Lithium Toxicity: Types, Symptoms, Diagnosis, and Treatment

Lithium toxicity is a serious condition that occurs when you have too much lithium in your system. Lithium is primarily prescribed as a mood stabilizer, so most cases of lithium toxicity occur in people with bipolar disorder who take the medication.

Types of Toxicity

There are three types of lithium toxicity: acute, chronic, and acute-on-chronic.

Acute Toxicity

Acute lithium toxicity occurs when someone not taking lithium ingests it. This might happen if someone takes pills from the wrong bottle, a child gets into a parent's medication, or someone takes lithium in a suicide attempt.

Acute toxicity carries less medical risk and less severe symptoms than the other types, depending on the amount taken. That is because lithium clears from the body more quickly when the body is not used to it.

Chronic Toxicity

Chronic lithium toxicity occurs when someone taking lithium daily has a serum blood level that has crept into the toxic range. Possible causes for this level increase include a dosage increase, dehydration, interactions with other medications, and problems with kidney function.

Chronic toxicity is less likely to be detected early than the other types, so more severe symptoms may appear before it is identified. Medications that can contribute to dehydration or cause the kidneys not to function as well as normal include diuretics, angiotensin-converting enzyme (ACE) inhibitors, and nonsteroidal anti-inflammatory drugs (NSAIDs).

Acute-on-Chronic Toxicity

Acute-on-chronic toxicity occurs when someone regularly taking lithium accidentally or intentionally takes a higher dose than prescribed.

Because the levels of lithium in the blood that make the medication effective and the levels that make it toxic are close together, the additional amount that causes acute-on-chronic toxicity does not have to be very high.

Acute-on-chronic toxicity is the most severe form of lithium toxicity and can have long-term consequences.

Testing

Lithium is a soft metal that can be helpful in the right doses and harmful in large doses. Doctors order periodic blood tests for people taking lithium because the difference between an effective and toxic dose is small.

A safe, effective dose for one person may be toxic to another. The higher the serum level, the stronger the side effects and the more likely the appearance of toxic symptoms.

A therapeutic lithium level is between 0.6 to 1.2 milliequivalents per liter (mEq/L). Symptoms of toxicity begin to show up when the level gets to 1.5 mEq/L or more.

The levels of toxicity are classified as:

• Mild: 1.5 to 2.5 mEq/L
• Moderate: 2.5 to 3.5 mEq/L
• Severe: above 3.5 mEq/L

Symptoms

Symptoms of lithium toxicity vary depending on the type of toxicity.

Acute Toxicity

Common symptoms of acute toxicity include:

• Diarrhea
• Dizziness
• Nausea
• Stomach pains
• Vomiting
• Weakness

Nervous system symptoms that may develop later include:

• Hand tremors
• Drowsiness
• Confusion or agitation
• Inability to fully control the arms and legs (ataxia)
• Muscle twitches
• Slurred speech
• Eye movements that you cannot control (nystagmus)

Severe cases can cause symptoms such as:

• Seizures
• Coma
• Brain injury
• In rare cases, heart problems

Chronic Toxicity

Unlike in acute lithium poisoning, people with chronic lithium toxicity are less likely to have stomach and intestinal problems and instead usually present with neurological symptoms first, such as:

• Slurred speech
• Drowsiness
• Ataxia
• Confusion or agitation
• Tremors
• Increased reflexes

Severe cases of chronic toxicity may cause symptoms such as:

• Memory problems and other cognitive impairment
• Significant movement problems
• Psychosis
• Kidney failure
• Seizures
• Coma

In a small number of people, severe symptoms may persist long-term even with successful treatment.

Acute-On-Chronic Toxicity

Symptoms of this condition typically include both the common gastrointestinal symptoms of acute toxicity and some severe symptoms of chronic toxicity.

When to Get Help

If you or a loved one shows any signs of lithium toxicity, especially severe symptoms, you should go to the emergency room or call 911. At the very least, call the poison control helpline at 1-800-222-1222 to get advice on what to do.

If you can, take the lithium bottle along with you so the medical staff can see the name, dose, and strength. Try to find out when the lithium was taken and how much was taken, too.

If you are having suicidal thoughts, contact the National Suicide Prevention Lifeline at 1-800-273-8255 for support and assistance from a trained counselor. If you or a loved one are in immediate danger, call 911.

Diagnosis

A doctor will diagnose lithium toxicity based on the signs and symptoms, the results of a physical exam, the patient's history of taking lithium, and a blood test to determine the lithium level in the blood. The amount of lithium in the blood may not reflect the severity of the toxicity if the poisoning is acute or acute-on-chronic. In such cases, doctors will rely more on the symptoms.

Treatment

Treatment for lithium toxicity depends on the severity and type of toxicity. In all cases, intravenous (IV) fluids will be given to ensure the patient is not dehydrated and help move the lithium out of the system.

Acute Toxicity

Depending on the amount taken and how soon after ingestion is discovered, treatment may include:

• Activated charcoal, if the patient also took other substances
• Kidney dialysis, in severe cases
• Whole bowel irrigation, in which a polyethylene glycol solution is used to flush large amounts or extended-release lithium from the system

Whole bowel irrigation is only done if the patient is not experiencing lethargy or confusion.

Chronic Toxicity

Lithium will clear the body more slowly in chronic toxicity.

• For mild toxicity, treatment may include reducing the lithium dose or stopping lithium altogether.
• For moderate or severe toxicity, treatment may include IV fluids, dialysis, and medications to treat the symptoms.

Acute-On-Chronic Toxicity

Treatment for acute-on-chronic toxicity typically includes IV fluids, dialysis, and medications to treat the symptoms.