Symptoms
Fatigue that won’t go away: causes and what to do
Is this an emergency?
This is not an emergency service. Call 911 or go to the nearest emergency room if you have:
- Chest pain or shortness of breath
- Confusion or severe dizziness
- Fainting
- Thoughts of harming yourself or suicide: call Línea PAS 1-800-981-0023, 988 or 911
- Bleeding that won’t stop, vomiting blood or black stools
Help lines
Fatigue that rest doesn’t fix has many possible causes: poor sleep, stress or depression, anemia, thyroid problems, high blood sugar, infections or medicine side effects. By video, the doctor asks about your sleep, mood and symptoms, gives you a lab order to look for the cause and helps you make a plan. If you have chest pain or shortness of breath, call 911.
Other names: Tiredness, Exhaustion, Lack of energy
Possible causes
Anemia
Tiredness or weakness from a lack of oxygen; checked with a blood count
Hypothyroidism
Fatigue with weight gain, feeling cold and dry skin
High blood sugar or diabetes
Fatigue with strong thirst and frequent urination
Low vitamin D or B12
Low B12: fatigue and tingling; low vitamin D: muscle weakness or aches; checked with blood tests
Insomnia
Sleeping too little or poorly night after night
Sleep apnea
Loud snoring, pauses or gasping in sleep, daytime sleepiness; confirmed with a sleep study
Depression or stress
Low mood, loss of interest; if you think about harming yourself, call 988
After an infection
Fatigue can linger after the flu or COVID-19
On this page(7)
What is fatigue, and when should it be checked?
MedlinePlus defines fatigue as a feeling of weariness, tiredness or lack of energy. It is not the same as sleepiness, though the two often go together. Everyone gets tired after a hard week; what is worth checking is tiredness that lasts for weeks, doesn’t improve with rest or has no clear explanation.
Get evaluated if the fatigue won’t go away and you don’t know why, especially if it comes with fever, unexplained weight loss, mood changes, strong thirst or frequent urination, or loud snoring.
How we help by video if you are always tired
You see Dr. Diana Nieves Castro, a Puerto Rico-licensed general practice physician with several years of emergency-department experience, in English or Spanish. She asks how long you have been tired, how you sleep, whether you snore, how your mood is, how you eat, whether you have heavy periods, and which medicines and supplements you take.
We evaluate, diagnose and treat. MedlinePlus lists the tests that usually help find the cause: blood tests such as a blood count, thyroid, kidney and liver tests, and a urinalysis. If needed, we give you a lab order for a lab near you and go over the results with you in a follow-up visit. If appropriate, the doctor prescribes and we send your prescription to your pharmacy. If you need a sleep study or a specialist, we refer you.
We do not prescribe stimulants or other controlled substances. MedlinePlus notes that stimulants, including caffeine, are not effective treatments for fatigue. A doctor visit costs US$79, the same price for every age. Request a visit online 24/7 — we confirm your time by email or text.
Your doctor
Dr. Diana Nieves Castro, MD
General practice physician
Several years of emergency-department experience.
Founding Executive Director of The Health Initiative.
Common causes of fatigue
The table on this page sums up the most common causes. Some clues:
- Anemia: a lack of oxygen in the body makes you feel tired or weak. See anemia.
- Low vitamins: according to MedlinePlus, a lack of vitamin B12 can cause fatigue, low energy and, over time, numbness and tingling in the hands and feet. See vitamin B12 deficiency. Low vitamin D more often causes bone pain and muscle weakness or aches.
- Underactive thyroid: fatigue with weight gain, feeling cold, dry skin or mood changes. See hypothyroidism.
- High blood sugar: fatigue with strong thirst and frequent urination. See high blood sugar.
- Poor sleep: insomnia, or sleep apnea, which causes loud snoring, pauses or gasping in sleep and daytime sleepiness.
- Stress, anxiety or depression: low mood and loss of interest also feel like tiredness.
- Infections and medicines: fatigue can linger after a cold, the flu or COVID-19, and some medicines cause it as a side effect.
Fatigue and your mood
If along with the fatigue you feel sad, hopeless or uninterested in everything, tell the doctor. If you have thoughts of harming yourself, don’t wait for an appointment: call Línea PAS at 1-800-981-0023 or 988, or 911.
What you can do at home
MedlinePlus recommends:
- Getting enough sleep each night.
- Eating a balanced diet.
- Exercising regularly.
- Finding ways to relax, such as yoga, and to manage stress.
- Avoiding alcohol and drugs.
When to go to the ER
For your safety, call 911 or go to the emergency room if fatigue comes with any of these signs. See when to go to the ER.
- Chest pain or shortness of breath
- Confusion or severe dizziness
- Fainting
- Thoughts of harming yourself or suicide
- Bleeding that won’t stop, vomiting blood or black stools
Frequently asked questions
Why am I always tired?
What tests are done for fatigue?
Can you prescribe something for more energy?
Can fatigue be depression?
About this page
Author: The Health Initiative
Medical care provided by Dr. Diana Nieves Castro, MD (PR license 24027)
Disclosure: Founding Executive Director of The Health Initiative
Published: 2026-10-02 · Updated: 2026-10-02
Sources (7)
- Fatigue (MedlinePlus, NIH) (opens in a new tab) (accessed 2026-10-02)
- Anemia (NHLBI, NIH) (opens in a new tab) (accessed 2026-10-02)
- Sleep Apnea (NHLBI, NIH) (opens in a new tab) (accessed 2026-10-02)
- Hypothyroidism (NIDDK, NIH) (opens in a new tab) (accessed 2026-10-02)
- Diabetes Symptoms (CDC) (opens in a new tab) (accessed 2026-10-02)
- Anemia due to vitamin B12 deficiency (MedlinePlus, NIH) (opens in a new tab) (accessed 2026-10-02)
- Vitamin D Test (MedlinePlus, NIH) (opens in a new tab) (accessed 2026-10-02)