If you're on the right dose and the level of lithium in your blood is right, you may not have any side effects.
However, some people may still find lithium slows down their thinking or makes them feel a bit “numb.”
Common side effects
Common side effects of lithium are usually mild and go away by themselves. They're more likely to happen when you start taking lithium. There are things you can do to help cope with them:
Feeling sick (nausea) or being sick
Try to stick to simple meals and do not eat rich or spicy food. It might also help to take your medicine after eating.
If you’re being sick, take sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If you take contraceptive pills and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Diarrhoea
Drink plenty of fluids to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take contraceptive pills and have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
A dry mouth or a metallic taste in the mouth
Try sugar-free gum or sweets, or sipping cold drinks. If this does not help, talk to your pharmacist or doctor. Try not to have drinks with a lot of calories in as this might also mean you put on weight.
Slight shaking of the hands (mild tremor)
Talk to your doctor if this is bothering you or does not go away after a few days. These symptoms can be a sign that the dose is too high for you. Your doctor may change your dose or recommend taking your medicine at a different time of day.
Feeling tired or sleepy
As your body gets used to lithium, these side effects should wear off. If these symptoms do not get better within 2 weeks, your doctor may either reduce your dose or increase it more slowly. If that does not work, you may need to switch to a different medicine.
Keep taking the medicine but talk to your doctor or pharmacist if any of these side effects get worse or do not go away after a few days.
Serious side effects
The level of lithium in your blood will be checked regularly. Although it's rare, having too much lithium in your blood can cause side effects. This is because very high amounts of lithium can cause problems with your kidneys and other organs.
Immediate action required: Call 999 or go to A&E now if:
you have any of these symptoms:
- stomach ache, feeling sick (nausea) and having diarrhoea
- problems with your eyesight (blurred vision)
- feeling very thirsty, needing to pee more than normal, and lack of control over pee or poo
- feeling lightheaded or drowsy
- confusion and blackouts
- shaking, muscle weakness, muscle twitches, jerks or spasms affecting the face, tongue, eyes or neck
- difficulty speaking
These are signs of lithium toxicity, which is an emergency. Stop taking lithium straight away.
How to avoid high lithium levels in your blood
- Make sure that you go for the blood tests arranged by your doctor.
- 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’re doing intense exercise or in hot weather when you’ll sweat more.
- Drinking alcohol causes your body to lose water. It's best not to drink too much as it's likely to make you dehydrated, especially in hot weather when you’ll sweat more.
- Always tell any doctor or pharmacist that you’re taking lithium before you take any new medicines.
Serious allergic reaction
In rare cases, lithium may cause a serious allergic reaction (anaphylaxis).
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Long-term side effects
If you've been taking lithium for a long time, it can cause weight gain.
If you find you're putting on weight after taking lithium for a while, try to have a healthy balanced diet. Regular exercise will also help you keep your weight stable. Your doctor will usually monitor your weight while you're taking this medicine.
Taking lithium for a long time can also cause problems with your kidneys or thyroid gland.
Common signs of an underactive thyroid are tiredness, weight gain and feeling depressed. Signs of kidney problems include swollen hands or ankles, feeling tired and short of breath, changes in your pee and feeling sick.
Tell your doctor if you get any these symptoms. Your doctor will arrange blood tests to check for any changes in your thyroid and kidneys.
Other side effects
These are not all the side effects of lithium. For a full list, see the leaflet inside your medicine packet.
You can report any suspected side effect using the Yellow Card safety scheme.