Lithium: uses, blood tests and toxicity warning signs

The NHS describes lithium as a mood stabiliser. It is used to treat mania and hypomania, to treat bipolar disorder, and for depression when other medicines have not worked. It may also reduce aggressive or self-harming behaviour. Lithium is a metal found naturally in rocks and food, and exactly how it works is not fully understood; it is believed to protect and help create neurons.

It can take several weeks or months to work. Most adults and children aged 12 and over can take it.

Lithium carbonate comes as standard and slow-release tablets, and lithium citrate comes as a liquid. The NHS lists Priadel, Camcolit and Liskonum tablets, and Priadel and Li-Liquid liquid. Different products release the medicine differently, so you should not move from one to another unless your doctor recommends it.

Swallow tablets whole with water or juice and do not chew them. A once-daily dose at night is common, partly so that a blood test can be timed about 12 hours after it.

Before treatment, you will have tests of kidney and thyroid function and your weight checked, and an ECG if you have a heart condition. During treatment, lithium levels are measured weekly at first and every 3 to 6 months once stable. Results go in a lithium record book, and you are given a lithium alert card for emergencies.

Common effects include nausea or vomiting, diarrhoea, dry mouth, a metallic taste, mild hand tremor and tiredness that should improve in about 2 weeks. A tremor that bothers you can mean the dose is too high, so tell your doctor.

Lithium toxicity is an emergency. Seek urgent care through 999 or A&E for stomach pain with nausea and diarrhoea, blurred vision, excessive thirst with frequent urination, light-headedness, confusion, blackouts, muscle shaking, weakness or spasms, or speech difficulty. The NHS says to stop taking lithium straight away in this situation.

Attend every blood test, keep your salt intake consistent, stay hydrated in hot weather or exercise, limit alcohol, and tell every health professional that you take lithium before they start a new medicine. Dehydration from vomiting, diarrhoea or ecstasy use can push levels up. Notify the DVLA if you have a bipolar diagnosis.

The NHS lists diuretics such as furosemide and bendroflumethiazide; anti-inflammatory painkillers including aspirin, ibuprofen, celecoxib and diclofenac; ACE inhibitors such as enalapril, lisinopril and ramipril; the antidepressants fluvoxamine, paroxetine and fluoxetine; antibiotics including trimethoprim, metronidazole and co-trimoxazole; and carbamazepine and phenytoin. There is not enough information to say herbal remedies are safe with lithium.

The NHS says lithium may be continued in pregnancy if necessary, with a small chance it affects the baby's heart development in the first 12 weeks, so a review before or when you learn you are pregnant is advised. Breastfeeding may be possible after specialist advice, and the baby may need blood tests.

Long-term, lithium can cause weight gain and affect the thyroid and kidneys, which is why monitoring continues. Never stop suddenly: reduce over weeks or months, unless toxicity is suspected. Report suspected side effects to the MHRA Yellow Card scheme.