasts over a week.
Is severe or impacts daily life.
Includes other symptoms like fever or weight loss.
Accompanies increased anxiety or depression.
Worsens with a known chronic condition.

Diagnosis and Treatment

A doctor will conduct a physical exam and review your history to diagnose the cause of malaise, potentially ordering tests like blood work or X-rays. Treatment depends on the identified root cause. This might involve rest and hydration for infections, managing a chronic condition, therapy for mental health issues, or lifestyle adjustments. For further information, resources such as Harvard Health Publishing offer valuable insights (https://www.health.harvard.edu/staying-healthy/what-is-malaise).

Conclusion: The Importance of Listening to Your Body

Malaise serves as a general indicator that something is not right. While acute viral infections are the most common cause, chronic conditions, mental health issues, and lifestyle factors can also be responsible. Due to the diverse possibilities, persistent or severe malaise should not be ignored. A proper diagnosis can help identify and address the underlying cause, contributing to overall well-being.

Frequently Asked Questions

Malaise is a general, nonspecific feeling of being unwell, discomfort, or unease in one's bodily health. It is not an illness itself but a symptom that can accompany many different health conditions.

Yes, chronic stress and mental health conditions like anxiety and depression can absolutely contribute to or cause malaise. Prolonged stress activates the body's 'fight or flight' response, which can lead to both emotional and physical exhaustion and a feeling of sickness.

No, malaise is not always serious. It is a common symptom of minor, self-limiting illnesses like the common cold. However, if malaise is severe, persistent, or accompanied by other concerning symptoms, it can indicate a more serious underlying condition.

PEM is a specific type of malaise associated with conditions like ME/CFS and Long COVID. Unlike general malaise, PEM is a worsening of symptoms that occurs after even minimal physical or mental exertion, often with a delayed onset.

You should see a doctor if your malaise lasts longer than a week, is severe, or is accompanied by other worrying symptoms such as a high fever, chest pain, or unexplained weight loss. A medical professional can help determine the underlying cause.

Yes, nutritional deficiencies can cause malaise. Not getting enough essential vitamins and minerals, such as iron or vitamin D, is a well-known cause of fatigue and a general feeling of being unwell.

A doctor will typically begin with a physical exam and a detailed review of your symptoms and medical history. They may then order specific diagnostic tests, like blood work or imaging, to help pinpoint the root cause of your malaise.