NSAIDs may increase
serum lithium levels leading to
toxicity, but there is great variability between different
NSAIDs and also between individuals taking the same
NSAID. For example, studies have found that
celecoxib causes a modest 17% increase in
lithium levels, yet case reports describe increases of up to about 350%. Similar effects occur with other NSAIDs, and it seems likely that all
NSAIDs will interact similarly. However, note that
sulindac seems unique in that it is the only
NSAID that has been reported to also cause a decrease in
lithium levels.
Factors such as advanced age, impaired
renal function, decreased sodium intake, volume depletion,
renal artery stenosis, and heart failure increase the risk of this interaction.
NSAIDs should preferably be avoided, especially if other risk factors are present, unless
serum lithium levels can be very well monitored (initially every few days) and the
lithium dosage reduced appropriately. Patients taking
lithium should be aware of the
symptoms of
lithium toxicity (see lithium) and told to report them immediately should they occur. This should be reinforced when they are given an
NSAID.