Hospitalized 4 dehydration. bld work showed low platelet count of 128. bld work 3 mnths ago ok. switched to 40mg prozac (fluoxetine) from 40mg zlft on 6/10. cause?

Probably ok: I assume the 128 is 128 thousand? If you're otherwise healthy and have no signs or symptoms of illness, results slightly outside the normal range on a complete blood count may not be a cause for concern, and follow-up may not be needed. At my institution a platelet count of 125,000 is normal. Platelet counts go up and down all the time, especially with acute illness, like your dehydration.

Not the meds: Neither Zoloft (sertraline) or Prozac cause low platelet counts. In fact, a platelet count of 128 is not especially low and is not low enough to be concerned about an illness. The most common cause of a slightly low platelet count is an inaccurate count due to clumping of those cells, especially if you were dehydrated at the time. A simple repeat will be reassuring.