Which over-the-counter medication should a client discontinue while taking lithium?

Ibuprofen should be discontinued while taking lithium because it can increase lithium levels in the body, potentially leading to lithium toxicity. Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can affect kidney function and fluid balance, which is critical because lithium is primarily eliminated through the kidneys. When kidney function is compromised or fluid retention occurs, lithium can accumulate, resulting in elevated serum levels that may lead to adverse effects such as nausea, tremors, confusion, and in severe cases, renal failure.

In contrast, aspirin is generally safer for individuals on lithium, as it does not significantly affect lithium levels. Famotidine, an H2 antagonist used to reduce stomach acid, does not interact significantly with lithium, nor does bisacodyl, a laxative, pose risks related to lithium metabolism or elimination. Understanding these interactions helps ensure safer medication management for clients on lithium therapy.