Lethargy can refer to feelings of fatigue as well as a lack of mental or physical motivation. It can be a sign of a health condition.
Lethargy causes you to feel sleepy or fatigued and sluggish. This sluggishness may be physical or mental. People with these symptoms are described as lethargic.
Lethargy can be related to an underlying physical or mental condition.
Lethargy can cause some or all of the following symptoms:
- changes in mood
- decreased alertness or decreased ability to think
- low energy
People with lethargy may act as if they’re in a daze. They may move more slowly than usual.
Many kinds of acute illnesses can make you feel lethargic. This includes the flu or a stomach virus. Other physical or medical conditions can also cause lethargy, such as:
- carbon monoxide poisoning
- hydrocephalus or brain swelling
- kidney failure
- Lyme disease
- pituitary diseases, such as pituitary cancer
- nutrition deficiencies
- sleep apnea
- traumatic brain injury
Lethargy can also be the result of mental health conditions. These include:
Lethargy can also be a side effect of taking certain medications, such as narcotics.
Symptoms of lethargy may require emergency medical attention, especially if they come on suddenly. Seek emergency medical attention if you experience lethargy along with the following symptoms:
- chest pain
- unresponsiveness or minimal responsiveness
- inability to move your limbs on one side of your body
- disorientation, such as not knowing your name, the date, or your location
- fast heart rate
- paralysis on one or both sides of your face
- loss of consciousness
- rectal bleeding
- severe headache
- shortness of breath
- vomiting blood
Any noticeable, marked changes in behavior accompanied by lethargy are often cause for concern. Seek immediate medical attention if you experience thoughts of harming yourself along with lethargy. The Healthline FindCare tool can provide options in your area if you don’t already have a doctor.
You may also want to make an appointment at your doctor’s office if you experience any of these symptoms alongside lethargy:
- aches and pains that don’t go away with treatment
- difficulty sleeping
- difficulty tolerating hot or cold temperatures
- eye irritation
- fatigue that lasts longer than two weeks
- feelings of sadness or irritability
- swollen neck glands
- unexplained weight gain or loss
Lethargy in babies or young children
Babies or young children can also experience lethargy. Symptoms in babies that may need immediate medical attention include:
- difficult to rouse
- fever greater than 102°F (38.9°C)
- dehydration symptoms, such as crying without tears, dry mouth, or few wet diapers
- sudden rash
- vomiting forcefully, especially for more than 12 hours
Your doctor will usually take a full medical history to discuss any of your previous medical conditions.
They may also perform a physical exam that can include:
- listening to your heart and lungs
- checking for bowel sounds and pain
- evaluating your mental awareness
Diagnostic testing typically depends on what your doctor suspects may be an underlying cause. For example, if your doctor thinks you may have a thyroid disorder, they may order blood tests to determine if your thyroid hormones are high or low.
Your doctor may order imaging studies, such as a CT or MRI scan, if they suspect the cause is brain-related, such as a head injury, stroke, or meningitis.
Treatment for lethargy depends upon its underlying cause.
For example, they may prescribe antidepressants if your lethargy is caused by depression or another mental health disorder.
You can practice healthy habits at home to reduce the fatigue related to lethargy. Examples include:
Make an appointment with your healthcare provider if these healthy habits don’t help your symptoms.