It is known that (through different mechanisms) the following classes of medications can affect male fertility: antihypertensive drugs, alpha blockers, antidepressants, cimetidine and some antibiotics (especially erthromycin, tetracycline). A researcher has reported that current FDA drug analysis evaluate male fertility concerns poorly, if at all. Because of this, he advised that caution should be exercised prescribing these medications for long time periods, in men who are concerned about fathering children.
Source: Renal and Urology News, Dec. 2009