Top 9 Causes of Fatigue

Find out what typically causes fatigue and how your doctor figures out why you’re so tired.

Sanaz Majd, MD
4-minute read
Episode #77

56-year-old Frank came to see me in the clinic with his wife who said she had to “drag” him to my office.  Frank has been tired all the time for the past 2 months and just can’t seem get motivated enough to get out of the house.  Frank says that he just “hates the doctor’s office,” which is why he hasn’t been to one in over a decade. 

Fatigue is likely one of the top 20 complaints that I hear from my patients.  Living in today’s hectic world, we are all overworked and overstressed and this is one of the most common causes of fatigue.  Sometimes the stress can just catch up to us and cause our bodies to want to shut down and rest.  But before we blame Frank’s fatigue on stress, it’s my job to make sure it’s not anything more serious.

The History

Before I make any conclusions about Frank’s condition, I need to ask him some questions to really dissect the situation.  So I start taking what doctors call the “patient history” and I ask him about:

  1. Medications
    Some medications, like those prescribed for blood pressure, can cause fatigue as a side effect.  Frank hasn’t seen a doctor in over 10 years, let alone taken any medications.  He also denies taking any over-the-counter supplements or herbal remedies. 

  2. Alcohol/Drugs
    Excessive alcohol intake and illicit drug abuse often runs through my mind as a possible cause of fatigue, but Frank tells me he drinks one glass of red wine with dinner maybe once a week and that he’s never dabbled in any drugs.

  3. Depression
    One of the most common ways patients with depression present at the doctor’s office is with complaints of fatigue.  Often, patients are so depressed that they don’t want to go out or do the things they used to enjoy; doctors call this “anhedonia.” When I ask my patients with fatigue if they are depressed, they sometimes break down crying (this is why I always make sure to stock a box of tissues in each one of my exam rooms).  Frank tells me that although he’s had more stress at work, he’s never been happier.

  4. Excessive Caffeine
    Those who drink excessive caffeine often get a burst of energy initially, but then may crash after the effects wear off.  Frank says he drinks 1 cup of coffee in the mornings, and stays away from sodas and energy drinks.

  5. Thyroid Disease
    Hypothyroidism, where the thyroid is underactive and produces too little hormone, can slow down the metabolism and cause fatigue.  It is often hereditary, but Frank says that no one in his family suffers from this ailment.

  6. Anemia
    I always ask about heavy periods in women, and any bleeding in the stool or elsewhere in both men and women with fatigue.  This is because anemia is also on my list of possibilities anytime a patient complains of fatigue.  If our red blood cells don’t have enough iron, they can’t carry oxygen properly, causing us to feel tired.  Frank denies seeing any blood in his stools.


Please note that all content here is strictly for informational purposes only. This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider. Please always seek a licensed physician in your area regarding all health related questions and issues.

About the Author

Sanaz Majd, MD

Dr. Sanaz Majd is a board-certified Family Medicine physician who graduated from Drexel University College of Medicine in Philadelphia. Her special interests are women's health and patient education.