Lithium carbonate

• The dose of lithium prescribed varies from person to person, depending on your response to the medicine and your lithium blood level (see below). 
• Your doctor will start you on a low dose and increase it slowly as your body gets used to the medicine.
• The usual dose is 400 to 1200 mg daily, taken as a single dose or in 2 divided doses.
• Always take your lithium exactly as your doctor has told you.
• The pharmacy label on your medicine will tell you how much lithium to take, how often to take it and any special instructions.

• Read about what to do if you think a child or someone else has taken a medicine that's not for them.

• Timing: Take your lithium dose at the same times each day.
  • If you take lithium once daily, take your dose either in the morning or the evening
  • If you take lithium twice a day, take your dose in the morning and evening.
• Swallow lithium tablets and capsules with a full glass of water (200 to 250 mLs): Don't crush or chew the tablets and don't take them with hot liquids. It is best to take each dose with food to reduce nausea (feeling sick) and stomach upset.
• Missed dose: If you forget your dose, take it as soon as you remember that day. But if it's nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
• Keep taking lithium every day: It usually takes a few weeks to start working and it can take several months before you feel the full benefits. Don't stop taking lithium suddenly as your symptoms may return if you stop taking it too early. Talk to your doctor or nurse before stopping because if you do need to stop taking lithium it should be reduced slowly and they can advise you on how to do this.

Here are some things to know when you're taking lithium. Other things may be important as well, so ask your healthcare provider what you should know about.

• Alcohol: Alcohol may increase your chance of side effects such as drowsiness. Alcohol can also cause dehydration which in turn can affect your lithium levels. Limit drinking alcohol while on lithium.
• Food: You can eat normally while taking lithium. However, it’s best to avoid a low-sodium (low-salt) diet as this can increase the levels of lithium in your blood and increase the chance of getting side effects.
• Blood tests: You will need to have regular blood tests to make sure that your lithium dose is right and safe for you. Read more about this in the 'Monitoring and tests' section below.
• Other medicines: There are some medicines (including over-the-counter and complementary medicines, eg, vitamins, minerals, herbal, rongoā Māori and naturopathic medicines) that may interfere with how lithium works. This can affect the levels of lithium in your blood which can cause lithium toxicity. Always check with your pharmacist or doctor before you take any other medicines and before starting any new products.
• Recreational drugs: Using recreational drugs can affect the level of lithium in the body. For example, taking ecstasy while you’re on lithium can make you dehydrated, which can lead to lithium toxicity.
• Stay hydrated: You should drink plenty of water each day. Don't ignore feelings of thirst – keep up your fluid intake. Infections and illnesses like colds and flu or vomiting or diarrhoea can make you dehydrated and this can affect the level of lithium in your blood. Avoid drinking too many caffeine drinks such as tea and coffee as they can make you dehydrated.
• Pregnant or planning a pregnancy: Tell your doctor if you are pregnant, or are trying for a baby. If you take lithium when you are pregnant it can increase the risk of a baby having a birth defect. Your doctor will talk with you about your options, you may need to change treatment. Do not stop taking lithium without talking to your doctor. Read more about taking lithium during pregnancy.(external link)

Lithium levels

You'll need to have regular blood tests to make sure that your lithium dose is right and safe for you. This is because the amount of lithium in your bloodstream has to be just right – too little and it won't work well, too much and it could be harmful.

These blood tests are referred to as ‘a lithium level’, a ‘serum lithium level’ or a ‘plasma lithium level’. They are needed weekly in the early stages of your treatment and if your dose is changed, but are needed less often (3 monthly) once your lithium level is stable. 

Timing of the blood test to check your lithium level

It's important that blood samples to test lithium levels are taken at least 12 hours after you had your last dose of lithium. If blood is taken before this time, the lithium level won't have settled down in your blood since the last dose.

Signs that your lithium levels are too high

Having high levels of lithium in your blood can be harmful. This is best avoided by taking the right dose, keeping a steady fluid and salt intake and having regular blood tests. It is also helpful for you and your family to know the signs of high lithium levels (listed below) so that you can respond quickly and seek immediate medical attention.

A small number of people may not have any symptoms of toxicity when the level of lithium in their blood is too high.

Other tests

Lithium may cause changes in your weight, the way your thyroid gland works and your heart and kidney function. To keep an eye out for these effects, your doctor will monitor your health.

Before you start lithium, and while you are taking it, you will have your weight measured. You may be sent for tests to monitor your kidney and thyroid function and for an ECG test to assess your heart rate.

Like all medicines, lithium can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

As well as the serious side effects listed above, other side effects can happen when you are taking lithium.

Read more about medicines and side effects and reporting a reaction you think might be a side effect.