In the treatment of depression, primary care providers are often faulted for failing to give an antidepressant medication at a high enough dose. What is high enough? Answering this question turns out to be tricky.

Defining roughly equivalent doses of antidepressants is challenging enough. A Cochrane review team undertook a detailed analysis based on randomized trials.1 Their arduously computed value is shown in the middle column of the table, with clinically practical approximations on the right. (Available studies did not allow calculations for citalopram or duloxetine).

Many practitioners regard 20 mg of fluoxetine an inadequate dose for a full trial. They would routinely increase to 40 mg before allowing a conclusion of “been there, done that.” By extension, the dose equivalence table might suggest that doses in the right-hand column are minimums for fairtrials of each of these medications. But an examination of available data does not support this practice. Indeed, 5 mg of fluoxetine might be enough.