Unwanted effects

• Relatively harmless: nausea, mild diarrhoea, fine tremor (which can be treated by a beta-blocker), weight gain, oedema, and exacerbation of psoriasis.

• Acute symptoms suggesting lithium intoxication: vomiting, diarrhoea, coarse tremor, drowsiness, vertigo, dysarthria, and cardiac arrhythmia. This condition is serious and, if such symptoms develop, lithium should be stopped immediately and blood taken for estimation of the serum level.

• Long-term effects of gradual onset: hypothyroidism (affecting 3 per cent of patients per year; it is usually reversible when the drug is stopped, and treatable with thyroxine if lithium is continued); rarely, thyrotoxicosis; and histological and functional changes in the kidney, of uncertain significance.

Case example

A postgraduate student, 23 years old, presented with an episode of psychotic depression which responded well to inpatient treatment, but he developed a manic illness some months later. He was started on lithium, but stopped taking it after a few days, complaining of tremor; he had also, through a doctor relative, found out about its unwanted effects, and felt that these had not been properly discussed with him. He declined other mood stabilizers, as he had become distrustful.

He recovered, but had a further severe manic episode 1 year later. This time, he responded only slowly to antipsychotic medication, and valproate was added with gradual success.

He then took valproate for several years; he continued to have affective episodes approximately annually, although they were less severe and could be managed without inpatient admission. He came to accept the medication as the price of his mental stability.

Lithium should be used only in low dose, and under frequent supervision, in patients with cardiac or renal impairment, thyroid disease, diabetes insipidus, Addison's disease, or obesity, or on diuretic therapy. Neurological impairment after combined dosage with lithium and haloperidol in high dose has been reported. Use in early pregnancy is teratogenic, the most common foetal malformation affecting the tricuspid valve of the heart. This and other deformities can be detected by ultrasound. After the first trimester, lithium is believed to be safe, and may need to be continued in women with severe manic-depressive illness, although the drug should be stopped for a few days at the time of delivery because of the risk of toxicity. Lithium enters breast milk.

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