Lithium: What Care Staff Need to Know About Monitoring and Toxicity

Lithium is one of the most effective medicines for preventing relapse in bipolar disorder, but it has a narrow safe range. Too little may not work, and too much can be dangerous. Care staff often see people day to day, which makes them well placed to notice early signs of toxicity, dehydration or missed monitoring. This guide sets out what staff should know and when to act.

It is general information based on NHS good practice standards for using lithium safely, not clinical advice. Follow the prescriber's instructions, the person's care plan and local policy. If you suspect lithium toxicity, treat it as urgent and seek medical help.

Why lithium is closely monitored

Lithium is cleared by the kidneys. If someone becomes dehydrated, develops kidney problems or starts a medicine that affects the kidneys, lithium can build up in the blood. The condition it is used for is covered in our bipolar disorder guide, but the safety points here apply whichever diagnosis it was prescribed for.

Blood tests and routine checks

NHS Scotland's good practice standards set out the following pattern:

• lithium levels should be taken as a 12-hour trough, about 12 hours after the last dose
• after starting lithium or changing the dose, the first level should be no earlier than five to seven days later
• in maintenance, levels are usually checked about every three months
• thyroid function and kidney function, including calcium, are usually checked about every six months
• checks are done more often if the person's health changes or they start interacting medicines

For new patients, the target range in the same standards is 0.6 to 0.8 mmol/L, and a higher range of 0.8 to 1.0 mmol/L may be used for people with a history of relapse. Targets are set by the prescriber, so never adjust a dose based on a number alone. Local protocols may vary slightly, so follow the one that applies to you.

Timing matters. A blood sample taken at the wrong time can give a misleading result, so make sure the person takes their evening dose at the usual time and has the test about 12 hours later.

Signs of lithium toxicity

The standards list these signs:

• coarse tremor and muscle twitches
• stomach upset and diarrhoea
• weakness
• unsteady walking and falls
• slurred speech and blurred vision
• drowsiness and confusion

These can be mistaken for the effects of age, a stroke, an infection or other medicines. Where someone on lithium shows any of them, seek urgent medical advice and do not assume they are a normal part of ageing. Link this to your falls risk assessment, as covered in our falls prevention guide.

Medicines and interactions

The standards advise avoiding some medicines where possible because they can raise lithium levels. These include non-steroidal anti-inflammatory drugs such as ibuprofen, naproxen and celecoxib, ACE inhibitors such as ramipril, angiotensin 2 antagonists such as losartan, and diuretics, especially thiazides. Staff should:

• make sure anyone who prescribes or supplies medicines knows the person takes lithium
• check carefully before giving over-the-counter painkillers, which are a common problem
• tell the prescriber about any new medicine, including those started by hospitals or out-of-hours services
• record the person as taking lithium on every medication record

Fluids, salt and illness

Dehydration is a major risk. Vomiting, diarrhoea and heavy sweating can all cause levels to climb. The standards advise people to keep up their fluids and to keep a steady amount of salt in their diet, and to seek medical advice if diarrhoea or vomiting lasts more than 24 hours. In hot weather or illness, staff should offer drinks regularly, record fluid intake where there is concern, and contact the prescriber or GP early.

Supporting the person

• Keep a diary of blood tests, and arrange them in advance.
• Explain to the person, in a way they can understand, why the checks matter.
• Watch for changes in mood, sleep or behaviour. Lithium helps to prevent relapse, so a sudden change should be reported.
• Do not stop lithium suddenly without medical advice.
• Where the person is at risk of self-harm, tell the team that lithium can be dangerous in overdose, and follow the person's safety plan. See our suicide and self-harm awareness training.

Frequently asked questions

Can someone on lithium take ibuprofen?

NSAIDs such as ibuprofen can raise lithium levels, so they should be avoided where possible. Ask the prescriber or pharmacist before giving any.

What should I do if I suspect toxicity?

Treat it as urgent. Contact the GP, out-of-hours service or emergency services as appropriate, and tell them the person takes lithium.

How often are levels checked?

Usually about every three months once stable, but more often after dose changes or illness, and according to local protocol.

Where can teams find training?

See the CPD hub for professional development options for care and healthcare teams.

Learnsignal will update this guide as national guidance changes.