What Is Lethargy—And How Do You Treat It?

Lethargy is a term for when someone is feeling drowsy and experiencing an unusual lack of energy and alertness. You may have also heard lethargy referred to as fatigue. 

There are times when lethargy is normal, like if you’ve just engaged in physical activity or haven’t gotten enough sleep. But lethargy can also be a sign of something more serious and should be brought to a healthcare provider’s attention. 

What Are the Symptoms of Lethargy?

Lethargy is a state of exhaustion, beyond a normal feeling of tiredness. If you are lethargic, you are exhausted during or after usual activities. Or you might not even have enough energy to start those usual activities.

There are several common symptoms that are associated with lethargy:

• Lack of energy
• No motivation
• Drowsiness
• Apathy (lack of interest or enthusiasm)

Feeling lethargic can negatively affect your reaction times, attention, concentration, short-term memory, and judgment.

Depending on what that underlying cause is, you may have other symptoms that accompany your lethargy and that are specific to the underlying cause.

What Causes Lethargy?

Lethargy has a wide range of causes. It can be a normal response to physical activity, emotional stress, boredom, or lack of sleep. Less often, lethargy can be a symptom of a serious underlying health condition.

Lethargy may be a symptom of almost any medical condition, including:

• Depression or grief
• Iron deficiency
• Insomnia, obstructive sleep apnea, and other sleep disorders
• An underactive or overactive thyroid gland
• Autoimmune diseases
• Cancer
• Diabetes
• Heart failure
• Traumatic brain injury

Certain medicines may also cause lethargy. These include:

• Sedatives
• Antidepressants
• Antihistamines
• Blood pressure medicines
• Sleeping pills
• Water pills

Using alcohol or drugs can also cause lethargy.

When symptoms of lethargy last for at least six months and healthcare providers can find no specific cause, that’s usually when the lethargy is classified as chronic fatigue syndrome. Chronic fatigue syndrome, or myalgic encephalomyelitis, is a disabling condition that causes extreme, prolonged exhaustion and that has no cure.

How to Treat Lethargy

No matter what’s causing your lethargy, feeling overly tired can disrupt your life. Fortunately, assuming your fatigue isn’t caused by a health condition that requires a professional course of treatment, there are some home remedies you can try to help reduce your fatigue. 

At-home options for reducing lethargy include:

• Ensuring you’re getting adequate sleep
• Eating a healthy, well-balanced diet
• Hydrating throughout the day
• Exercising regularly 
• Practicing yoga or meditation
• Removing stressors from your life
• Avoiding alcohol, smoking, and drugs

Depending on the cause of your lethargy, you can also consider taking a multivitamin or switching your medications. But make sure to consult a healthcare provider before making changes like these.

If your lethargy is caused by a health condition that can be managed or treated, a healthcare provider can discuss options for treating the root cause, as well as for managing the lethargy in the meantime. 

When to Seek Medical Help

If you’re unsure whether your lethargy is in response to a lifestyle change like stress or lack of sleep or a sign of an underlying health condition, consider talking with a healthcare provider. Fatigue is a common reason people visit their providers. In fact, an estimated 5–10% of all primary care visits are directly related to fatigue.

You should prioritize a visit to a healthcare provider if you are fatigued and experiencing any of the following:

• Confusion 
• Feeling dizzy
• Blurred vision
• Sudden weight gain or loss
• Depression and thoughts of harming yourself
• Constant headaches
• Insomnia
• Constipation
• Dry skin
• Intolerance to the cold

Based on your symptoms, health history, and lifestyle habits, your doctor may run blood, kidney function, liver function, and urine tests to determine the cause of the lethargy. 

Babies and Children With Lethargy

Lethargy is a common reason infants are brought to the emergency room. If your baby, or child, seems lethargic, call your provider. The provider can help determine whether the level of tiredness is nothing to worry about or a sign of a health problem like:

• Group B strep
• Chronic fatigue syndrome
• Dehydration
• Congenital heart defects

A Quick Review

Lethargy, or fatigue, is the state of feeling drowsy, unusually tired, or not alert. There are many causes of lethargy that range in severity. Some are obvious: you may feel fatigued after playing sports or if you haven’t slept well. Other causes may include illnesses or infections, such as diabetes, anemia, or cancer.

If home care remedies, including rest, don’t seem to help your lethargy—or if it’s paired with symptoms like headaches or depression—call a healthcare provider so you can determine what is causing the exhaustion and how to best manage it.