Hi @*Beth*.

"When combined with lithium, NSAIDs can increase lithium levels in the blood resulting in an increased risk for serious adverse effects like confusion, tremor, slurred speech, and vomiting."
- From NAMI website.

I think Lithium working "quickly" might rather mean in 2 weeks, and not 2 days. The only meds I ever found worked in as little as 2 days were antipsychotics and benzos. And for me, sometimes antidepressants would already start a mood switch from depression to hypomania, mania or mixed states. In my youth, two weeks would seem like a lifetime. Now, it's like the flash of a lightning bolt.

From drugs.com:

"A reduction in manic symptoms should be noticed within 5 to 7 days [on Lithium] but the full therapeutic effect may require 10 to 21 days."