9 Lithium Side Effects You Should Know About

Lithium (Lithobid) is an FDA-approved medication for bipolar disorder. It’s a mood stabilizer, which helps balance out manic and depressive episodes.

Lithium can be an effective treatment, but it doesn’t come without side effects. Lithium is a narrow therapeutic index drug. This means that small dose changes can make a huge difference in how the medication works. Lithium levels are closely monitored to help maximize the medication’s benefits while reducing its risks.

But even with proper monitoring, side effects are still possible. Below, we’ll discuss nine potential lithium side effects and how you might manage them.

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1. Shaky hands

Shaky hands (tremors) is a common lithium side effect. It’s typically experienced when first starting the medication, but it can happen at any time. Tremors may be more obvious when trying to do activities like holding pens or cups. Excessive caffeine intake, personal or family history of tremors, and anxiety can raise your risk of experiencing this side effect.

In most cases, tremors aren’t harmful. But they can also be a symptom of lithium toxicity, a serious side effect discussed in more detail below. If you suddenly notice tremors after you’ve been taking lithium for a while, or they’ve recently gotten worse, let your healthcare provider know.

2. Frequent urination

Some studies show that up to 70% of people who take lithium experience frequent urination. Lithium causes the kidneys to release more water, thus making more urine. Long-term lithium treatment and higher lithium levels can make this side effect more likely.

Over time, increased urination can lead to dehydration. The amount of water in the body affects blood lithium levels. Too little water (dehydration) can lead to high, or even toxic lithium levels So it’s important to drink plenty of water while taking lithium.

Diarrhea, vomiting, and excessive exercise or sweating can also dehydrate you. Let your healthcare provider know if you experience any of these events. Or if you have a dry mouth, dark urine, or too little urine. These are symptoms of dehydration.

3. Excess thirst

Since lithium can increase urination, it might cause you to feel more thirsty. About the same amount (70%) of people taking lithium reported excessive thirst along with their symptoms of excess urine. As mentioned above, drinking plenty of water while taking lithium is important.

If your mouth feels dry despite staying hydrated, try chewing sugar-free gum or sucking on hard candy. You can also try saliva substitutes like Biotene.

4. Nausea

Many medications cause nausea when first starting, and lithium is no exception. Up to 20% of people taking lithium may experience nausea. But it’s more likely to happen when first starting it.

It may help to take your lithium dose with food. Vomiting is uncommon, but still possible. However, if vomiting occurs with other symptoms — like tremors, slurred speech, or confusion — seek medical treatment. These are potential symptoms of lithium toxicity.

5. Thyroid problems

Lithium can cause thyroid problems. These can include both an underactive thyroid (hypothyroidism) or an overactive thyroid (hyperthyroidism). Hypothyroidism is more common. Some studies have found that more than half of those taking lithium experience some degree of hypothyroidism.

Common symptoms of hypothyroidism include fatigue, weight gain, and feeling cold when others don’t. But some people may not have any symptoms. For this reason, your healthcare provider will periodically check your thyroid hormone levels while taking lithium. If hypothyroidism does occur, it can typically be managed with thyroid medications, like levothyroxine (Synthroid).

6. Lithium toxicity

Lithium toxicity is a serious side effect that can happen when lithium levels in the blood get too high. In severe cases, lithium toxicity can be fatal. Your healthcare provider will order blood tests periodically to make sure your lithium dose is safe. But you should always let your provider know if you’re experiencing symptoms of lithium toxicity.

Mild symptoms include:

• Tremors

• Nausea

• Diarrhea

• Blurry vision

• Dizziness

• Confusion

• Impaired coordination, balance, speech

More severe symptoms of lithium toxicity include:

• Shortness of breath

• Seizures

• Coma

• Kidney failure

• Abnormal heart rhythms

We mentioned above that dehydration can lead to lithium toxicity. But other things can also cause it, such as kidney problems and a low-sodium diet. Lithium also has many potential interactions that raise the risk of lithium toxicity.

If you believe you or a loved one may have taken too much lithium, contact Poison Control at 1-800-222-1222. If you or a loved one are experiencing symptoms of lithium toxicity, seek immediate medical care or call 911.

7. Low sodium levels

Because of how the kidneys process lithium, this medication can also cause low sodium levels. Sodium is an electrolyte that helps regulate many bodily functions, including blood pressure and fluid balance. Low sodium levels can cause symptoms such as headache, tiredness, or nausea. Severely low levels can cause confusion, seizures, or even trouble breathing.

When taking lithium, it’s important to keep your salt intake consistent. If you plan to change the amount of salt in your diet, discuss this with your healthcare provider first. In some cases, lithium dose changes may be needed.

8. Kidney damage

Over time, lithium can impact how well the kidneys work to filter out waste and excess fluid. In some cases, this can lead to chronic kidney disease (CKD). For this reason, blood tests are done before starting lithium and from time to time to keep track of your kidneys’ function while taking lithium. The risk of CKD increases with age, the amount of time you’ve taken lithium, and the number of past lithium toxicity episodes.

Your healthcare provider may detail some ways to lower the risk of kidney damage from lithium, including:

• Taking the lowest dose of lithium needed to treat your symptoms

• Going for all recommended lithium blood tests on time

• Going for all recommended kidney function tests on time

• Taking an extended-release version lithium once a day

9. Serotonin syndrome

While not fully understood, experts believe part of how lithium works is by raising serotonin levels in the brain. But too much serotonin can lead to serotonin syndrome. Serotonin syndrome is a rare but potentially life-threatening lithium side effect. Serotonin syndrome is more likely to happen when taking lithium with other medications that increase serotonin levels, including antidepressants, certain opioids, and St. John’s wort.

Some symptoms of serotonin syndrome can include:

• Sweating

• Tremors

• Fast heart rate

• High fever

• Uncontrollable movements of the arms or legs

Contact your healthcare provider if you believe you’re experiencing serotonin syndrome. Severe cases require treatment in a hospital setting.

When should I contact my healthcare provider about lithium side effects?

Many of lithium’s side effects, like shaky hands, nausea, and increased thirst or urination, may cause feelings of general discomfort. The symptoms are typically mild and tend to improve over time as your body adjusts to the medication. If any of these side effects are excessive or make it hard to do your day-to-day activities, talk with your healthcare provider. But don’t stop taking lithium without talking to them first.

If severe side effects happen, like lithium toxicity or serotonin syndrome, immediately seek medical attention. Sharing a medication list with your healthcare provider and pharmacist can help you avoid interactions that raise the risk of these complications.

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Written by:

Victoria Dadebo, PharmD, BCPS

Victoria Dadebo is a freelance pharmacy writer who began contributing to GoodRx in 2022. She has experience in both community and hospital settings, and she is furthering her pharmacy training to specialize in mental health.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Tegan Smedley, PharmD, APh

Tegan Smedley, PharmD, APh, has 10 years of experience as a pharmacist. She has worked in a variety of settings, including retail, hospital, and ambulatory care.

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