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Lithium is a mood stabiliser medicine available only on prescription.

We do not know exactly how lithium works for mental health conditions, but we do know it's effective.

Lithium may take several weeks or months to work. As long as it controls your condition, you will usually take lithium for a long time.

Types of lithium

Lithium comes in:

  • slow release tablets such as Priadel
  • a liquid such as Priadel and Li-Liquid

It's important not to change types unless your doctor recommends it.

Priadel liquid and Li-Liquid are not authorised for use in Ireland so they are not commonly used. But your doctor may prescribe them as an 'exempt medicinal products' if they think they will benefit you.

Uses of lithium

Lithium is used to treat mental health conditions such as:

  • mania - feeling highly excited or distracted
  • hypo-mania - similar to mania, but less severe
  • bipolar disorder - where mood changes between very high and very low
  • regular periods of depression

Lithium can also reduce aggressive or self-harming behaviour.

Get emergency help

You might also need emergency help if you have a serious allergic reaction (anaphylaxis) or take too much.

If you take too much

The level of lithium in your blood should be checked regularly by your doctor.

Taking too much can cause an emergency known as lithium toxicity. You will need to go to the emergency department (ED).

Emergency action required: Call 112 or 999 or go to an ED if you have:

  • loss of appetite, feeling or being sick (vomiting)
  • problems with seeing such as blurred vision
  • needing to drink and pee more than normal
  • lack of control over pee or poo
  • feeling lightheaded or drowsy
  • confusion and blackouts
  • shaking, muscle weakness, jerks or spasms
  • difficulty speaking

Take your remaining medication and any leaflets with you.

Serious allergic reaction

A serious allergic reaction (anaphylaxis) from taking lithium is rare.

Emergency action required: Call 122 or 999 or go to an ED if:

  • you get a rash that's itchy, red, swollen or blistered
  • you're wheezing
  • you get tightness in your chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

When you start taking lithium

When you start on lithium you'll have a blood test every week to make sure you're taking the right dose.

Once your doctor is happy you'll have a blood test every 2 to 3 months.

Check if you can take lithium

Lithium can be taken by adults. It's not recommended for children and teenagers.

It may not be suitable if you:

  • have had an allergic reaction to lithium or other medicines
  • have heart disease
  • have severe kidney problems
  • have untreated hypothyroidism
  • have low levels of sodium
  • have Addison's disease
  • or someone in your family has a rare condition called Brugada syndrome
  • need to have surgery

Pregnancy and lithium

Do not take lithium if you are pregnant, especially in the first 3 months of your pregnancy unless considered essential by your doctor. Do not stop taking lithium before speaking to your doctor.

If you're trying to get pregnant, think you may be pregnant or become pregnant unexpectedly, talk to your doctor before taking lithium.

Try and talk to them well before you become pregnant, if possible. This is important.

Breastfeeding and lithium

Do not breastfeed if you are taking lithium.

Lithium passes easily to babies through breastmilk, causing high levels of lithium in their blood.

Contraception and fertility

Lithium does not affect contraception.

There is no clear evidence that lithium affects female fertility. There is small chance that it reduces sperm count in men.

Speak to your doctor if you're trying for a baby.

How and when to take lithium

You will usually take lithium once a day at night. This is because when you have your regular blood test, you need to have it 12 hours after taking your medicine.

Swallow tablets whole with a drink of water or juice. Do not chew them. You can take it with or without food.

If you're taking liquid, use the plastic syringe or spoon that comes with your medicine to measure the correct dose. Do not use a kitchen teaspoon as you will not get the right amount.

Do not stop taking lithium or change your dose, even if you start to feel better.

If you forget to take lithium

See the patient information leaflet that comes with your medicine for advice on what to do if you forget to take your medicine.

Non-urgent advice: Find your patient information leaflet

Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.

Priadel tablets

If you forget to take a dose, take it as soon as you remember, then go on as before.

Do not take a double dose to make up for a forgotten dose.

Side effects

If you're on the right dose you may not have any problems taking lithium.

However, some people find lithium slows down their thinking or makes them feel mentally numb.

Other side effects are usually mild and go away by themselves. They are more likely to happen when you start taking lithium.

Keep taking the medicine but talk to your doctor if side effects get worse or do not go away after a few days

Side effects include:

  • feeling sick (nausea)
  • diarrhoea
  • dry mouth, sometimes with a metallic taste in the mouth
  • needing to drink and pee more than usual
  • slight shaking of the hands
  • feeling tired or sleepy
  • gradual weight gain

This is not a full list of possible side effects.

See the patient information leaflet that comes with your medicine for a full list of side effects.

Non-urgent advice: Find your patient information leaflet

Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.

Report side effects

You can report any suspected side effects to the the Health Products Regulatory Authority (HPRA): report an issue -

Avoiding high lithium levels in your blood

Make sure that you go for the blood tests arranged by your doctor.

To keep levels steady it's important not to reduce your salt intake suddenly. Talk to your doctor if you want to reduce the amount of salt in your diet.

Drink plenty of fluids, especially if you are doing intense exercise or have an illness that causes you to sweat or have diarrhoea. Dehydration can cause your lithium levels to go up.

Urgent advice: Phone your doctor immediately if:

  • you have sickness and diarrhoea for more than a day or two

It's best not to drink alcohol too much as it's likely to make you dehydrated.

Taking lithium with other medications

Always remind your doctor or pharmacist that you are on lithium before you take new medicines

Always check with your pharmacist before buying any medicine or supplements over the counter (OTC). These may not be suitable with lithium.

Check with your doctor if you're already taking:

  • tablets that make you pee (diuretics) such as furosemide or bendroflumethiazide
  • non-steroidal anti-inflammatory drugs (NSAIDs) – used for pain relief and swelling such as aspirin, ibuprofen, celecoxib or diclofenac
  • heart or blood pressure medication such as enalapril, lisinopril or ramipril (ACE inhibitors)
  • medicines used for depression such as fluvoxamine, paroxetine or fluoxetine
  • antibiotics such as oxytetracycline, metronidazole, co-trimoxazole or trimethoprim
  • medicines for epilepsy such as carbamazepine or phenytoin

See your patient information leaflet for a full list of medicines which may interfere with lithium.

Non-urgent advice: Find your patient information leaflet

Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.

Herbal remedies or supplements

It's not known if herbal supplements are safe to take with lithium.

They're not tested in the same way as pharmacy and prescription medicines.

Recreational drugs

Using recreational drugs can affect the level of lithium in the body.

Taking ecstasy while you're on lithium can make you dehydrated.

Tell your doctor if you may take recreational drugs while you're on lithium.


Lithium can make you drowsy so it's best to stop drinking alcohol during the first few days of taking lithium.

If you feel OK after this, you can drink alcohol but it's best not to drink too much as it's likely to make you dehydrated. This can increase the chance of high levels of lithium in your blood.

Fact check

This content was fact checked by a pharmacist, a GP, the National Medication Safety Programme (Safermeds) and the Health Products Regulatory Authority (HPRA).

Page last reviewed: 24 September 2021
Next review due: 24 September 2024

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.