Lithium can help stabilize a person’s mood. However, it may also cause side effects, such as diarrhea, tremors, and weight gain. Long-term use may affect kidney or thyroid function.

Lithium is a medication used for the treatment of bipolar disorder. It is available in the United States under the brand name Lithobid.

Lithium can be life changing for people who may find bipolar disorder difficult to manage, but its use does come with side effects. The medication has a narrow therapeutic index, meaning there is a small range between therapeutic and toxic levels. So healthcare professionals recommend consistent use and close monitoring.

This article identifies some of the more common short-term and long-term side effects of taking lithium.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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According to older research in a 2016 article, 67–90% of people taking lithium experience at least one side effect of the drug.

Some side effects that occur after first taking lithium tend to go away with time. One example is nausea. As per the 2016 article, nausea may affect about 10–20% of people in the early stages of lithium treatment.

Other short-term side effects that a person may experience when first taking lithium include:

Another potential side effect is cognitive dulling, which is when a person does not feel as “sharp” or alert as they once did. Sometimes, a doctor may have difficulty telling whether a person is experiencing depression or cognitive dulling due to lithium treatment.

High lithium levels

People who take lithium may require regular blood tests as lithium can build up in the blood and become toxic at high levels. According to the package insert for lithium, levels higher than 1.5 milliequivalents per liter (mEq/L) of blood serum can cause health problems.

The package insert also shows that a desirable and safe range for most people is between 0.6–1.2 mEq/L.

Early side effects of high lithium levels include:

A person whose lithium levels are higher than 2.0 mEq/L may experience additional side effects, such as:

Experts consider lithium levels above 3.0 mEq/L to be very high. These levels can cause organ failure and even death.

The associated symptoms above can provide an idea of what to expect. However, it is important to know that side effects can happen at different blood concentrations. That is, for example, some people may experience tinnitus at levels below 2.0 mEq/L.

Currently, there is no medication to treat a lithium overdose. Treatment generally involves monitoring the person, correcting their electrolyte levels, and performing dialysis to filter their blood.

Severe side effects of long-term lithium use are hypothyroidism and kidney problems.

According to an older 2015 review article, these side effects are most likely to affect females below the age of 60 years. They are also more common among people with higher-than-average concentrations of lithium in the blood.

Kidney dysfunction

According to the package insert for lithium, long-term use of this drug can affect the kidneys’ ability to concentrate urine. This problem can cause a condition called nephrogenic diabetes insipidus (NDI). Symptoms include extreme thirst and frequent urination.

NDI can cause dehydration and a rise in blood lithium levels. These side effects could harm both the kidneys and the rest of the body.

People who take lithium might require regular monitoring of their sodium levels and kidney function. If these tests show even slight issues with the kidneys, a doctor may prescribe a lower dosage of lithium. Alternatively, they may recommend a different medication altogether.

Thyroid problems

Hypothyroidism is another concern for people taking lithium. In a person with hypothyroidism, the thyroid gland does not produce enough hormones.

This condition can cause symptoms, including:

If a person is taking lithium, a doctor may recommend regular tests to monitor thyroid function.

Hyperparathyroidism

Lithium can not only cause long-term thyroid problems but also affect the parathyroid glands. These glands are mainly responsible for regulating calcium levels in the body.

Hyperparathyroidism can affect the body’s ability to detect calcium, leading to a condition called hypercalcemia. Hypercalcemia occurs when a person’s calcium levels are too high.

Hypercalcemia can lead to further complications, such as osteoporosis and cardiovascular issues.

According to an older 2015 article, lithium-induced hyperparathyroidism is four times more likely to occur in females than in males.

If a person is taking lithium and planning on becoming pregnant, it is advisable to speak with a doctor. Taking lithium raises the risk of a birth defect called Ebstein’s anomaly. This particular birth irregularity affects the tricuspid valve in the heart.

Doctors will not usually suggest stopping lithium treatment during pregnancy. Instead, they tend to monitor a person’s lithium levels very closely.

They will also recommend an ultrasound of the baby’s heart between 16 weeks and 20 weeks into the pregnancy.

As lithium can pass into a person’s breast milk, doctors do not usually recommend breastfeeding while taking this medication. People can talk with their doctor or midwife for advice on alternative feeding options.

For lithium to work effectively, it is important to take it consistently every day. Missing a dose can affect how well the medication works.

It is advisable to seek emergency medical attention if a person experiences any of the following symptoms of high lithium levels:

  • confusion
  • difficulty walking
  • extreme increase in thirst
  • severe hand tremors
  • severe nausea and vomiting
  • vision changes

It’s important for a person to take lithium at regular intervals for the medication to work effectively. However, people may commonly avoid taking lithium as per their doctor’s recommendations due to side effects.

High lithium levels can result in a range of unpleasant symptoms. They can also result in severe health complications and even death.

If a person experiences worrying symptoms while taking lithium, it’s important to speak with a doctor. They can often recommend ways to lower the side effects of lithium treatment without stopping it.