Stable on lithium for years — why is she shaky, sick and confused?
Ibuprofen slows the kidneys’ clearance of lithium. With so little room between helpful and toxic, the level tips over.
Select any card for the reasoning, what to watch for and an exam tip.
The puzzle
A woman has taken lithium for bipolar disorder for years, with steady levels. She buys ibuprofen for a bad back and takes it every day. A week later she has diarrhoea and a coarse tremor, and she is drowsy and confused.
The answer, step by step
Who is most at risk
- Older people, who need lower lithium doses.
- Kidney impairment, or dehydration from vomiting, diarrhoea or hot weather.
- Anyone starting an NSAID, ACE inhibitor, ARB or diuretic.
What to do
Key takeaway
NSAIDs raise lithium levels; so do ACE inhibitors, ARBs and diuretics. Steer people on lithium to paracetamol, check the level if an interacting drug is started, and know the signs of toxicity.